1. 25 10月, 2016 12 次提交
    • P
      locking/mutex: Restructure wait loop · 5bbd7e64
      Peter Zijlstra 提交于
      Doesn't really matter yet, but pull the HANDOFF and trylock out from
      under the wait_lock.
      
      The intention is to add an optimistic spin loop here, which requires
      we do not hold the wait_lock, so shuffle code around in preparation.
      
      Also clarify the purpose of taking the wait_lock in the wait loop, its
      tempting to want to avoid it altogether, but the cancellation cases
      need to to avoid losing wakeups.
      Suggested-by: NWaiman Long <waiman.long@hpe.com>
      Tested-by: NJason Low <jason.low2@hpe.com>
      Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
      Cc: Andrew Morton <akpm@linux-foundation.org>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: linux-kernel@vger.kernel.org
      Signed-off-by: NIngo Molnar <mingo@kernel.org>
      5bbd7e64
    • P
      locking/mutex: Add lock handoff to avoid starvation · 9d659ae1
      Peter Zijlstra 提交于
      Implement lock handoff to avoid lock starvation.
      
      Lock starvation is possible because mutex_lock() allows lock stealing,
      where a running (or optimistic spinning) task beats the woken waiter
      to the acquire.
      
      Lock stealing is an important performance optimization because waiting
      for a waiter to wake up and get runtime can take a significant time,
      during which everyboy would stall on the lock.
      
      The down-side is of course that it allows for starvation.
      
      This patch has the waiter requesting a handoff if it fails to acquire
      the lock upon waking. This re-introduces some of the wait time,
      because once we do a handoff we have to wait for the waiter to wake up
      again.
      
      A future patch will add a round of optimistic spinning to attempt to
      alleviate this penalty, but if that turns out to not be enough, we can
      add a counter and only request handoff after multiple failed wakeups.
      
      There are a few tricky implementation details:
      
       - accepting a handoff must only be done in the wait-loop. Since the
         handoff condition is owner == current, it can easily cause
         recursive locking trouble.
      
       - accepting the handoff must be careful to provide the ACQUIRE
         semantics.
      
       - having the HANDOFF bit set on unlock requires care, we must not
         clear the owner.
      
       - we must be careful to not leave HANDOFF set after we've acquired
         the lock. The tricky scenario is setting the HANDOFF bit on an
         unlocked mutex.
      Tested-by: NJason Low <jason.low2@hpe.com>
      Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
      Reviewed-by: NWaiman Long <Waiman.Long@hpe.com>
      Cc: Andrew Morton <akpm@linux-foundation.org>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: linux-kernel@vger.kernel.org
      Signed-off-by: NIngo Molnar <mingo@kernel.org>
      9d659ae1
    • P
      locking/mutex: Allow MUTEX_SPIN_ON_OWNER when DEBUG_MUTEXES · a3ea3d9b
      Peter Zijlstra 提交于
      Now that mutex::count and mutex::owner are the same field, we can
      allow SPIN_ON_OWNER while DEBUG_MUTEX.
      Tested-by: NJason Low <jason.low2@hpe.com>
      Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
      Cc: Andrew Morton <akpm@linux-foundation.org>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: linux-kernel@vger.kernel.org
      Signed-off-by: NIngo Molnar <mingo@kernel.org>
      a3ea3d9b
    • P
      locking/mutex: Kill arch specific code · 890658b7
      Peter Zijlstra 提交于
      Its all generic atomic_long_t stuff now.
      Tested-by: NJason Low <jason.low2@hpe.com>
      Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
      Cc: Andrew Morton <akpm@linux-foundation.org>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: linux-arch@vger.kernel.org
      Cc: linux-kernel@vger.kernel.org
      Signed-off-by: NIngo Molnar <mingo@kernel.org>
      890658b7
    • P
      locking/mutex: Rework mutex::owner · 3ca0ff57
      Peter Zijlstra 提交于
      The current mutex implementation has an atomic lock word and a
      non-atomic owner field.
      
      This disparity leads to a number of issues with the current mutex code
      as it means that we can have a locked mutex without an explicit owner
      (because the owner field has not been set, or already cleared).
      
      This leads to a number of weird corner cases, esp. between the
      optimistic spinning and debug code. Where the optimistic spinning
      code needs the owner field updated inside the lock region, the debug
      code is more relaxed because the whole lock is serialized by the
      wait_lock.
      
      Also, the spinning code itself has a few corner cases where we need to
      deal with a held lock without an owner field.
      
      Furthermore, it becomes even more of a problem when trying to fix
      starvation cases in the current code. We end up stacking special case
      on special case.
      
      To solve this rework the basic mutex implementation to be a single
      atomic word that contains the owner and uses the low bits for extra
      state.
      
      This matches how PI futexes and rt_mutex already work. By having the
      owner an integral part of the lock state a lot of the problems
      dissapear and we get a better option to deal with starvation cases,
      direct owner handoff.
      
      Changing the basic mutex does however invalidate all the arch specific
      mutex code; this patch leaves that unused in-place, a later patch will
      remove that.
      Tested-by: NJason Low <jason.low2@hpe.com>
      Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
      Reviewed-by: NWill Deacon <will.deacon@arm.com>
      Cc: Andrew Morton <akpm@linux-foundation.org>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: linux-kernel@vger.kernel.org
      Signed-off-by: NIngo Molnar <mingo@kernel.org>
      3ca0ff57
    • P
      locking/drm: Kill mutex trickery · 3ab7c086
      Peter Zijlstra 提交于
      Poking at lock internals is not cool. Since I'm going to change the
      implementation this will break, take it out.
      Tested-by: NJason Low <jason.low2@hpe.com>
      Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
      Cc: Andrew Morton <akpm@linux-foundation.org>
      Cc: Chris Wilson <chris@chris-wilson.co.uk>
      Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
      Cc: Linus Torvalds <torvalds@linux-foundation.org>
      Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Rob Clark <robdclark@gmail.com>
      Cc: Thomas Gleixner <tglx@linutronix.de>
      Cc: linux-kernel@vger.kernel.org
      Signed-off-by: NIngo Molnar <mingo@kernel.org>
      3ab7c086
    • L
      Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6 · 9fe68cad
      Linus Torvalds 提交于
      Pull crypto fix from Herbert Xu:
       "This fixes a regression caused by the stack vmalloc change"
      
      * 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6:
        hwrng: core - Don't use a stack buffer in add_early_randomness()
      9fe68cad
    • L
      Merge tag 'clk-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/clk/linux · b5cd8917
      Linus Torvalds 提交于
      Pull clk fixes from Stephen Boyd:
       "This is the first batch of clk driver fixes for this release.
      
        We have a handful of fixes for the uniphier clk driver that was
        introduced recently, as well as Kconfig option hiding, module
        autoloading markings, and a few fixes for clk_hw based registration
        patches that went in this merge window"
      
      * tag 'clk-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/clk/linux:
        clk: at91: Fix a return value in case of error
        clk: uniphier: rename MIO clock to SD clock for Pro5, PXs2, LD20 SoCs
        clk: uniphier: fix memory overrun bug
        clk: hi6220: use CLK_OF_DECLARE_DRIVER for sysctrl and mediactrl clock init
        clk: mvebu: armada-37xx-periph: Fix the clock gate flag
        clk: bcm2835: Clamp the PLL's requested rate to the hardware limits.
        clk: max77686: fix number of clocks setup for clk_hw based registration
        clk: mvebu: armada-37xx-periph: Fix the clock provider registration
        clk: core: add __init decoration for CLK_OF_DECLARE_DRIVER function
        clk: mediatek: Add hardware dependency
        clk: samsung: clk-exynos-audss: Fix module autoload
        clk: uniphier: fix type of variable passed to regmap_read()
        clk: uniphier: add system clock support for sLD3 SoC
      b5cd8917
    • L
      Merge tag 'gpio-v4.9-2' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-gpio · 1ce5bdb8
      Linus Torvalds 提交于
      Pull GPIO fixes from Linus Walleij:
       "Here is a set of GPIO fixes for the v4.9 kernel series:
      
         - Fix up off-by one and line offset validation, info leak to
           userspace, and reject invalid flags. Those are especially valuable
           hardening patches from Lars-Peter Clausen, all tagged for stable.
      
         - Fix module autoload for TS4800 and ATH79.
      
         - Correct the IRQ handler for MPC8xxx to use handle_level_irq() as it
           (a) reacts to edges not levels and (b) even implements .irq_ack().
           We were missing IRQs here.
      
         - Fix the error path for acpi_dev_gpio_irq_get()
      
         - Fix a memory leak in the MXS driver.
      
         - Fix an annoying typo in the STMPE driver.
      
         - Put a dependency on sysfs to the mockup driver"
      
      * tag 'gpio-v4.9-2' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-gpio:
        gpio: mpc8xxx: Correct irq handler function
        gpio: ath79: Fix module autoload
        gpio: ts4800: Fix module autoload
        gpio: GPIO_GET_LINEEVENT_IOCTL: Reject invalid line and event flags
        gpio: GPIO_GET_LINEHANDLE_IOCTL: Reject invalid line flags
        gpio: GPIOHANDLE_GET_LINE_VALUES_IOCTL: Fix information leak
        gpio: GPIO_GET_LINEEVENT_IOCTL: Validate line offset
        gpio: GPIOHANDLE_GET_LINE_VALUES_IOCTL: Fix information leak
        gpio: GPIO_GET_LINEHANDLE_IOCTL: Validate line offset
        gpio: GPIO_GET_CHIPINFO_IOCTL: Fix information leak
        gpio: GPIO_GET_CHIPINFO_IOCTL: Fix line offset validation
        gpio / ACPI: fix returned error from acpi_dev_gpio_irq_get()
        gpio: mockup: add sysfs dependency
        gpio: stmpe: || vs && typo
        gpio: mxs: Unmap region obtained by of_iomap
        gpio/board.txt: point to gpiod_set_value
      1ce5bdb8
    • L
      Merge tag 'for-linus-4.9-rc2-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip · aa34e07e
      Linus Torvalds 提交于
      Pull xen fixes from David Vrabel:
      
       - advertise control feature flags in xenstore
      
       - fix x86 build when XEN_PVHVM is disabled
      
      * tag 'for-linus-4.9-rc2-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip:
        xenbus: check return value of xenbus_scanf()
        xenbus: prefer list_for_each()
        x86: xen: move cpu_up functions out of ifdef
        xenbus: advertise control feature flags
      aa34e07e
    • L
      mm: unexport __get_user_pages() · 0d731759
      Lorenzo Stoakes 提交于
      This patch unexports the low-level __get_user_pages() function.
      
      Recent refactoring of the get_user_pages* functions allow flags to be
      passed through get_user_pages() which eliminates the need for access to
      this function from its one user, kvm.
      
      We can see that the two calls to get_user_pages() which replace
      __get_user_pages() in kvm_main.c are equivalent by examining their call
      stacks:
      
        get_user_page_nowait():
          get_user_pages(start, 1, flags, page, NULL)
          __get_user_pages_locked(current, current->mm, start, 1, page, NULL, NULL,
      			    false, flags | FOLL_TOUCH)
          __get_user_pages(current, current->mm, start, 1,
      		     flags | FOLL_TOUCH | FOLL_GET, page, NULL, NULL)
      
        check_user_page_hwpoison():
          get_user_pages(addr, 1, flags, NULL, NULL)
          __get_user_pages_locked(current, current->mm, addr, 1, NULL, NULL, NULL,
      			    false, flags | FOLL_TOUCH)
          __get_user_pages(current, current->mm, addr, 1, flags | FOLL_TOUCH, NULL,
      		     NULL, NULL)
      Signed-off-by: NLorenzo Stoakes <lstoakes@gmail.com>
      Acked-by: NPaolo Bonzini <pbonzini@redhat.com>
      Acked-by: NMichal Hocko <mhocko@suse.com>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      0d731759
    • L
      proc: don't use FOLL_FORCE for reading cmdline and environment · 272ddc8b
      Linus Torvalds 提交于
      Now that Lorenzo cleaned things up and made the FOLL_FORCE users
      explicit, it becomes obvious how some of them don't really need
      FOLL_FORCE at all.
      
      So remove FOLL_FORCE from the proc code that reads the command line and
      arguments from user space.
      
      The mem_rw() function actually does want FOLL_FORCE, because gdd (and
      possibly many other debuggers) use it as a much more convenient version
      of PTRACE_PEEKDATA, but we should consider making the FOLL_FORCE part
      conditional on actually being a ptracer.  This does not actually do
      that, just moves adds a comment to that effect and moves the gup_flags
      settings next to each other.
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      272ddc8b
  2. 24 10月, 2016 12 次提交
  3. 23 10月, 2016 5 次提交
  4. 22 10月, 2016 11 次提交