This is a note to let you know that I've just added the patch titled
usb: musb: cppi41: restart hrtimer only if not yet done
to the 3.14-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
usb-musb-cppi41-restart-hrtimer-only-if-not-yet-done.patch
and it can be found in the queue-3.14 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From d2e6d62c9cbbc2da4211f672dbeea08960e29a80 Mon Sep 17 00:00:00 2001
From: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Date: Thu, 2 Oct 2014 17:32:16 +0200
Subject: usb: musb: cppi41: restart hrtimer only if not yet done
From: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
commit d2e6d62c9cbbc2da4211f672dbeea08960e29a80 upstream.
commit c58d80f52 ("usb: musb: Ensure that cppi41 timer gets armed on
premature DMA TX irq") fixed hrtimer scheduling bug. There is one left
which does not trigger that often.
The following scenario is still possible:
lock(&x->lock);
hrtimer_start(&x->t);
unlock(&x->lock);
expires:
t->function();
lock(&x->lock);
lock(&x->lock); if (!hrtimer_queued(&x->t))
hrtimer_start(&x->t);
unlock(&x->lock);
if (!list_empty(x->early_tx_list))
ret = HRTIMER_RESTART;
-> hrtimer_forward_now(...)
} else
ret = HRTIMER_NORESTART;
unlock(&x->lock);
and the timer callback returns HRTIMER_RESTART for an armed timer. This
is wrong and we run into the BUG_ON() in __run_hrtimer().
This can happens on SMP or PREEMPT-RT.
The patch fixes the problem by only starting the timer if the timer is
not yet queued.
Reported-by: Torben Hohn <torbenh@xxxxxxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
[bigeasy: collected information and created a patch + description based
on it]
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
Signed-off-by: Felipe Balbi <balbi@xxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/usb/musb/musb_cppi41.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
--- a/drivers/usb/musb/musb_cppi41.c
+++ b/drivers/usb/musb/musb_cppi41.c
@@ -190,7 +190,8 @@ static enum hrtimer_restart cppi41_reche
}
}
- if (!list_empty(&controller->early_tx_list)) {
+ if (!list_empty(&controller->early_tx_list) &&
+ !hrtimer_is_queued(&controller->early_tx)) {
ret = HRTIMER_RESTART;
hrtimer_forward_now(&controller->early_tx,
ktime_set(0, 150 * NSEC_PER_USEC));
Patches currently in stable-queue which might be from tglx@xxxxxxxxxxxxx are
queue-3.14/usb-musb-cppi41-restart-hrtimer-only-if-not-yet-done.patch
queue-3.14/x86-reject-x32-executables-if-x32-abi-not-supported.patch
queue-3.14/x86-pageattr-prevent-overflow-in-slow_virt_to_phys-for-x86_pae.patch
queue-3.14/x86-add-cpu_detect_cache_sizes-to-init_intel-add-quark-legacy_cache.patch
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