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author | Mike Galbraith <efault@gmx.de> | 2017-02-13 03:31:55 +0100 |
---|---|---|
committer | Thomas Gleixner <tglx@linutronix.de> | 2017-02-13 09:49:31 +0100 |
commit | 202461e2f3c15dbfb05825d29ace0d20cdf55fa4 (patch) | |
tree | 133b42876fb28c1bd8634c6c03d276b53fb10a8c /kernel | |
parent | 7089db84e356562f8ba737c29e472cc42d530dbc (diff) | |
download | linux-stable-202461e2f3c15dbfb05825d29ace0d20cdf55fa4.tar.gz linux-stable-202461e2f3c15dbfb05825d29ace0d20cdf55fa4.tar.bz2 linux-stable-202461e2f3c15dbfb05825d29ace0d20cdf55fa4.zip |
tick/broadcast: Prevent deadlock on tick_broadcast_lock
tick_broadcast_lock is taken from interrupt context, but the following call
chain takes the lock without disabling interrupts:
[ 12.703736] _raw_spin_lock+0x3b/0x50
[ 12.703738] tick_broadcast_control+0x5a/0x1a0
[ 12.703742] intel_idle_cpu_online+0x22/0x100
[ 12.703744] cpuhp_invoke_callback+0x245/0x9d0
[ 12.703752] cpuhp_thread_fun+0x52/0x110
[ 12.703754] smpboot_thread_fn+0x276/0x320
So the following deadlock can happen:
lock(tick_broadcast_lock);
<Interrupt>
lock(tick_broadcast_lock);
intel_idle_cpu_online() is the only place which violates the calling
convention of tick_broadcast_control(). This was caused by the removal of
the smp function call in course of the cpu hotplug rework.
Instead of slapping local_irq_disable/enable() at the call site, we can
relax the calling convention and handle it in the core code, which makes
the whole machinery more robust.
Fixes: 29d7bbada98e ("intel_idle: Remove superfluous SMP fuction call")
Reported-by: Gabriel C <nix.or.die@gmail.com>
Signed-off-by: Mike Galbraith <efault@gmx.de>
Cc: Ruslan Ruslichenko <rruslich@cisco.com>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: Greg KH <gregkh@linuxfoundation.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: lwn@lwn.net
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Anna-Maria Gleixner <anna-maria@linutronix.de>
Cc: Sebastian Siewior <bigeasy@linutronix.de>
Cc: stable <stable@vger.kernel.org>
Link: http://lkml.kernel.org/r/1486953115.5912.4.camel@gmx.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'kernel')
-rw-r--r-- | kernel/time/tick-broadcast.c | 15 |
1 files changed, 7 insertions, 8 deletions
diff --git a/kernel/time/tick-broadcast.c b/kernel/time/tick-broadcast.c index 3109204c87cc..17ac99b60ee5 100644 --- a/kernel/time/tick-broadcast.c +++ b/kernel/time/tick-broadcast.c @@ -347,17 +347,16 @@ static void tick_handle_periodic_broadcast(struct clock_event_device *dev) * * Called when the system enters a state where affected tick devices * might stop. Note: TICK_BROADCAST_FORCE cannot be undone. - * - * Called with interrupts disabled, so clockevents_lock is not - * required here because the local clock event device cannot go away - * under us. */ void tick_broadcast_control(enum tick_broadcast_mode mode) { struct clock_event_device *bc, *dev; struct tick_device *td; int cpu, bc_stopped; + unsigned long flags; + /* Protects also the local clockevent device. */ + raw_spin_lock_irqsave(&tick_broadcast_lock, flags); td = this_cpu_ptr(&tick_cpu_device); dev = td->evtdev; @@ -365,12 +364,11 @@ void tick_broadcast_control(enum tick_broadcast_mode mode) * Is the device not affected by the powerstate ? */ if (!dev || !(dev->features & CLOCK_EVT_FEAT_C3STOP)) - return; + goto out; if (!tick_device_is_functional(dev)) - return; + goto out; - raw_spin_lock(&tick_broadcast_lock); cpu = smp_processor_id(); bc = tick_broadcast_device.evtdev; bc_stopped = cpumask_empty(tick_broadcast_mask); @@ -420,7 +418,8 @@ void tick_broadcast_control(enum tick_broadcast_mode mode) tick_broadcast_setup_oneshot(bc); } } - raw_spin_unlock(&tick_broadcast_lock); +out: + raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags); } EXPORT_SYMBOL_GPL(tick_broadcast_control); |