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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: 29d7bbada9
("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>
This commit is contained in:
parent
7089db84e3
commit
202461e2f3
@ -347,17 +347,16 @@ static void tick_handle_periodic_broadcast(struct clock_event_device *dev)
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*
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* Called when the system enters a state where affected tick devices
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* might stop. Note: TICK_BROADCAST_FORCE cannot be undone.
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*
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* Called with interrupts disabled, so clockevents_lock is not
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* required here because the local clock event device cannot go away
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* under us.
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*/
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void tick_broadcast_control(enum tick_broadcast_mode mode)
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{
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struct clock_event_device *bc, *dev;
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struct tick_device *td;
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int cpu, bc_stopped;
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unsigned long flags;
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/* Protects also the local clockevent device. */
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raw_spin_lock_irqsave(&tick_broadcast_lock, flags);
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td = this_cpu_ptr(&tick_cpu_device);
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dev = td->evtdev;
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@ -365,12 +364,11 @@ void tick_broadcast_control(enum tick_broadcast_mode mode)
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* Is the device not affected by the powerstate ?
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*/
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if (!dev || !(dev->features & CLOCK_EVT_FEAT_C3STOP))
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return;
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goto out;
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if (!tick_device_is_functional(dev))
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return;
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goto out;
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raw_spin_lock(&tick_broadcast_lock);
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cpu = smp_processor_id();
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bc = tick_broadcast_device.evtdev;
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bc_stopped = cpumask_empty(tick_broadcast_mask);
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@ -420,7 +418,8 @@ void tick_broadcast_control(enum tick_broadcast_mode mode)
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tick_broadcast_setup_oneshot(bc);
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}
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}
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raw_spin_unlock(&tick_broadcast_lock);
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out:
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raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
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}
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EXPORT_SYMBOL_GPL(tick_broadcast_control);
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