1. 20 3月, 2014 31 次提交
    • S
      arm64, debug-monitors: Fix CPU hotplug callback registration · 4b0b68af
      Srivatsa S. Bhat 提交于
      Subsystems that want to register CPU hotplug callbacks, as well as perform
      initialization for the CPUs that are already online, often do it as shown
      below:
      
      	get_online_cpus();
      
      	for_each_online_cpu(cpu)
      		init_cpu(cpu);
      
      	register_cpu_notifier(&foobar_cpu_notifier);
      
      	put_online_cpus();
      
      This is wrong, since it is prone to ABBA deadlocks involving the
      cpu_add_remove_lock and the cpu_hotplug.lock (when running concurrently
      with CPU hotplug operations).
      
      Instead, the correct and race-free way of performing the callback
      registration is:
      
      	cpu_notifier_register_begin();
      
      	for_each_online_cpu(cpu)
      		init_cpu(cpu);
      
      	/* Note the use of the double underscored version of the API */
      	__register_cpu_notifier(&foobar_cpu_notifier);
      
      	cpu_notifier_register_done();
      
      Fix the debug-monitors code in arm64 by using this latter form of callback
      registration.
      
      Cc: Catalin Marinas <catalin.marinas@arm.com>
      Cc: Russell King <rmk+kernel@arm.linux.org.uk>
      Cc: Ingo Molnar <mingo@kernel.org>
      Acked-by: NWill Deacon <will.deacon@arm.com>
      Signed-off-by: NSrivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
      Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
      4b0b68af
    • S
      arm64, hw_breakpoint.c: Fix CPU hotplug callback registration · 3d0dc643
      Srivatsa S. Bhat 提交于
      Subsystems that want to register CPU hotplug callbacks, as well as perform
      initialization for the CPUs that are already online, often do it as shown
      below:
      
      	get_online_cpus();
      
      	for_each_online_cpu(cpu)
      		init_cpu(cpu);
      
      	register_cpu_notifier(&foobar_cpu_notifier);
      
      	put_online_cpus();
      
      This is wrong, since it is prone to ABBA deadlocks involving the
      cpu_add_remove_lock and the cpu_hotplug.lock (when running concurrently
      with CPU hotplug operations).
      
      Instead, the correct and race-free way of performing the callback
      registration is:
      
      	cpu_notifier_register_begin();
      
      	for_each_online_cpu(cpu)
      		init_cpu(cpu);
      
      	/* Note the use of the double underscored version of the API */
      	__register_cpu_notifier(&foobar_cpu_notifier);
      
      	cpu_notifier_register_done();
      
      Fix the hw-breakpoint code in arm64 by using this latter form of callback
      registration.
      
      Cc: Catalin Marinas <catalin.marinas@arm.com>
      Cc: Lorenzo Pieralisi <Lorenzo.Pieralisi@arm.com>
      Cc: Ingo Molnar <mingo@kernel.org>
      Acked-by: NWill Deacon <will.deacon@arm.com>
      Signed-off-by: NSrivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
      Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
      3d0dc643
    • S
      x86, kvm: Fix CPU hotplug callback registration · 460dd42e
      Srivatsa S. Bhat 提交于
      Subsystems that want to register CPU hotplug callbacks, as well as perform
      initialization for the CPUs that are already online, often do it as shown
      below:
      
      	get_online_cpus();
      
      	for_each_online_cpu(cpu)
      		init_cpu(cpu);
      
      	register_cpu_notifier(&foobar_cpu_notifier);
      
      	put_online_cpus();
      
      This is wrong, since it is prone to ABBA deadlocks involving the
      cpu_add_remove_lock and the cpu_hotplug.lock (when running concurrently
      with CPU hotplug operations).
      
      Instead, the correct and race-free way of performing the callback
      registration is:
      
      	cpu_notifier_register_begin();
      
      	for_each_online_cpu(cpu)
      		init_cpu(cpu);
      
      	/* Note the use of the double underscored version of the API */
      	__register_cpu_notifier(&foobar_cpu_notifier);
      
      	cpu_notifier_register_done();
      
      Fix the kvm code in x86 by using this latter form of callback registration.
      
      Cc: Gleb Natapov <gleb@kernel.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: Ingo Molnar <mingo@kernel.org>
      Cc: "H. Peter Anvin" <hpa@zytor.com>
      Acked-by: NPaolo Bonzini <pbonzini@redhat.com>
      Signed-off-by: NSrivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
      Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
      460dd42e
    • S
      x86, oprofile, nmi: Fix CPU hotplug callback registration · 76902e3d
      Srivatsa S. Bhat 提交于
      Subsystems that want to register CPU hotplug callbacks, as well as perform
      initialization for the CPUs that are already online, often do it as shown
      below:
      
      	get_online_cpus();
      
      	for_each_online_cpu(cpu)
      		init_cpu(cpu);
      
      	register_cpu_notifier(&foobar_cpu_notifier);
      
      	put_online_cpus();
      
      This is wrong, since it is prone to ABBA deadlocks involving the
      cpu_add_remove_lock and the cpu_hotplug.lock (when running concurrently
      with CPU hotplug operations).
      
      Instead, the correct and race-free way of performing the callback
      registration is:
      
      	cpu_notifier_register_begin();
      
      	for_each_online_cpu(cpu)
      		init_cpu(cpu);
      
      	/* Note the use of the double underscored version of the API */
      	__register_cpu_notifier(&foobar_cpu_notifier);
      
      	cpu_notifier_register_done();
      
      Fix the oprofile code in x86 by using this latter form of callback
      registration. But retain the calls to get/put_online_cpus(), since they are
      used in other places as well, to protect the variables 'nmi_enabled' and
      'ctr_running'. Strictly speaking, this is not necessary since
      cpu_notifier_register_begin/done() provide a stronger synchronization
      with CPU hotplug than get/put_online_cpus(). However, let's retain the
      calls to get/put_online_cpus() to be consistent with the other call-sites.
      
      By nesting get/put_online_cpus() *inside* cpu_notifier_register_begin/done(),
      we avoid the ABBA deadlock possibility mentioned above.
      
      Cc: Robert Richter <rric@kernel.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: Ingo Molnar <mingo@kernel.org>
      Cc: "H. Peter Anvin" <hpa@zytor.com>
      Signed-off-by: NSrivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
      Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
      76902e3d
    • S
      x86, pci, amd-bus: Fix CPU hotplug callback registration · 9f668f66
      Srivatsa S. Bhat 提交于
      Subsystems that want to register CPU hotplug callbacks, as well as perform
      initialization for the CPUs that are already online, often do it as shown
      below:
      
      	get_online_cpus();
      
      	for_each_online_cpu(cpu)
      		init_cpu(cpu);
      
      	register_cpu_notifier(&foobar_cpu_notifier);
      
      	put_online_cpus();
      
      This is wrong, since it is prone to ABBA deadlocks involving the
      cpu_add_remove_lock and the cpu_hotplug.lock (when running concurrently
      with CPU hotplug operations).
      
      Instead, the correct and race-free way of performing the callback
      registration is:
      
      	cpu_notifier_register_begin();
      
      	for_each_online_cpu(cpu)
      		init_cpu(cpu);
      
      	/* Note the use of the double underscored version of the API */
      	__register_cpu_notifier(&foobar_cpu_notifier);
      
      	cpu_notifier_register_done();
      
      Fix the amd-bus code in x86 by using this latter form of callback
      registration.
      
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: Ingo Molnar <mingo@kernel.org>
      Cc: "H. Peter Anvin" <hpa@zytor.com>
      Acked-by: NBjorn Helgaas <bhelgaas@google.com>
      Signed-off-by: NSrivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
      Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
      9f668f66
    • S
      x86, hpet: Fix CPU hotplug callback registration · 9014ad2a
      Srivatsa S. Bhat 提交于
      Subsystems that want to register CPU hotplug callbacks, as well as perform
      initialization for the CPUs that are already online, often do it as shown
      below:
      
      	get_online_cpus();
      
      	for_each_online_cpu(cpu)
      		init_cpu(cpu);
      
      	register_cpu_notifier(&foobar_cpu_notifier);
      
      	put_online_cpus();
      
      This is wrong, since it is prone to ABBA deadlocks involving the
      cpu_add_remove_lock and the cpu_hotplug.lock (when running concurrently
      with CPU hotplug operations).
      
      Instead, the correct and race-free way of performing the callback
      registration is:
      
      	cpu_notifier_register_begin();
      
      	for_each_online_cpu(cpu)
      		init_cpu(cpu);
      
      	/* Note the use of the double underscored version of the API */
      	__register_cpu_notifier(&foobar_cpu_notifier);
      
      	cpu_notifier_register_done();
      
      Fix the hpet code in x86 by using this latter form of callback registration.
      
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: Ingo Molnar <mingo@kernel.org>
      Cc: "H. Peter Anvin" <hpa@zytor.com>
      Signed-off-by: NSrivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
      Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
      9014ad2a
    • S
      x86, amd, uncore: Fix CPU hotplug callback registration · a8c17c29
      Srivatsa S. Bhat 提交于
      Subsystems that want to register CPU hotplug callbacks, as well as perform
      initialization for the CPUs that are already online, often do it as shown
      below:
      
      	get_online_cpus();
      
      	for_each_online_cpu(cpu)
      		init_cpu(cpu);
      
      	register_cpu_notifier(&foobar_cpu_notifier);
      
      	put_online_cpus();
      
      This is wrong, since it is prone to ABBA deadlocks involving the
      cpu_add_remove_lock and the cpu_hotplug.lock (when running concurrently
      with CPU hotplug operations).
      
      Instead, the correct and race-free way of performing the callback
      registration is:
      
      	cpu_notifier_register_begin();
      
      	for_each_online_cpu(cpu)
      		init_cpu(cpu);
      
      	/* Note the use of the double underscored version of the API */
      	__register_cpu_notifier(&foobar_cpu_notifier);
      
      	cpu_notifier_register_done();
      
      Fix the amd-uncore code in x86 by using this latter form of callback
      registration.
      
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Paul Mackerras <paulus@samba.org>
      Cc: Ingo Molnar <mingo@kernel.org>
      Cc: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: "H. Peter Anvin" <hpa@zytor.com>
      Signed-off-by: NSrivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
      Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
      a8c17c29
    • S
      x86, intel, rapl: Fix CPU hotplug callback registration · fd537e56
      Srivatsa S. Bhat 提交于
      Subsystems that want to register CPU hotplug callbacks, as well as perform
      initialization for the CPUs that are already online, often do it as shown
      below:
      
      	get_online_cpus();
      
      	for_each_online_cpu(cpu)
      		init_cpu(cpu);
      
      	register_cpu_notifier(&foobar_cpu_notifier);
      
      	put_online_cpus();
      
      This is wrong, since it is prone to ABBA deadlocks involving the
      cpu_add_remove_lock and the cpu_hotplug.lock (when running concurrently
      with CPU hotplug operations).
      
      Instead, the correct and race-free way of performing the callback
      registration is:
      
      	cpu_notifier_register_begin();
      
      	for_each_online_cpu(cpu)
      		init_cpu(cpu);
      
      	/* Note the use of the double underscored version of the API */
      	__register_cpu_notifier(&foobar_cpu_notifier);
      
      	cpu_notifier_register_done();
      
      Fix the intel rapl code in x86 by using this latter form of callback
      registration.
      
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Paul Mackerras <paulus@samba.org>
      Cc: Ingo Molnar <mingo@kernel.org>
      Cc: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: "H. Peter Anvin" <hpa@zytor.com>
      Signed-off-by: NSrivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
      Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
      fd537e56
    • S
      x86, intel, cacheinfo: Fix CPU hotplug callback registration · 8c60ea14
      Srivatsa S. Bhat 提交于
      Subsystems that want to register CPU hotplug callbacks, as well as perform
      initialization for the CPUs that are already online, often do it as shown
      below:
      
      	get_online_cpus();
      
      	for_each_online_cpu(cpu)
      		init_cpu(cpu);
      
      	register_cpu_notifier(&foobar_cpu_notifier);
      
      	put_online_cpus();
      
      This is wrong, since it is prone to ABBA deadlocks involving the
      cpu_add_remove_lock and the cpu_hotplug.lock (when running concurrently
      with CPU hotplug operations).
      
      Instead, the correct and race-free way of performing the callback
      registration is:
      
      	cpu_notifier_register_begin();
      
      	for_each_online_cpu(cpu)
      		init_cpu(cpu);
      
      	/* Note the use of the double underscored version of the API */
      	__register_cpu_notifier(&foobar_cpu_notifier);
      
      	cpu_notifier_register_done();
      
      Fix the intel cacheinfo code in x86 by using this latter form of callback
      registration.
      
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: Ingo Molnar <mingo@kernel.org>
      Cc: "H. Peter Anvin" <hpa@zytor.com>
      Signed-off-by: NSrivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
      Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
      8c60ea14
    • S
      x86, amd, ibs: Fix CPU hotplug callback registration · 047868ce
      Srivatsa S. Bhat 提交于
      Subsystems that want to register CPU hotplug callbacks, as well as perform
      initialization for the CPUs that are already online, often do it as shown
      below:
      
      	get_online_cpus();
      
      	for_each_online_cpu(cpu)
      		init_cpu(cpu);
      
      	register_cpu_notifier(&foobar_cpu_notifier);
      
      	put_online_cpus();
      
      This is wrong, since it is prone to ABBA deadlocks involving the
      cpu_add_remove_lock and the cpu_hotplug.lock (when running concurrently
      with CPU hotplug operations).
      
      Instead, the correct and race-free way of performing the callback
      registration is:
      
      	cpu_notifier_register_begin();
      
      	for_each_online_cpu(cpu)
      		init_cpu(cpu);
      
      	/* Note the use of the double underscored version of the API */
      	__register_cpu_notifier(&foobar_cpu_notifier);
      
      	cpu_notifier_register_done();
      
      Fix the amd-ibs code in x86 by using this latter form of callback
      registration.
      
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Paul Mackerras <paulus@samba.org>
      Cc: Ingo Molnar <mingo@kernel.org>
      Cc: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: "H. Peter Anvin" <hpa@zytor.com>
      Signed-off-by: NSrivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
      Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
      047868ce
    • S
      x86, therm_throt.c: Remove unused therm_cpu_lock · 7b7139d4
      Srivatsa S. Bhat 提交于
      After fixing the CPU hotplug callback registration code, the callbacks
      invoked for each online CPU, during the initialization phase in
      thermal_throttle_init_device(), can no longer race with the actual CPU
      hotplug notifier callbacks (in thermal_throttle_cpu_callback). Hence the
      therm_cpu_lock is unnecessary now. Remove it.
      
      Cc: Tony Luck <tony.luck@intel.com>
      Cc: Borislav Petkov <bp@alien8.de>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: Ingo Molnar <mingo@kernel.org>
      Cc: "H. Peter Anvin" <hpa@zytor.com>
      Suggested-by: NOleg Nesterov <oleg@redhat.com>
      Signed-off-by: NSrivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
      Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
      7b7139d4
    • S
      x86, therm_throt.c: Fix CPU hotplug callback registration · 4e6192bb
      Srivatsa S. Bhat 提交于
      Subsystems that want to register CPU hotplug callbacks, as well as perform
      initialization for the CPUs that are already online, often do it as shown
      below:
      
      	get_online_cpus();
      
      	for_each_online_cpu(cpu)
      		init_cpu(cpu);
      
      	register_cpu_notifier(&foobar_cpu_notifier);
      
      	put_online_cpus();
      
      This is wrong, since it is prone to ABBA deadlocks involving the
      cpu_add_remove_lock and the cpu_hotplug.lock (when running concurrently
      with CPU hotplug operations).
      
      Instead, the correct and race-free way of performing the callback
      registration is:
      
      	cpu_notifier_register_begin();
      
      	for_each_online_cpu(cpu)
      		init_cpu(cpu);
      
      	/* Note the use of the double underscored version of the API */
      	__register_cpu_notifier(&foobar_cpu_notifier);
      
      	cpu_notifier_register_done();
      
      Fix the thermal throttle code in x86 by using this latter form of callback
      registration.
      
      Cc: Tony Luck <tony.luck@intel.com>
      Cc: Borislav Petkov <bp@alien8.de>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: Ingo Molnar <mingo@kernel.org>
      Cc: "H. Peter Anvin" <hpa@zytor.com>
      Signed-off-by: NSrivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
      Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
      4e6192bb
    • S
      x86, mce: Fix CPU hotplug callback registration · 82a8f131
      Srivatsa S. Bhat 提交于
      Subsystems that want to register CPU hotplug callbacks, as well as perform
      initialization for the CPUs that are already online, often do it as shown
      below:
      
      	get_online_cpus();
      
      	for_each_online_cpu(cpu)
      		init_cpu(cpu);
      
      	register_cpu_notifier(&foobar_cpu_notifier);
      
      	put_online_cpus();
      
      This is wrong, since it is prone to ABBA deadlocks involving the
      cpu_add_remove_lock and the cpu_hotplug.lock (when running concurrently
      with CPU hotplug operations).
      
      Instead, the correct and race-free way of performing the callback
      registration is:
      
      	cpu_notifier_register_begin();
      
      	for_each_online_cpu(cpu)
      		init_cpu(cpu);
      
      	/* Note the use of the double underscored version of the API */
      	__register_cpu_notifier(&foobar_cpu_notifier);
      
      	cpu_notifier_register_done();
      
      Fix the mce code in x86 by using this latter form of callback registration.
      
      Cc: Tony Luck <tony.luck@intel.com>
      Cc: Borislav Petkov <bp@alien8.de>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: Ingo Molnar <mingo@kernel.org>
      Cc: "H. Peter Anvin" <hpa@zytor.com>
      Signed-off-by: NSrivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
      Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
      82a8f131
    • S
      x86, intel, uncore: Fix CPU hotplug callback registration · 2c666ada
      Srivatsa S. Bhat 提交于
      Subsystems that want to register CPU hotplug callbacks, as well as perform
      initialization for the CPUs that are already online, often do it as shown
      below:
      
      	get_online_cpus();
      
      	for_each_online_cpu(cpu)
      		init_cpu(cpu);
      
      	register_cpu_notifier(&foobar_cpu_notifier);
      
      	put_online_cpus();
      
      This is wrong, since it is prone to ABBA deadlocks involving the
      cpu_add_remove_lock and the cpu_hotplug.lock (when running concurrently
      with CPU hotplug operations).
      
      Instead, the correct and race-free way of performing the callback
      registration is:
      
      	cpu_notifier_register_begin();
      
      	for_each_online_cpu(cpu)
      		init_cpu(cpu);
      
      	/* Note the use of the double underscored version of the API */
      	__register_cpu_notifier(&foobar_cpu_notifier);
      
      	cpu_notifier_register_done();
      
      Fix the uncore code in intel-x86 by using this latter form of callback
      registration.
      
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Paul Mackerras <paulus@samba.org>
      Cc: Ingo Molnar <mingo@kernel.org>
      Cc: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: "H. Peter Anvin" <hpa@zytor.com>
      Signed-off-by: NSrivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
      Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
      2c666ada
    • S
      x86, vsyscall: Fix CPU hotplug callback registration · 42112a0f
      Srivatsa S. Bhat 提交于
      Subsystems that want to register CPU hotplug callbacks, as well as perform
      initialization for the CPUs that are already online, often do it as shown
      below:
      
      	get_online_cpus();
      
      	for_each_online_cpu(cpu)
      		init_cpu(cpu);
      
      	register_cpu_notifier(&foobar_cpu_notifier);
      
      	put_online_cpus();
      
      This is wrong, since it is prone to ABBA deadlocks involving the
      cpu_add_remove_lock and the cpu_hotplug.lock (when running concurrently
      with CPU hotplug operations).
      
      Instead, the correct and race-free way of performing the callback
      registration is:
      
      	cpu_notifier_register_begin();
      
      	for_each_online_cpu(cpu)
      		init_cpu(cpu);
      
      	/* Note the use of the double underscored version of the API */
      	__register_cpu_notifier(&foobar_cpu_notifier);
      
      	cpu_notifier_register_done();
      
      Fix the vsyscall code in x86 by using this latter form of callback
      registration.
      
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: Ingo Molnar <mingo@kernel.org>
      Cc: "H. Peter Anvin" <hpa@zytor.com>
      Signed-off-by: NSrivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
      Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
      42112a0f
    • S
      x86, cpuid: Fix CPU hotplug callback registration · 4b660b38
      Srivatsa S. Bhat 提交于
      Subsystems that want to register CPU hotplug callbacks, as well as perform
      initialization for the CPUs that are already online, often do it as shown
      below:
      
      	get_online_cpus();
      
      	for_each_online_cpu(cpu)
      		init_cpu(cpu);
      
      	register_cpu_notifier(&foobar_cpu_notifier);
      
      	put_online_cpus();
      
      This is wrong, since it is prone to ABBA deadlocks involving the
      cpu_add_remove_lock and the cpu_hotplug.lock (when running concurrently
      with CPU hotplug operations).
      
      Instead, the correct and race-free way of performing the callback
      registration is:
      
      	cpu_notifier_register_begin();
      
      	for_each_online_cpu(cpu)
      		init_cpu(cpu);
      
      	/* Note the use of the double underscored version of the API */
      	__register_cpu_notifier(&foobar_cpu_notifier);
      
      	cpu_notifier_register_done();
      
      Fix the cpuid code in x86 by using this latter form of callback registration.
      
      Cc: "H. Peter Anvin" <hpa@zytor.com>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: Ingo Molnar <mingo@kernel.org>
      Signed-off-by: NSrivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
      Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
      4b660b38
    • S
      x86, msr: Fix CPU hotplug callback registration · de82a01b
      Srivatsa S. Bhat 提交于
      Subsystems that want to register CPU hotplug callbacks, as well as perform
      initialization for the CPUs that are already online, often do it as shown
      below:
      
      	get_online_cpus();
      
      	for_each_online_cpu(cpu)
      		init_cpu(cpu);
      
      	register_cpu_notifier(&foobar_cpu_notifier);
      
      	put_online_cpus();
      
      This is wrong, since it is prone to ABBA deadlocks involving the
      cpu_add_remove_lock and the cpu_hotplug.lock (when running concurrently
      with CPU hotplug operations).
      
      Instead, the correct and race-free way of performing the callback
      registration is:
      
      	cpu_notifier_register_begin();
      
      	for_each_online_cpu(cpu)
      		init_cpu(cpu);
      
      	/* Note the use of the double underscored version of the API */
      	__register_cpu_notifier(&foobar_cpu_notifier);
      
      	cpu_notifier_register_done();
      
      Fix the msr code in x86 by using this latter form of callback registration.
      
      Cc: "H. Peter Anvin" <hpa@zytor.com>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: Ingo Molnar <mingo@kernel.org>
      Signed-off-by: NSrivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
      Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
      de82a01b
    • S
      powerpc, sysfs: Fix CPU hotplug callback registration · d1a55113
      Srivatsa S. Bhat 提交于
      Subsystems that want to register CPU hotplug callbacks, as well as perform
      initialization for the CPUs that are already online, often do it as shown
      below:
      
      	get_online_cpus();
      
      	for_each_online_cpu(cpu)
      		init_cpu(cpu);
      
      	register_cpu_notifier(&foobar_cpu_notifier);
      
      	put_online_cpus();
      
      This is wrong, since it is prone to ABBA deadlocks involving the
      cpu_add_remove_lock and the cpu_hotplug.lock (when running concurrently
      with CPU hotplug operations).
      
      Instead, the correct and race-free way of performing the callback
      registration is:
      
      	cpu_notifier_register_begin();
      
      	for_each_online_cpu(cpu)
      		init_cpu(cpu);
      
      	/* Note the use of the double underscored version of the API */
      	__register_cpu_notifier(&foobar_cpu_notifier);
      
      	cpu_notifier_register_done();
      
      Fix the sysfs code in powerpc by using this latter form of callback
      registration.
      
      Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
      Cc: Paul Mackerras <paulus@samba.org>
      Cc: Olof Johansson <olof@lixom.net>
      Cc: Wang Dongsheng <dongsheng.wang@freescale.com>
      Cc: Ingo Molnar <mingo@kernel.org>
      Acked-by: NMadhavan Srinivasan <maddy@linux.vnet.ibm.com>
      Signed-off-by: NSrivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
      Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
      d1a55113
    • S
      sparc, sysfs: Fix CPU hotplug callback registration · 1e0b0c4c
      Srivatsa S. Bhat 提交于
      Subsystems that want to register CPU hotplug callbacks, as well as perform
      initialization for the CPUs that are already online, often do it as shown
      below:
      
      	get_online_cpus();
      
      	for_each_online_cpu(cpu)
      		init_cpu(cpu);
      
      	register_cpu_notifier(&foobar_cpu_notifier);
      
      	put_online_cpus();
      
      This is wrong, since it is prone to ABBA deadlocks involving the
      cpu_add_remove_lock and the cpu_hotplug.lock (when running concurrently
      with CPU hotplug operations).
      
      Instead, the correct and race-free way of performing the callback
      registration is:
      
      	cpu_notifier_register_begin();
      
      	for_each_online_cpu(cpu)
      		init_cpu(cpu);
      
      	/* Note the use of the double underscored version of the API */
      	__register_cpu_notifier(&foobar_cpu_notifier);
      
      	cpu_notifier_register_done();
      
      Fix the sysfs code in sparc by using this latter form of callback
      registration.
      
      Cc: Ingo Molnar <mingo@kernel.org>
      Acked-by: NDavid S. Miller <davem@davemloft.net>
      Signed-off-by: NSrivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
      Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
      1e0b0c4c
    • S
      s390, smp: Fix CPU hotplug callback registration · f4edbcd5
      Srivatsa S. Bhat 提交于
      Subsystems that want to register CPU hotplug callbacks, as well as perform
      initialization for the CPUs that are already online, often do it as shown
      below:
      
      	get_online_cpus();
      
      	for_each_online_cpu(cpu)
      		init_cpu(cpu);
      
      	register_cpu_notifier(&foobar_cpu_notifier);
      
      	put_online_cpus();
      
      This is wrong, since it is prone to ABBA deadlocks involving the
      cpu_add_remove_lock and the cpu_hotplug.lock (when running concurrently
      with CPU hotplug operations).
      
      Instead, the correct and race-free way of performing the callback
      registration is:
      
      	cpu_notifier_register_begin();
      
      	for_each_online_cpu(cpu)
      		init_cpu(cpu);
      
      	/* Note the use of the double underscored version of the API */
      	__register_cpu_notifier(&foobar_cpu_notifier);
      
      	cpu_notifier_register_done();
      
      Fix the smp code in s390 by using this latter form of callback registration.
      
      Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
      Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: Ingo Molnar <mingo@kernel.org>
      Signed-off-by: NSrivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
      Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
      f4edbcd5
    • S
      s390, cacheinfo: Fix CPU hotplug callback registration · 6575080e
      Srivatsa S. Bhat 提交于
      Subsystems that want to register CPU hotplug callbacks, as well as perform
      initialization for the CPUs that are already online, often do it as shown
      below:
      
      	get_online_cpus();
      
      	for_each_online_cpu(cpu)
      		init_cpu(cpu);
      
      	register_cpu_notifier(&foobar_cpu_notifier);
      
      	put_online_cpus();
      
      This is wrong, since it is prone to ABBA deadlocks involving the
      cpu_add_remove_lock and the cpu_hotplug.lock (when running concurrently
      with CPU hotplug operations).
      
      Instead, the correct and race-free way of performing the callback
      registration is:
      
      	cpu_notifier_register_begin();
      
      	for_each_online_cpu(cpu)
      		init_cpu(cpu);
      
      	/* Note the use of the double underscored version of the API */
      	__register_cpu_notifier(&foobar_cpu_notifier);
      
      	cpu_notifier_register_done();
      
      Fix the cacheinfo code in s390 by using this latter form of callback
      registration.
      
      Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
      Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
      Cc: Ingo Molnar <mingo@kernel.org>
      Signed-off-by: NSrivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
      Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
      6575080e
    • S
      arm, kvm: Fix CPU hotplug callback registration · 8146875d
      Srivatsa S. Bhat 提交于
      On 03/15/2014 12:40 AM, Christoffer Dall wrote:
      > On Fri, Mar 14, 2014 at 11:13:29AM +0530, Srivatsa S. Bhat wrote:
      >> On 03/13/2014 04:51 AM, Christoffer Dall wrote:
      >>> On Tue, Mar 11, 2014 at 02:05:38AM +0530, Srivatsa S. Bhat wrote:
      >>>> Subsystems that want to register CPU hotplug callbacks, as well as perform
      >>>> initialization for the CPUs that are already online, often do it as shown
      >>>> below:
      >>>>
      [...]
      >>> Just so we're clear, the existing code was simply racy as not prone to
      >>> deadlocks, right?
      
      > >>> This makes it clear that the test above for compatible CPUs can be quite
      > >>> easily evaded by using CPU hotplug, but we don't really have a good
      > >>> solution for handling that yet...  Hmmm, grumble grumble, I guess if you
      > >>> hotplug unsupported CPUs on a KVM/ARM system for now, stuff will break.
      
      >>
      >> In this particular case, there was no deadlock possibility, rather the
      >> existing code had insufficient synchronization against CPU hotplug.
      >>
      >> init_hyp_mode() would invoke cpu_init_hyp_mode() on currently online CPUs
      >> using on_each_cpu(). If a CPU came online after this point and before calling
      >> register_cpu_notifier(), that CPU would remain uninitialized because this
      >> subsystem would miss the hot-online event. This patch fixes this bug and
      >> also uses the new synchronization method (instead of get/put_online_cpus())
      >> to ensure that we don't deadlock with CPU hotplug.
      >>
      >
      > Yes, that was my conclusion as well.  Thanks for clarifying.  (It could
      > be noted in the commit message as well if you should feel so inclined).
      >
      
      Please find the patch with updated changelog (and your Ack) below.
      (No changes in code).
      
      From: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
      Subject: [PATCH] arm, kvm: Fix CPU hotplug callback registration
      
      Subsystems that want to register CPU hotplug callbacks, as well as perform
      initialization for the CPUs that are already online, often do it as shown
      below:
      
      	get_online_cpus();
      
      	for_each_online_cpu(cpu)
      		init_cpu(cpu);
      
      	register_cpu_notifier(&foobar_cpu_notifier);
      
      	put_online_cpus();
      
      This is wrong, since it is prone to ABBA deadlocks involving the
      cpu_add_remove_lock and the cpu_hotplug.lock (when running concurrently
      with CPU hotplug operations).
      
      Instead, the correct and race-free way of performing the callback
      registration is:
      
      	cpu_notifier_register_begin();
      
      	for_each_online_cpu(cpu)
      		init_cpu(cpu);
      
      	/* Note the use of the double underscored version of the API */
      	__register_cpu_notifier(&foobar_cpu_notifier);
      
      	cpu_notifier_register_done();
      
      In the existing arm kvm code, there is no synchronization with CPU hotplug
      to avoid missing the hotplug events that might occur after invoking
      init_hyp_mode() and before calling register_cpu_notifier(). Fix this bug
      and also use the new synchronization method (instead of get/put_online_cpus())
      to ensure that we don't deadlock with CPU hotplug.
      
      Cc: Gleb Natapov <gleb@kernel.org>
      Cc: Russell King <linux@arm.linux.org.uk>
      Cc: Ingo Molnar <mingo@kernel.org>
      Acked-by: NPaolo Bonzini <pbonzini@redhat.com>
      Acked-by: NChristoffer Dall <christoffer.dall@linaro.org>
      Signed-off-by: NSrivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
      Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
      8146875d
    • S
      arm, hw-breakpoint: Fix CPU hotplug callback registration · c5929bd3
      Srivatsa S. Bhat 提交于
      Subsystems that want to register CPU hotplug callbacks, as well as perform
      initialization for the CPUs that are already online, often do it as shown
      below:
      
      	get_online_cpus();
      
      	for_each_online_cpu(cpu)
      		init_cpu(cpu);
      
      	register_cpu_notifier(&foobar_cpu_notifier);
      
      	put_online_cpus();
      
      This is wrong, since it is prone to ABBA deadlocks involving the
      cpu_add_remove_lock and the cpu_hotplug.lock (when running concurrently
      with CPU hotplug operations).
      
      Instead, the correct and race-free way of performing the callback
      registration is:
      
      	cpu_notifier_register_begin();
      
      	for_each_online_cpu(cpu)
      		init_cpu(cpu);
      
      	/* Note the use of the double underscored version of the API */
      	__register_cpu_notifier(&foobar_cpu_notifier);
      
      	cpu_notifier_register_done();
      
      Fix the hw-breakpoint code in arm by using this latter form of callback
      registration.
      
      Cc: Russell King <linux@arm.linux.org.uk>
      Cc: Ingo Molnar <mingo@kernel.org>
      Acked-by: NWill Deacon <will.deacon@arm.com>
      Signed-off-by: NSrivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
      Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
      c5929bd3
    • S
      ia64, err-inject: Fix CPU hotplug callback registration · f2e48a89
      Srivatsa S. Bhat 提交于
      Subsystems that want to register CPU hotplug callbacks, as well as perform
      initialization for the CPUs that are already online, often do it as shown
      below:
      
      	get_online_cpus();
      
      	for_each_online_cpu(cpu)
      		init_cpu(cpu);
      
      	register_cpu_notifier(&foobar_cpu_notifier);
      
      	put_online_cpus();
      
      This is wrong, since it is prone to ABBA deadlocks involving the
      cpu_add_remove_lock and the cpu_hotplug.lock (when running concurrently
      with CPU hotplug operations).
      
      Instead, the correct and race-free way of performing the callback
      registration is:
      
      	cpu_notifier_register_begin();
      
      	for_each_online_cpu(cpu)
      		init_cpu(cpu);
      
      	/* Note the use of the double underscored version of the API */
      	__register_cpu_notifier(&foobar_cpu_notifier);
      
      	cpu_notifier_register_done();
      
      Fix the error injection code in ia64 by using this latter form of callback
      registration.
      
      Cc: Tony Luck <tony.luck@intel.com>
      Cc: Fenghua Yu <fenghua.yu@intel.com>
      Cc: Ingo Molnar <mingo@kernel.org>
      Signed-off-by: NSrivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
      Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
      f2e48a89
    • S
      ia64, topology: Fix CPU hotplug callback registration · f5a7d445
      Srivatsa S. Bhat 提交于
      Subsystems that want to register CPU hotplug callbacks, as well as perform
      initialization for the CPUs that are already online, often do it as shown
      below:
      
      	get_online_cpus();
      
      	for_each_online_cpu(cpu)
      		init_cpu(cpu);
      
      	register_cpu_notifier(&foobar_cpu_notifier);
      
      	put_online_cpus();
      
      This is wrong, since it is prone to ABBA deadlocks involving the
      cpu_add_remove_lock and the cpu_hotplug.lock (when running concurrently
      with CPU hotplug operations).
      
      Instead, the correct and race-free way of performing the callback
      registration is:
      
      	cpu_notifier_register_begin();
      
      	for_each_online_cpu(cpu)
      		init_cpu(cpu);
      
      	/* Note the use of the double underscored version of the API */
      	__register_cpu_notifier(&foobar_cpu_notifier);
      
      	cpu_notifier_register_done();
      
      Fix the topology code in ia64 by using this latter form of callback
      registration.
      
      Cc: Tony Luck <tony.luck@intel.com>
      Cc: Fenghua Yu <fenghua.yu@intel.com>
      Cc: Ingo Molnar <mingo@kernel.org>
      Signed-off-by: NSrivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
      Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
      f5a7d445
    • S
      ia64, palinfo: Fix CPU hotplug callback registration · 9f37bca9
      Srivatsa S. Bhat 提交于
      Subsystems that want to register CPU hotplug callbacks, as well as perform
      initialization for the CPUs that are already online, often do it as shown
      below:
      
      	get_online_cpus();
      
      	for_each_online_cpu(cpu)
      		init_cpu(cpu);
      
      	register_cpu_notifier(&foobar_cpu_notifier);
      
      	put_online_cpus();
      
      This is wrong, since it is prone to ABBA deadlocks involving the
      cpu_add_remove_lock and the cpu_hotplug.lock (when running concurrently
      with CPU hotplug operations).
      
      Instead, the correct and race-free way of performing the callback
      registration is:
      
      	cpu_notifier_register_begin();
      
      	for_each_online_cpu(cpu)
      		init_cpu(cpu);
      
      	/* Note the use of the double underscored version of the API */
      	__register_cpu_notifier(&foobar_cpu_notifier);
      
      	cpu_notifier_register_done();
      
      Fix the palinfo code in ia64 by using this latter form of callback
      registration.
      
      Cc: Tony Luck <tony.luck@intel.com>
      Cc: Fenghua Yu <fenghua.yu@intel.com>
      Cc: Ingo Molnar <mingo@kernel.org>
      Signed-off-by: NSrivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
      Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
      9f37bca9
    • S
      ia64, salinfo: Fix hotplug callback registration · eff722b0
      Srivatsa S. Bhat 提交于
      Subsystems that want to register CPU hotplug callbacks, as well as perform
      initialization for the CPUs that are already online, often do it as shown
      below:
      
      	get_online_cpus();
      
      	for_each_online_cpu(cpu)
      		init_cpu(cpu);
      
      	register_cpu_notifier(&foobar_cpu_notifier);
      
      	put_online_cpus();
      
      This is wrong, since it is prone to ABBA deadlocks involving the
      cpu_add_remove_lock and the cpu_hotplug.lock (when running concurrently
      with CPU hotplug operations).
      
      Instead, the correct and race-free way of performing the callback
      registration is:
      
      	cpu_notifier_register_begin();
      
      	for_each_online_cpu(cpu)
      		init_cpu(cpu);
      
      	/* Note the use of the double underscored version of the API */
      	__register_cpu_notifier(&foobar_cpu_notifier);
      
      	cpu_notifier_register_done();
      
      Fix the salinfo code in ia64 by using this latter form of callback
      registration.
      
      Cc: Tony Luck <tony.luck@intel.com>
      Cc: Fenghua Yu <fenghua.yu@intel.com>
      Cc: Ingo Molnar <mingo@kernel.org>
      Signed-off-by: NSrivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
      Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
      eff722b0
    • S
      CPU hotplug, perf: Fix CPU hotplug callback registration · f0bdb5e0
      Srivatsa S. Bhat 提交于
      Subsystems that want to register CPU hotplug callbacks, as well as perform
      initialization for the CPUs that are already online, often do it as shown
      below:
      
      	get_online_cpus();
      
      	for_each_online_cpu(cpu)
      		init_cpu(cpu);
      
      	register_cpu_notifier(&foobar_cpu_notifier);
      
      	put_online_cpus();
      
      This is wrong, since it is prone to ABBA deadlocks involving the
      cpu_add_remove_lock and the cpu_hotplug.lock (when running concurrently
      with CPU hotplug operations).
      
      Instead, the correct and race-free way of performing the callback
      registration is:
      
      	cpu_notifier_register_begin();
      
      	for_each_online_cpu(cpu)
      		init_cpu(cpu);
      
      	/* Note the use of the double underscored version of the API */
      	__register_cpu_notifier(&foobar_cpu_notifier);
      
      	cpu_notifier_register_done();
      
      Fix the perf subsystem's hotplug notifier by using this latter form of
      callback registration.
      
      Also provide a bare-bones version of perf_cpu_notifier() that doesn't
      invoke the notifiers for the already online CPUs. This would be useful
      for subsystems that need to perform a different set of initialization
      for the already online CPUs, or don't need the initialization altogether.
      
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Paul Mackerras <paulus@samba.org>
      Cc: Ingo Molnar <mingo@kernel.org>
      Cc: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
      Signed-off-by: NSrivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
      Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
      f0bdb5e0
    • S
      Doc/cpu-hotplug: Specify race-free way to register CPU hotplug callbacks · 8489d90b
      Srivatsa S. Bhat 提交于
      Recommend the usage of the new CPU hotplug callback registration APIs
      (__register_cpu_notifier() etc), when subsystems need to also perform
      initialization for already online CPUs. Provide examples of correct
      and race-free ways of achieving this, and point out the kinds of code
      that are error-prone.
      
      Cc: Rob Landley <rob@landley.net>
      Cc: Ingo Molnar <mingo@kernel.org>
      Signed-off-by: NSrivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
      Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
      8489d90b
    • S
      CPU hotplug: Provide lockless versions of callback registration functions · 93ae4f97
      Srivatsa S. Bhat 提交于
      The following method of CPU hotplug callback registration is not safe
      due to the possibility of an ABBA deadlock involving the cpu_add_remove_lock
      and the cpu_hotplug.lock.
      
      	get_online_cpus();
      
      	for_each_online_cpu(cpu)
      		init_cpu(cpu);
      
      	register_cpu_notifier(&foobar_cpu_notifier);
      
      	put_online_cpus();
      
      The deadlock is shown below:
      
                CPU 0                                         CPU 1
                -----                                         -----
      
         Acquire cpu_hotplug.lock
         [via get_online_cpus()]
      
                                                    CPU online/offline operation
                                                    takes cpu_add_remove_lock
                                                    [via cpu_maps_update_begin()]
      
         Try to acquire
         cpu_add_remove_lock
         [via register_cpu_notifier()]
      
                                                    CPU online/offline operation
                                                    tries to acquire cpu_hotplug.lock
                                                    [via cpu_hotplug_begin()]
      
                                  *** DEADLOCK! ***
      
      The problem here is that callback registration takes the locks in one order
      whereas the CPU hotplug operations take the same locks in the opposite order.
      To avoid this issue and to provide a race-free method to register CPU hotplug
      callbacks (along with initialization of already online CPUs), introduce new
      variants of the callback registration APIs that simply register the callbacks
      without holding the cpu_add_remove_lock during the registration. That way,
      we can avoid the ABBA scenario. However, we will need to hold the
      cpu_add_remove_lock throughout the entire critical section, to protect updates
      to the callback/notifier chain.
      
      This can be achieved by writing the callback registration code as follows:
      
      	cpu_maps_update_begin(); [ or cpu_notifier_register_begin(); see below ]
      
      	for_each_online_cpu(cpu)
      		init_cpu(cpu);
      
      	/* This doesn't take the cpu_add_remove_lock */
      	__register_cpu_notifier(&foobar_cpu_notifier);
      
      	cpu_maps_update_done();  [ or cpu_notifier_register_done(); see below ]
      
      Note that we can't use get_online_cpus() here instead of cpu_maps_update_begin()
      because the cpu_hotplug.lock is dropped during the invocation of CPU_POST_DEAD
      notifiers, and hence get_online_cpus() cannot provide the necessary
      synchronization to protect the callback/notifier chains against concurrent
      reads and writes. On the other hand, since the cpu_add_remove_lock protects
      the entire hotplug operation (including CPU_POST_DEAD), we can use
      cpu_maps_update_begin/done() to guarantee proper synchronization.
      
      Also, since cpu_maps_update_begin/done() is like a super-set of
      get/put_online_cpus(), the former naturally protects the critical sections
      from concurrent hotplug operations.
      
      Since the names cpu_maps_update_begin/done() don't make much sense in CPU
      hotplug callback registration scenarios, we'll introduce new APIs named
      cpu_notifier_register_begin/done() and map them to cpu_maps_update_begin/done().
      
      In summary, introduce the lockless variants of un/register_cpu_notifier() and
      also export the cpu_notifier_register_begin/done() APIs for use by modules.
      This way, we provide a race-free way to register hotplug callbacks as well as
      perform initialization for the CPUs that are already online.
      
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: Andrew Morton <akpm@linux-foundation.org>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Ingo Molnar <mingo@kernel.org>
      Acked-by: NOleg Nesterov <oleg@redhat.com>
      Acked-by: NToshi Kani <toshi.kani@hp.com>
      Reviewed-by: NGautham R. Shenoy <ego@linux.vnet.ibm.com>
      Signed-off-by: NSrivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
      Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
      93ae4f97
    • G
      CPU hotplug: Add lockdep annotations to get/put_online_cpus() · a19423b9
      Gautham R. Shenoy 提交于
      Add lockdep annotations for get/put_online_cpus() and
      cpu_hotplug_begin()/cpu_hotplug_end().
      
      Cc: Ingo Molnar <mingo@kernel.org>
      Reviewed-by: NOleg Nesterov <oleg@redhat.com>
      Signed-off-by: NGautham R. Shenoy <ego@linux.vnet.ibm.com>
      Signed-off-by: NSrivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
      Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
      a19423b9
  2. 17 3月, 2014 4 次提交
    • L
      Linux 3.14-rc7 · dcb99fd9
      Linus Torvalds 提交于
      dcb99fd9
    • L
      Merge branch 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip · 59bf6c3c
      Linus Torvalds 提交于
      Pull scheduler fixes from Ingo Molnar:
       "Three small fixes"
      
      * 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
        sched/clock: Prevent tracing recursion in sched_clock_cpu()
        stop_machine: Fix^2 race between stop_two_cpus() and stop_cpus()
        sched/deadline: Deny unprivileged users to set/change SCHED_DEADLINE policy
      59bf6c3c
    • L
      Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip · b44eeb4d
      Linus Torvalds 提交于
      Pull perf fixes from Ingo Molnar:
       "Misc smaller fixes"
      
      * 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
        perf/x86: Fix leak in uncore_type_init failure paths
        perf machine: Use map as success in ip__resolve_ams
        perf symbols: Fix crash in elf_section_by_name
        perf trace: Decode architecture-specific signal numbers
      b44eeb4d
    • M
      ipc: Fix 2 bugs in msgrcv() MSG_COPY implementation · 4f87dac3
      Michael Kerrisk 提交于
      While testing and documenting the msgrcv() MSG_COPY flag that Stanislav
      Kinsbursky added in commit 4a674f34 ("ipc: introduce message queue
      copy feature" => kernel 3.8), I discovered a couple of bugs in the
      implementation.  The two bugs concern MSG_COPY interactions with other
      msgrcv() flags, namely:
      
       (A) MSG_COPY + MSG_EXCEPT
       (B) MSG_COPY + !IPC_NOWAIT
      
      The bugs are distinct (and the fix for the first one is obvious),
      however my fix for both is a single-line patch, which is why I'm
      combining them in a single mail, rather than writing two mails+patches.
      
       ===== (A) MSG_COPY + MSG_EXCEPT =====
      
      With the addition of the MSG_COPY flag, there are now two msgrcv()
      flags--MSG_COPY and MSG_EXCEPT--that modify the meaning of the 'msgtyp'
      argument in unrelated ways.  Specifying both in the same call is a
      logical error that is currently permitted, with the effect that MSG_COPY
      has priority and MSG_EXCEPT is ignored.  The call should give an error
      if both flags are specified.  The patch below implements that behavior.
      
       ===== (B) (B) MSG_COPY + !IPC_NOWAIT =====
      
      The test code that was submitted in commit 3a665531 ("selftests: IPC
      message queue copy feature test") shows MSG_COPY being used in
      conjunction with IPC_NOWAIT.  In other words, if there is no message at
      the position 'msgtyp'.  return immediately with the error in ENOMSG.
      
      What was not (fully) tested is the behavior if MSG_COPY is specified
      *without* IPC_NOWAIT, and there is an odd behavior.  If the queue
      contains less than 'msgtyp' messages, then the call blocks until the
      next message is written to the queue.  At that point, the msgrcv() call
      returns a copy of the newly added message, regardless of whether that
      message is at the ordinal position 'msgtyp'.  This is clearly bogus, and
      problematic for applications that might want to make use of the MSG_COPY
      flag.
      
      I considered the following possible solutions to this problem:
      
       (1) Force the call to block until a message *does* appear at the
           position 'msgtyp'.
      
       (2) If the MSG_COPY flag is specified, the kernel should implicitly add
           IPC_NOWAIT, so that the call fails with ENOMSG for this case.
      
       (3) If the MSG_COPY flag is specified, but IPC_NOWAIT is not, generate
           an error (probably, EINVAL is the right one).
      
      I do not know if any application would really want to have the
      functionality of solution (1), especially since an application can
      determine in advance the number of messages in the queue using msgctl()
      IPC_STAT.  Obviously, this solution would be the most work to implement.
      
      Solution (2) would have the effect of silently fixing any applications
      that tried to employ broken behavior.  However, it would mean that if we
      later decided to implement solution (1), then user-space could not
      easily detect what the kernel supports (but, since I'm somewhat doubtful
      that solution (1) is needed, I'm not sure that this is much of a
      problem).
      
      Solution (3) would have the effect of informing broken applications that
      they are doing something broken.  The downside is that this would cause
      a ABI breakage for any applications that are currently employing the
      broken behavior.  However:
      
      a) Those applications are almost certainly not getting the results they
         expect.
      b) Possibly, those applications don't even exist, because MSG_COPY is
         currently hidden behind CONFIG_CHECKPOINT_RESTORE.
      
      The upside of solution (3) is that if we later decided to implement
      solution (1), user-space could determine what the kernel supports, via
      the error return.
      
      In my view, solution (3) is mildly preferable to solution (2), and
      solution (1) could still be done later if anyone really cares.  The
      patch below implements solution (3).
      
      PS.  For anyone out there still listening, it's the usual story:
      documenting an API (and the thinking about, and the testing of the API,
      that documentation entails) is the one of the single best ways of
      finding bugs in the API, as I've learned from a lot of experience.  Best
      to do that documentation before releasing the API.
      Signed-off-by: NMichael Kerrisk <mtk.manpages@gmail.com>
      Acked-by: NStanislav Kinsbursky <skinsbursky@parallels.com>
      Cc: Stanislav Kinsbursky <skinsbursky@parallels.com>
      Cc: stable@vger.kernel.org
      Cc: Serge Hallyn <serge.hallyn@canonical.com>
      Cc: "Eric W. Biederman" <ebiederm@xmission.com>
      Cc: Pavel Emelyanov <xemul@parallels.com>
      Cc: Al Viro <viro@zeniv.linux.org.uk>
      Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      4f87dac3
  3. 16 3月, 2014 1 次提交
    • L
      Merge tag 'scsi-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi · 3b4df68d
      Linus Torvalds 提交于
      Pull SCSI fixes from James Bottomley:
       "This is a set of six fixes.  Two are instant crash/null deref types
        (storvsc and isci).  The two qla2xxx are initialisation problems that
        cause MSI-X failures and card misdetection, the isci erroneous macro
        is actually illegal C that's causing a miscompile with certain gcc
        versions and the be2iscsi bad if expression is a static checker fix"
      
      * tag 'scsi-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi:
        [SCSI] storvsc: NULL pointer dereference fix
        [SCSI] qla2xxx: Poll during initialization for ISP25xx and ISP83xx
        [SCSI] isci: correct erroneous for_each_isci_host macro
        [SCSI] isci: fix reset timeout handling
        [SCSI] be2iscsi: fix bad if expression
        [SCSI] qla2xxx: Fix multiqueue MSI-X registration.
      3b4df68d
  4. 15 3月, 2014 3 次提交
    • L
      Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip · a4ecdf82
      Linus Torvalds 提交于
      Pull x86 fixes from Peter Anvin:
       "Two x86 fixes: Suresh's eager FPU fix, and a fix to the NUMA quirk for
        AMD northbridges.
      
        This only includes Suresh's fix patch, not the "mostly a cleanup"
        patch which had __init issues"
      
      * 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
        x86/amd/numa: Fix northbridge quirk to assign correct NUMA node
        x86, fpu: Check tsk_used_math() in kernel_fpu_end() for eager FPU
      a4ecdf82
    • L
      Merge tag 'pm+acpi-3.14-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm · cee152ff
      Linus Torvalds 提交于
      Pull ACPI and power management fixes from Rafael Wysocki:
       "Three of these are regression fixes, for two recent regressions and
        one introduced during the 3.13 cycle, and the fourth one is a working
        version of the fix that had to be reverted last time.
      
        Specifics:
      
         - A recent ACPI resources handling fix overlooked the fact that it
           had to update the ACPI PNP subsystem's resources parsing too and
           caused confusing warning messages to be printed during system
           intialization on some systems (with arguably buggy ACPI tables).
           Fix from Zhang Rui.
      
         - Moving the early ACPI initialization before timekeeping_init()
           earlier in this cycle broke fast TSC calibration on at least one
           system, so it needs to be done later, but still before
           efi_enter_virtual_mode() to allow the EFI initialization to refer
           to ACPI.
      
         - A change related to code duplication reduction in the cpufreq core
           inadvertently caused cpufreq intialization to fail for some CPUs
           handled by intel_pstate by adding checks that may fail for that
           driver, but aren't even necessary when it is used.  The issue is
           addressed by preventing those checks from run in the configurations
           in which they aren't needed.
      
         - If the Hardware Reduced ACPI flag is set in the ACPI tables, system
           suspend, hibernation and ACPI power off will only work when special
           sleep control and sleep status registeres are provided (their
           addresses in the ACPI tables are not zero).  If those registers are
           not available, the features in question have no chances to work, so
           they shouldn't even be regarded as supported.  That helps with
           power off in particular, because alternative power off methods may
           be used then and they may actually work"
      
      * tag 'pm+acpi-3.14-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
        ACPI / sleep: Add extra checks for HW Reduced ACPI mode sleep states
        ACPI / init: Invoke early ACPI initialization later
        cpufreq: Skip current frequency initialization for ->setpolicy drivers
        PNP / ACPI: proper handling of ACPI IO/Memory resource parsing failures
      cee152ff
    • L
      Merge tag 'dm-3.14-fixes-4' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm · 0c01b452
      Linus Torvalds 提交于
      Pull device-mapper fixes form Mike Snitzer:
       "Two small fixes for the DM cache target:
      
         - fix corruption with >2TB fast device due to truncation bug
         - fix access beyond end of origin device due to a partial block"
      
      * tag 'dm-3.14-fixes-4' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm:
        dm cache: fix access beyond end of origin device
        dm cache: fix truncation bug when copying a block to/from >2TB fast device
      0c01b452
  5. 14 3月, 2014 1 次提交