Pull scheduler fix from Thomas Gleixner: "Fix a long standing state race in finish_task_switch()" * 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: sched/core: Fix TASK_DEAD race in finish_task_switch()
A recent cleanup removed the 'irq' parameter from many functions, but
left the documentation for this in place for at least one function.
This removes it.
Fixes: bd0b9ac405e1 ("genirq: Remove irq argument from irq flow handlers")
Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: Grygorii Strashko <grygorii.strashko@ti.com>
Cc: Tony Lindgren <tony@atomide.com>
Cc: Linus Walleij <linus.walleij@linaro.org>
Cc: kbuild-all@01.org
Cc: Austin Schuh <austin@peloton-tech.com>
Cc: Santosh Shilimkar <ssantosh@kernel.org>
Cc: linux-arm-kernel@lists.infradead.org
Link: http://lkml.kernel.org/r/5400000.cD19rmgWjV@wuerfel
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
A cleanup of the omap gpio driver introduced a use of the handle_bad_irq() function in a device driver that can be a loadable module. This broke the ARM allmodconfig build: ERROR: "handle_bad_irq" [drivers/gpio/gpio-omap.ko] undefined! This patch exports the handle_bad_irq symbol in order to allow the use in modules. Signed-off-by: Arnd Bergmann <arnd@arndb.de> Cc: Grygorii Strashko <grygorii.strashko@ti.com> Cc: Santosh Shilimkar <ssantosh@kernel.org> Cc: Linus Walleij <linus.walleij@linaro.org> Cc: Austin Schuh <austin@peloton-tech.com> Cc: Tony Lindgren <tony@atomide.com> Cc: linux-arm-kernel@lists.infradead.org Link: http://lkml.kernel.org/r/5847725.4IBopItaOr@wuerfel Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
So the problem this patch is trying to address is as follows:
CPU0 CPU1
context_switch(A, B)
ttwu(A)
LOCK A->pi_lock
A->on_cpu == 0
finish_task_switch(A)
prev_state = A->state <-.
WMB |
A->on_cpu = 0; |
UNLOCK rq0->lock |
| context_switch(C, A)
`-- A->state = TASK_DEAD
prev_state == TASK_DEAD
put_task_struct(A)
context_switch(A, C)
finish_task_switch(A)
A->state == TASK_DEAD
put_task_struct(A)
The argument being that the WMB will allow the load of A->state on CPU0
to cross over and observe CPU1's store of A->state, which will then
result in a double-drop and use-after-free.
Now the comment states (and this was true once upon a long time ago)
that we need to observe A->state while holding rq->lock because that
will order us against the wakeup; however the wakeup will not in fact
acquire (that) rq->lock; it takes A->pi_lock these days.
We can obviously fix this by upgrading the WMB to an MB, but that is
expensive, so we'd rather avoid that.
The alternative this patch takes is: smp_store_release(&A->on_cpu, 0),
which avoids the MB on some archs, but not important ones like ARM.
Reported-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: <stable@vger.kernel.org> # v3.1+
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Cc: manfred@colorfullife.com
Cc: will.deacon@arm.com
Fixes: e4a52bcb9a18 ("sched: Remove rq->lock from the first half of ttwu()")
Link: http://lkml.kernel.org/r/20150929124509.GG3816@twins.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Pull irq fixes from Thomas Gleixner:
"This update contains:
- Fix for a long standing race affecting /proc/irq/NNN
- One line fix for ARM GICV3-ITS counting the wrong data
- Warning silencing in ARM GICV3-ITS. Another GCC trying to be
overly clever issue"
* 'irq-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
irqchip/gic-v3-its: Count additional LPIs for the aliased devices
irqchip/gic-v3-its: Silence warning when its_lpi_alloc_chunks gets inlined
genirq: Fix race in register_irq_proc()
Pull timer fixes from Ingo Molnar: "An abs64() fix in the watchdog driver, and two clocksource driver NO_IRQ assumption fixes" * 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: clocksource: Fix abs() usage w/ 64bit values clocksource/drivers/keystone: Fix bad NO_IRQ usage clocksource/drivers/rockchip: Fix bad NO_IRQ usage
This patch fixes one cases where abs() was being used with 64-bit nanosecond values, where the result may be capped at 32-bits. This potentially could cause watchdog false negatives on 32-bit systems, so this patch addresses the issue by using abs64(). Signed-off-by: John Stultz <john.stultz@linaro.org> Cc: Prarit Bhargava <prarit@redhat.com> Cc: Richard Cochran <richardcochran@gmail.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: stable@vger.kernel.org Link: http://lkml.kernel.org/r/1442279124-7309-2-git-send-email-john.stultz@linaro.org Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Per-IRQ directories in procfs are created only when a handler is first added to the irqdesc, not when the irqdesc is created. In the case of a shared IRQ, multiple tasks can race to create a directory. This race condition seems to have been present forever, but is easier to hit with async probing. Signed-off-by: Ben Hutchings <ben@decadent.org.uk> Link: http://lkml.kernel.org/r/1443266636.2004.2.camel@decadent.org.uk Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: stable@vger.kernel.org
Pull RCU fixes from Ingo Molnar: "Two RCU fixes: - work around bug with recent GCC versions. - fix false positive lockdep splat" * 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: rcu: Suppress lockdep false positive for rcp->exp_funnel_mutex rcu: Change _wait_rcu_gp() to work around GCC bug 67055
Pull RCU fixes from Paul E. McKenney, for two regressions introduced in this merge window: - Fix bug with recent GCCs. - Fix false positive lockdep splat. Signed-off-by: Ingo Molnar <mingo@kernel.org>