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authorThomas Gleixner2014-10-02 17:32:16 +0200
committerFelipe Balbi2014-10-23 09:55:41 -0500
commitd2e6d62c9cbbc2da4211f672dbeea08960e29a80 (patch)
tree724b0e87ad929226f68b52caeea6442c2d657f59 /drivers/usb
parent36f84ffb45c75ff10442a9f8f2fd91dcf6c6f5dd (diff)
usb: musb: cppi41: restart hrtimer only if not yet done
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. Cc: stable@vger.kernel.org Reported-by: Torben Hohn <torbenh@linutronix.de> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> [bigeasy: collected information and created a patch + description based on it] Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Felipe Balbi <balbi@ti.com>
Diffstat (limited to 'drivers/usb')
-rw-r--r--drivers/usb/musb/musb_cppi41.c3
1 files changed, 2 insertions, 1 deletions
diff --git a/drivers/usb/musb/musb_cppi41.c b/drivers/usb/musb/musb_cppi41.c
index acdfb3e68a90..5a9b977fbc19 100644
--- a/drivers/usb/musb/musb_cppi41.c
+++ b/drivers/usb/musb/musb_cppi41.c
@@ -209,7 +209,8 @@ static enum hrtimer_restart cppi41_recheck_tx_req(struct hrtimer *timer)
}
}
- 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, 20 * NSEC_PER_USEC));