- 12 12月, 2011 28 次提交
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由 Paul E. McKenney 提交于
Currently, RCU does not permit a CPU to enter dyntick-idle mode if that CPU has any RCU callbacks queued. This means that workloads for which each CPU wakes up and does some RCU updates every few ticks will never enter dyntick-idle mode. This can result in significant unnecessary power consumption, so this patch permits a given to enter dyntick-idle mode if it has callbacks, but only if that same CPU has completed all current work for the RCU core. We determine use rcu_pending() to determine whether a given CPU has completed all current work for the RCU core. Signed-off-by: NPaul E. McKenney <paul.mckenney@linaro.org> Signed-off-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com>
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由 Paul E. McKenney 提交于
The current code just complains if the current task is not the idle task. This commit therefore adds printing of the identity of the idle task. Signed-off-by: NPaul E. McKenney <paul.mckenney@linaro.org> Signed-off-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: NJosh Triplett <josh@joshtriplett.org>
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由 Paul E. McKenney 提交于
The trace_rcu_dyntick() trace event did not print both the old and the new value of the nesting level, and furthermore printed only the low-order 32 bits of it. This could result in some confusion when interpreting trace-event dumps, so this commit prints both the old and the new value, prints the full 64 bits, and also selects the process-entry/exit increment to print nicely in hexadecimal. Signed-off-by: NPaul E. McKenney <paul.mckenney@linaro.org> Signed-off-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: NJosh Triplett <josh@joshtriplett.org>
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由 Paul E. McKenney 提交于
Update various files in Documentation/RCU to reflect srcu_read_lock_raw() and srcu_read_unlock_raw(). Credit to Peter Zijlstra for suggesting use of the existing _raw suffix instead of the earlier bulkref names. Signed-off-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com>
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由 Paul E. McKenney 提交于
The RCU implementations, including SRCU, are designed to be used in a lock-like fashion, so that the read-side lock and unlock primitives must execute in the same context for any given read-side critical section. This constraint is enforced by lockdep-RCU. However, there is a need to enter an SRCU read-side critical section within the context of an exception and then exit in the context of the task that encountered the exception. The cost of this capability is that the read-side operations incur the overhead of disabling interrupts. Note that although the current implementation allows a given read-side critical section to be entered by one task and then exited by another, all known possible implementations that allow this have scalability problems. Therefore, a given read-side critical section must be exited by the same task that entered it, though perhaps from an interrupt or exception handler running within that task's context. But if you are thinking in terms of interrupt handlers, make sure that you have considered the possibility of threaded interrupt handlers. Credit goes to Peter Zijlstra for suggesting use of the existing _raw suffix to indicate disabling lockdep over the earlier "bulkref" names. Requested-by: NSrikar Dronamraju <srikar@linux.vnet.ibm.com> Signed-off-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com> Tested-by: NSrikar Dronamraju <srikar@linux.vnet.ibm.com>
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由 Paul E. McKenney 提交于
The PowerPC pSeries platform (CONFIG_PPC_PSERIES=y) enables hypervisor-call tracing for CONFIG_TRACEPOINTS=y kernels. One of the hypervisor calls that is traced is the H_CEDE call in the idle loop that tells the hypervisor that this OS instance no longer needs the current CPU. However, tracing uses RCU, so this combination of kernel configuration variables needs to avoid telling RCU about the current CPU's idleness until after the H_CEDE-entry tracing completes on the one hand, and must tell RCU that the the current CPU is no longer idle before the H_CEDE-exit tracing starts. In all other cases, it suffices to inform RCU of CPU idleness upon idle-loop entry and exit. This commit makes the required adjustments. Signed-off-by: NPaul E. McKenney <paul.mckenney@linaro.org> Signed-off-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: NJosh Triplett <josh@joshtriplett.org>
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由 Frederic Weisbecker 提交于
On the irq exit path, tick_nohz_irq_exit() may raise a softirq, which action leads to the wake up path and select_task_rq_fair() that makes use of rcu to iterate the domains. This is an illegal use of RCU because we may be in RCU extended quiescent state if we interrupted an RCU-idle window in the idle loop: [ 132.978883] =============================== [ 132.978883] [ INFO: suspicious RCU usage. ] [ 132.978883] ------------------------------- [ 132.978883] kernel/sched_fair.c:1707 suspicious rcu_dereference_check() usage! [ 132.978883] [ 132.978883] other info that might help us debug this: [ 132.978883] [ 132.978883] [ 132.978883] rcu_scheduler_active = 1, debug_locks = 0 [ 132.978883] RCU used illegally from extended quiescent state! [ 132.978883] 2 locks held by swapper/0: [ 132.978883] #0: (&p->pi_lock){-.-.-.}, at: [<ffffffff8105a729>] try_to_wake_up+0x39/0x2f0 [ 132.978883] #1: (rcu_read_lock){.+.+..}, at: [<ffffffff8105556a>] select_task_rq_fair+0x6a/0xec0 [ 132.978883] [ 132.978883] stack backtrace: [ 132.978883] Pid: 0, comm: swapper Tainted: G W 3.0.0+ #178 [ 132.978883] Call Trace: [ 132.978883] <IRQ> [<ffffffff810a01f6>] lockdep_rcu_suspicious+0xe6/0x100 [ 132.978883] [<ffffffff81055c49>] select_task_rq_fair+0x749/0xec0 [ 132.978883] [<ffffffff8105556a>] ? select_task_rq_fair+0x6a/0xec0 [ 132.978883] [<ffffffff812fe494>] ? do_raw_spin_lock+0x54/0x150 [ 132.978883] [<ffffffff810a1f2d>] ? trace_hardirqs_on+0xd/0x10 [ 132.978883] [<ffffffff8105a7c3>] try_to_wake_up+0xd3/0x2f0 [ 132.978883] [<ffffffff81094f98>] ? ktime_get+0x68/0xf0 [ 132.978883] [<ffffffff8105aa35>] wake_up_process+0x15/0x20 [ 132.978883] [<ffffffff81069dd5>] raise_softirq_irqoff+0x65/0x110 [ 132.978883] [<ffffffff8108eb65>] __hrtimer_start_range_ns+0x415/0x5a0 [ 132.978883] [<ffffffff812fe3ee>] ? do_raw_spin_unlock+0x5e/0xb0 [ 132.978883] [<ffffffff8108ed08>] hrtimer_start+0x18/0x20 [ 132.978883] [<ffffffff8109c9c3>] tick_nohz_stop_sched_tick+0x393/0x450 [ 132.978883] [<ffffffff810694f2>] irq_exit+0xd2/0x100 [ 132.978883] [<ffffffff81829e96>] do_IRQ+0x66/0xe0 [ 132.978883] [<ffffffff81820d53>] common_interrupt+0x13/0x13 [ 132.978883] <EOI> [<ffffffff8103434b>] ? native_safe_halt+0xb/0x10 [ 132.978883] [<ffffffff810a1f2d>] ? trace_hardirqs_on+0xd/0x10 [ 132.978883] [<ffffffff810144ea>] default_idle+0xba/0x370 [ 132.978883] [<ffffffff810147fe>] amd_e400_idle+0x5e/0x130 [ 132.978883] [<ffffffff8100a9f6>] cpu_idle+0xb6/0x120 [ 132.978883] [<ffffffff817f217f>] rest_init+0xef/0x150 [ 132.978883] [<ffffffff817f20e2>] ? rest_init+0x52/0x150 [ 132.978883] [<ffffffff81ed9cf3>] start_kernel+0x3da/0x3e5 [ 132.978883] [<ffffffff81ed9346>] x86_64_start_reservations+0x131/0x135 [ 132.978883] [<ffffffff81ed944d>] x86_64_start_kernel+0x103/0x112 Fix this by calling rcu_idle_enter() after tick_nohz_irq_exit(). Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: NJosh Triplett <josh@joshtriplett.org>
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由 Frederic Weisbecker 提交于
Interrupts notify the idle exit state before calling irq_enter(). But the notifier code calls rcu_read_lock() and this is not allowed while rcu is in an extended quiescent state. We need to wait for irq_enter() -> rcu_idle_exit() to be called before doing so otherwise this results in a grumpy RCU: [ 0.099991] WARNING: at include/linux/rcupdate.h:194 __atomic_notifier_call_chain+0xd2/0x110() [ 0.099991] Hardware name: AMD690VM-FMH [ 0.099991] Modules linked in: [ 0.099991] Pid: 0, comm: swapper Not tainted 3.0.0-rc6+ #255 [ 0.099991] Call Trace: [ 0.099991] <IRQ> [<ffffffff81051c8a>] warn_slowpath_common+0x7a/0xb0 [ 0.099991] [<ffffffff81051cd5>] warn_slowpath_null+0x15/0x20 [ 0.099991] [<ffffffff817d6fa2>] __atomic_notifier_call_chain+0xd2/0x110 [ 0.099991] [<ffffffff817d6ff1>] atomic_notifier_call_chain+0x11/0x20 [ 0.099991] [<ffffffff81001873>] exit_idle+0x43/0x50 [ 0.099991] [<ffffffff81020439>] smp_apic_timer_interrupt+0x39/0xa0 [ 0.099991] [<ffffffff817da253>] apic_timer_interrupt+0x13/0x20 [ 0.099991] <EOI> [<ffffffff8100ae67>] ? default_idle+0xa7/0x350 [ 0.099991] [<ffffffff8100ae65>] ? default_idle+0xa5/0x350 [ 0.099991] [<ffffffff8100b19b>] amd_e400_idle+0x8b/0x110 [ 0.099991] [<ffffffff810cb01f>] ? rcu_enter_nohz+0x8f/0x160 [ 0.099991] [<ffffffff810019a0>] cpu_idle+0xb0/0x110 [ 0.099991] [<ffffffff817a7505>] rest_init+0xe5/0x140 [ 0.099991] [<ffffffff817a7468>] ? rest_init+0x48/0x140 [ 0.099991] [<ffffffff81cc5ca3>] start_kernel+0x3d1/0x3dc [ 0.099991] [<ffffffff81cc5321>] x86_64_start_reservations+0x131/0x135 [ 0.099991] [<ffffffff81cc5412>] x86_64_start_kernel+0xed/0xf4 Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Andy Henroid <andrew.d.henroid@intel.com> Signed-off-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: NJosh Triplett <josh@joshtriplett.org>
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由 Frederic Weisbecker 提交于
The idle notifier, called by enter_idle(), enters into rcu read side critical section but at that time we already switched into the RCU-idle window (rcu_idle_enter() has been called). And it's illegal to use rcu_read_lock() in that state. This results in rcu reporting its bad mood: [ 1.275635] WARNING: at include/linux/rcupdate.h:194 __atomic_notifier_call_chain+0xd2/0x110() [ 1.275635] Hardware name: AMD690VM-FMH [ 1.275635] Modules linked in: [ 1.275635] Pid: 0, comm: swapper Not tainted 3.0.0-rc6+ #252 [ 1.275635] Call Trace: [ 1.275635] [<ffffffff81051c8a>] warn_slowpath_common+0x7a/0xb0 [ 1.275635] [<ffffffff81051cd5>] warn_slowpath_null+0x15/0x20 [ 1.275635] [<ffffffff817d6f22>] __atomic_notifier_call_chain+0xd2/0x110 [ 1.275635] [<ffffffff817d6f71>] atomic_notifier_call_chain+0x11/0x20 [ 1.275635] [<ffffffff810018a0>] enter_idle+0x20/0x30 [ 1.275635] [<ffffffff81001995>] cpu_idle+0xa5/0x110 [ 1.275635] [<ffffffff817a7465>] rest_init+0xe5/0x140 [ 1.275635] [<ffffffff817a73c8>] ? rest_init+0x48/0x140 [ 1.275635] [<ffffffff81cc5ca3>] start_kernel+0x3d1/0x3dc [ 1.275635] [<ffffffff81cc5321>] x86_64_start_reservations+0x131/0x135 [ 1.275635] [<ffffffff81cc5412>] x86_64_start_kernel+0xed/0xf4 [ 1.275635] ---[ end trace a22d306b065d4a66 ]--- Fix this by entering rcu extended quiescent state later, just before the CPU goes to sleep. Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: H. Peter Anvin <hpa@zytor.com> Signed-off-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: NJosh Triplett <josh@joshtriplett.org>
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由 Frederic Weisbecker 提交于
It is assumed that rcu won't be used once we switch to tickless mode and until we restart the tick. However this is not always true, as in x86-64 where we dereference the idle notifiers after the tick is stopped. To prepare for fixing this, add two new APIs: tick_nohz_idle_enter_norcu() and tick_nohz_idle_exit_norcu(). If no use of RCU is made in the idle loop between tick_nohz_enter_idle() and tick_nohz_exit_idle() calls, the arch must instead call the new *_norcu() version such that the arch doesn't need to call rcu_idle_enter() and rcu_idle_exit(). Otherwise the arch must call tick_nohz_enter_idle() and tick_nohz_exit_idle() and also call explicitly: - rcu_idle_enter() after its last use of RCU before the CPU is put to sleep. - rcu_idle_exit() before the first use of RCU after the CPU is woken up. Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com> Cc: Mike Frysinger <vapier@gentoo.org> Cc: Guan Xuetao <gxt@mprc.pku.edu.cn> Cc: David Miller <davem@davemloft.net> Cc: Chris Metcalf <cmetcalf@tilera.com> Cc: Hans-Christian Egtvedt <hans-christian.egtvedt@atmel.com> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Russell King <linux@arm.linux.org.uk> Cc: Paul Mackerras <paulus@samba.org> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Paul Mundt <lethal@linux-sh.org> Signed-off-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com>
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由 Frederic Weisbecker 提交于
The tick_nohz_stop_sched_tick() function, which tries to delay the next timer tick as long as possible, can be called from two places: - From the idle loop to start the dytick idle mode - From interrupt exit if we have interrupted the dyntick idle mode, so that we reprogram the next tick event in case the irq changed some internal state that requires this action. There are only few minor differences between both that are handled by that function, driven by the ts->inidle cpu variable and the inidle parameter. The whole guarantees that we only update the dyntick mode on irq exit if we actually interrupted the dyntick idle mode, and that we enter in RCU extended quiescent state from idle loop entry only. Split this function into: - tick_nohz_idle_enter(), which sets ts->inidle to 1, enters dynticks idle mode unconditionally if it can, and enters into RCU extended quiescent state. - tick_nohz_irq_exit() which only updates the dynticks idle mode when ts->inidle is set (ie: if tick_nohz_idle_enter() has been called). To maintain symmetry, tick_nohz_restart_sched_tick() has been renamed into tick_nohz_idle_exit(). This simplifies the code and micro-optimize the irq exit path (no need for local_irq_save there). This also prepares for the split between dynticks and rcu extended quiescent state logics. We'll need this split to further fix illegal uses of RCU in extended quiescent states in the idle loop. Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com> Cc: Mike Frysinger <vapier@gentoo.org> Cc: Guan Xuetao <gxt@mprc.pku.edu.cn> Cc: David Miller <davem@davemloft.net> Cc: Chris Metcalf <cmetcalf@tilera.com> Cc: Hans-Christian Egtvedt <hans-christian.egtvedt@atmel.com> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Russell King <linux@arm.linux.org.uk> Cc: Paul Mackerras <paulus@samba.org> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Paul Mundt <lethal@linux-sh.org> Signed-off-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: NJosh Triplett <josh@joshtriplett.org>
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由 Paul E. McKenney 提交于
A common debug_lockdep_rcu_enabled() function is used to check whether RCU lockdep splats should be reported, but srcu_read_lock() does not use it. This commit therefore brings srcu_read_lock_held() up to date. Signed-off-by: NPaul E. McKenney <paul.mckenney@linaro.org> Signed-off-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: NJosh Triplett <josh@joshtriplett.org>
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由 Paul E. McKenney 提交于
Catch SRCU up to the other variants of RCU by making PROVE_RCU complain if either srcu_read_lock() or srcu_read_lock_held() are used from within RCU-idle mode. Frederic reworked this to allow for the new versions of his patches that check for extended quiescent states. Signed-off-by: NPaul E. McKenney <paul.mckenney@linaro.org> Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com> Signed-off-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: NJosh Triplett <josh@joshtriplett.org>
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由 Paul E. McKenney 提交于
Simplify things a bit by substituting the definitions of the single-line rcu_read_acquire(), rcu_read_release(), rcu_read_acquire_bh(), rcu_read_release_bh(), rcu_read_acquire_sched(), and rcu_read_release_sched() functions at their call points. Signed-off-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: NJosh Triplett <josh@joshtriplett.org>
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由 Frederic Weisbecker 提交于
We are currently able to detect uses of rcu_dereference_check() inside extended quiescent states (such as the RCU-free window in idle). But rcu_read_lock() and friends can be used without rcu_dereference(), so that the earlier commit checking for use of rcu_dereference() and friends while in RCU idle mode miss some error conditions. This commit therefore adds extended quiescent state checking to rcu_read_lock() and friends. Uses of RCU from within RCU-idle mode are totally ignored by RCU, hence the importance of these checks. Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Lai Jiangshan <laijs@cn.fujitsu.com> Signed-off-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: NJosh Triplett <josh@joshtriplett.org>
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由 Frederic Weisbecker 提交于
Inform the user if an RCU usage error is detected by lockdep while in an extended quiescent state (in this case, the RCU-free window in idle). This is accomplished by adding a line to the RCU lockdep splat indicating whether or not the splat occurred in extended quiescent state. Uses of RCU from within extended quiescent state mode are totally ignored by RCU, hence the importance of this diagnostic. Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Lai Jiangshan <laijs@cn.fujitsu.com> Signed-off-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: NJosh Triplett <josh@joshtriplett.org>
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由 Frederic Weisbecker 提交于
Report that none of the rcu read lock maps are held while in an RCU extended quiescent state (the section between rcu_idle_enter() and rcu_idle_exit()). This helps detect any use of rcu_dereference() and friends from within the section in idle where RCU is not allowed. This way we can guarantee an extended quiescent window where the CPU can be put in dyntick idle mode or can simply aoid to be part of any global grace period completion while in the idle loop. Uses of RCU from such mode are totally ignored by RCU, hence the importance of these checks. Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Lai Jiangshan <laijs@cn.fujitsu.com> Signed-off-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: NJosh Triplett <josh@joshtriplett.org>
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由 Thomas Gleixner 提交于
Empty void functions do not need "return", so this commit removes it from rcu_report_exp_rnp(). Signed-off-by: NThomas Gleixner <tglx@linutronix.de> Signed-off-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com>
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由 Thomas Gleixner 提交于
When setting up an expedited grace period, if there were no readers, the task will awaken itself. This commit removes this useless self-awakening. Signed-off-by: NThomas Gleixner <tglx@linutronix.de> Signed-off-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com>
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由 Paul E. McKenney 提交于
Because rcu_is_cpu_idle() is to be used to check for extended quiescent states in RCU-preempt read-side critical sections, it cannot assume that preemption is disabled. And preemption must be disabled when accessing the dyntick-idle state, because otherwise the following sequence of events could occur: 1. Task A on CPU 1 enters rcu_is_cpu_idle() and picks up the pointer to CPU 1's per-CPU variables. 2. Task B preempts Task A and starts running on CPU 1. 3. Task A migrates to CPU 2. 4. Task B blocks, leaving CPU 1 idle. 5. Task A continues execution on CPU 2, accessing CPU 1's dyntick-idle information using the pointer fetched in step 1 above, and finds that CPU 1 is idle. 6. Task A therefore incorrectly concludes that it is executing in an extended quiescent state, possibly issuing a spurious splat. Therefore, this commit disables preemption within the rcu_is_cpu_idle() function. Signed-off-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: NJosh Triplett <josh@joshtriplett.org>
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由 Paul E. McKenney 提交于
One of lclaudio's systems was seeing RCU CPU stall warnings from idle. These turned out to be caused by a bug that stopped scheduling-clock tick interrupts from being sent to a given CPU for several hundred seconds. This commit therefore updates the documentation to call this out as a possible cause for RCU CPU stall warnings. Signed-off-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: NJosh Triplett <josh@joshtriplett.org>
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由 Paul E. McKenney 提交于
Trace the rcutorture RCU accesses and dump the trace buffer when the first failure is detected. Signed-off-by: NPaul E. McKenney <paul.mckenney@linaro.org> Signed-off-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: NJosh Triplett <josh@joshtriplett.org>
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由 Paul E. McKenney 提交于
Add an EXPORT_SYMBOL_GPL() so that rcutorture can dump the trace buffer upon detection of an RCU error. Signed-off-by: NPaul E. McKenney <paul.mckenney@linaro.org> Signed-off-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: NJosh Triplett <josh@joshtriplett.org>
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由 Paul E. McKenney 提交于
Earlier versions of RCU used the scheduling-clock tick to detect idleness by checking for the idle task, but handled idleness differently for CONFIG_NO_HZ=y. But there are now a number of uses of RCU read-side critical sections in the idle task, for example, for tracing. A more fine-grained detection of idleness is therefore required. This commit presses the old dyntick-idle code into full-time service, so that rcu_idle_enter(), previously known as rcu_enter_nohz(), is always invoked at the beginning of an idle loop iteration. Similarly, rcu_idle_exit(), previously known as rcu_exit_nohz(), is always invoked at the end of an idle-loop iteration. This allows the idle task to use RCU everywhere except between consecutive rcu_idle_enter() and rcu_idle_exit() calls, in turn allowing architecture maintainers to specify exactly where in the idle loop that RCU may be used. Because some of the userspace upcall uses can result in what looks to RCU like half of an interrupt, it is not possible to expect that the irq_enter() and irq_exit() hooks will give exact counts. This patch therefore expands the ->dynticks_nesting counter to 64 bits and uses two separate bitfields to count process/idle transitions and interrupt entry/exit transitions. It is presumed that userspace upcalls do not happen in the idle loop or from usermode execution (though usermode might do a system call that results in an upcall). The counter is hard-reset on each process/idle transition, which avoids the interrupt entry/exit error from accumulating. Overflow is avoided by the 64-bitness of the ->dyntick_nesting counter. This commit also adds warnings if a non-idle task asks RCU to enter idle state (and these checks will need some adjustment before applying Frederic's OS-jitter patches (http://lkml.org/lkml/2011/10/7/246). In addition, validation of ->dynticks and ->dynticks_nesting is added. Signed-off-by: NPaul E. McKenney <paul.mckenney@linaro.org> Signed-off-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: NJosh Triplett <josh@joshtriplett.org>
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由 Paul E. McKenney 提交于
There are a number of bugs that can leak or overuse lock classes, which can cause the maximum number of lock classes (currently 8191) to be exceeded. However, the documentation does not tell you how to track down these problems. This commit addresses this shortcoming. Signed-off-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com>
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由 Paul E. McKenney 提交于
When synchronize_sched_expedited() takes its second and subsequent snapshots of sync_sched_expedited_started, it subtracts 1. This means that the concurrent caller of synchronize_sched_expedited() that incremented to that value sees our successful completion, it will not be able to take advantage of it. This restriction is pointless, given that our full expedited grace period would have happened after the other guy started, and thus should be able to serve as a proxy for the other guy successfully executing try_stop_cpus(). This commit therefore removes the subtraction of 1. Signed-off-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: NJosh Triplett <josh@joshtriplett.org>
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由 Paul E. McKenney 提交于
Because rcu_read_unlock_special() samples rcu_preempted_readers_exp(rnp) after dropping rnp->lock, the following sequence of events is possible: 1. Task A exits its RCU read-side critical section, and removes itself from the ->blkd_tasks list, releases rnp->lock, and is then preempted. Task B remains on the ->blkd_tasks list, and blocks the current expedited grace period. 2. Task B exits from its RCU read-side critical section and removes itself from the ->blkd_tasks list. Because it is the last task blocking the current expedited grace period, it ends that expedited grace period. 3. Task A resumes, and samples rcu_preempted_readers_exp(rnp) which of course indicates that nothing is blocking the nonexistent expedited grace period. Task A is again preempted. 4. Some other CPU starts an expedited grace period. There are several tasks blocking this expedited grace period queued on the same rcu_node structure that Task A was using in step 1 above. 5. Task A examines its state and incorrectly concludes that it was the last task blocking the expedited grace period on the current rcu_node structure. It therefore reports completion up the rcu_node tree. 6. The expedited grace period can then incorrectly complete before the tasks blocked on this same rcu_node structure exit their RCU read-side critical sections. Arbitrarily bad things happen. This commit therefore takes a snapshot of rcu_preempted_readers_exp(rnp) prior to dropping the lock, so that only the last task thinks that it is the last task, thus avoiding the failure scenario laid out above. Signed-off-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: NJosh Triplett <josh@joshtriplett.org>
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由 Paul E. McKenney 提交于
The ->signaled field was named before complications in the form of dyntick-idle mode and offlined CPUs. These complications have required that force_quiescent_state() be implemented as a state machine, instead of simply unconditionally sending reschedule IPIs. Therefore, this commit renames ->signaled to ->fqs_state to catch up with the new force_quiescent_state() reality. Signed-off-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: NJosh Triplett <josh@joshtriplett.org>
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- 10 12月, 2011 9 次提交
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由 Linus Torvalds 提交于
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git://git.samba.org/sfrench/cifs-2.6由 Linus Torvalds 提交于
* git://git.samba.org/sfrench/cifs-2.6: cifs: check for NULL last_entry before calling cifs_save_resume_key cifs: attempt to freeze while looping on a receive attempt cifs: Fix sparse warning when calling cifs_strtoUCS CIFS: Add descriptions to the brlock cache functions
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip由 Linus Torvalds 提交于
* 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86, efi: Calling __pa() with an ioremap()ed address is invalid x86, hpet: Immediately disable HPET timer 1 if rtc irq is masked x86/intel_mid: Kconfig select fix x86/intel_mid: Fix the Kconfig for MID selection
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git://git.pengutronix.de/git/wsa/linux-2.6由 Linus Torvalds 提交于
* 'spi/for-3.2' of git://git.pengutronix.de/git/wsa/linux-2.6: spi/gpio: fix section mismatch warning spi/fsl-espi: disable CONFIG_SPI_FSL_ESPI=m build spi/nuc900: Include linux/module.h spi/ath79: fix compile error due to missing include
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git://neil.brown.name/md由 Linus Torvalds 提交于
* 'for-linus' of git://neil.brown.name/md: md: raid5 crash during degradation md/raid5: never wait for bad-block acks on failed device. md: ensure new badblocks are handled promptly. md: bad blocks shouldn't cause a Blocked status on a Faulty device. md: take a reference to mddev during sysfs access. md: refine interpretation of "hold_active == UNTIL_IOCTL". md/lock: ensure updates to page_attrs are properly locked.
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git://git.kernel.org/pub/scm/linux/kernel/git/cmetcalf/linux-tile由 Linus Torvalds 提交于
* git://git.kernel.org/pub/scm/linux/kernel/git/cmetcalf/linux-tile: arch/tile: use new generic {enable,disable}_percpu_irq() routines drivers/net/ethernet/tile: use skb_frag_page() API asm-generic/unistd.h: support new process_vm_{readv,write} syscalls arch/tile: fix double-free bug in homecache_free_pages() arch/tile: add a few #includes and an EXPORT to catch up with kernel changes.
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git://git.kernel.org/pub/scm/linux/kernel/git/joro/iommu由 Linus Torvalds 提交于
* 'iommu/fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/joro/iommu: MAINTAINERS: Update amd-iommu F: patterns iommu/amd: Fix typo in kernel-parameters.txt iommu/msm: Fix compile error in mach-msm/devices-iommu.c Fix comparison using wrong pointer variable in dma debug code
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git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound由 Linus Torvalds 提交于
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound: ALSA: hda/realtek - Fix lost speaker volume controls ALSA: hda/realtek - Create "Bass Speaker" for two speaker pins ALSA: hda/realtek - Don't create extra controls with channel suffix ALSA: hda - Fix remaining VREF mute-LED NID check in post-3.1 changes ALSA: hda - Fix GPIO LED setup for IDT 92HD75 codecs ASoC: Provide a more complete DMA driver stub ASoC: Remove references to corgi and spitz from machine driver document ASoC: Make SND_SOC_MX27VIS_AIC32X4 depend on I2C ASoC: Fix dependency for SND_SOC_RAUMFELD and SND_PXA2XX_SOC_HX4700 ASoC: uda1380: Return proper error in uda1380_modinit failure path ASoC: kirkwood: Make SND_KIRKWOOD_SOC_OPENRD and SND_KIRKWOOD_SOC_T5325 depend on I2C ASoC: Mark WM8994 ADC muxes as virtual ALSA: hda/realtek - Fix Oops in alc_mux_select() ALSA: sis7019 - give slow codecs more time to reset
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip由 Linus Torvalds 提交于
* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: perf: Do no try to schedule task events if there are none lockdep, kmemcheck: Annotate ->lock in lockdep_init_map() perf header: Use event_name() to get an event name perf stat: Failure with "Operation not supported"
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- 09 12月, 2011 3 次提交
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由 Mandeep Singh Baines 提交于
In order to safely dereference current->real_parent inside an rcu_read_lock, we need an rcu_dereference. Signed-off-by: NMandeep Singh Baines <msb@chromium.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Pavel Emelyanov <xemul@openvz.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Kees Cook <keescook@chromium.org> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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由 Alexandre Bounine 提交于
Modify initialization of PCIe capability registers in Tsi721 mport driver: - change Completion Timeout value to avoid unexpected data transfer aborts during intensive traffic. - replace hardcoded offset of PCIe capability block by making it use the common function. This patch is applicable to kernel versions starting from 3.2-rc1. Signed-off-by: NAlexandre Bounine <alexandre.bounine@idt.com> Cc: Matt Porter <mporter@kernel.crashing.org> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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由 Alexandre Bounine 提交于
Bug fix for Tsi721 RapidIO mport driver: Tsi721 supports four RapidIO mailboxes (MBOX0 - MBOX3) as defined by RapidIO specification. Mailbox resources has to be properly reported to allow use of all available mailboxes (initial version reports only MBOX0). This patch is applicable to kernel versions staring from 3.2-rc1. Signed-off-by: NAlexandre Bounine <alexandre.bounine@idt.com> Cc: Matt Porter <mporter@kernel.crashing.org> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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