| Message ID | 1415237332-26971-1-git-send-email-kamal@canonical.com |
|---|---|
| State | New |
| Headers | show |
diff --git a/drivers/usb/musb/musb_cppi41.c b/drivers/usb/musb/musb_cppi41.c index 4a5af5c..3faaeb7 100644 --- a/drivers/usb/musb/musb_cppi41.c +++ b/drivers/usb/musb/musb_cppi41.c @@ -190,7 +190,8 @@ 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, 150 * NSEC_PER_USEC));
This is a note to let you know that I have just added a patch titled usb: musb: cppi41: restart hrtimer only if not yet done to the linux-3.13.y-queue branch of the 3.13.y.z extended stable tree which can be found at: http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.13.y-queue This patch is scheduled to be released in version 3.13.11.11. If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 3.13.y.z tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Kamal ------ From 00776ef5efc22ec28e03dae2b82d2173505a63e1 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner <tglx@linutronix.de> Date: Thu, 2 Oct 2014 17:32:16 +0200 Subject: usb: musb: cppi41: restart hrtimer only if not yet done 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@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> Signed-off-by: Kamal Mostafa <kamal@canonical.com> --- drivers/usb/musb/musb_cppi41.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) -- 1.9.1