diff options
| author | Peter Zijlstra <peterz@infradead.org> | 2021-06-11 11:28:11 +0300 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2021-06-18 12:43:06 +0300 |
| commit | 37aadc687ab441bbcb693ddae613acf9afcea1ab (patch) | |
| tree | 83a8142d60076d6742205e513fc0fac6c0435fa5 /drivers/usb/gadget | |
| parent | b2c0931a07b7376c6291e0cfb347ad27f7b66263 (diff) | |
| download | linux-37aadc687ab441bbcb693ddae613acf9afcea1ab.tar.xz | |
sched: Unbreak wakeups
Remove broken task->state references and let wake_up_process() DTRT.
The anti-pattern in these patches breaks the ordering of ->state vs
COND as described in the comment near set_current_state() and can lead
to missed wakeups:
(OoO load, observes RUNNING)<-.
for (;;) { |
t->state = UNINTERRUPTIBLE; |
smp_mb(); ,-----> | (observes !COND)
| /
if (COND) ---------' | COND = 1;
break; `- if (t->state != RUNNING)
wake_up_process(t); // not done
schedule(); // forever waiting
}
t->state = TASK_RUNNING;
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Davidlohr Bueso <dbueso@suse.de>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20210611082838.160855222@infradead.org
Diffstat (limited to 'drivers/usb/gadget')
| -rw-r--r-- | drivers/usb/gadget/udc/max3420_udc.c | 15 |
1 files changed, 5 insertions, 10 deletions
diff --git a/drivers/usb/gadget/udc/max3420_udc.c b/drivers/usb/gadget/udc/max3420_udc.c index 35179543c327..34f4db554977 100644 --- a/drivers/usb/gadget/udc/max3420_udc.c +++ b/drivers/usb/gadget/udc/max3420_udc.c @@ -509,8 +509,7 @@ static irqreturn_t max3420_vbus_handler(int irq, void *dev_id) ? USB_STATE_POWERED : USB_STATE_NOTATTACHED); spin_unlock_irqrestore(&udc->lock, flags); - if (udc->thread_task && - udc->thread_task->state != TASK_RUNNING) + if (udc->thread_task) wake_up_process(udc->thread_task); return IRQ_HANDLED; @@ -529,8 +528,7 @@ static irqreturn_t max3420_irq_handler(int irq, void *dev_id) } spin_unlock_irqrestore(&udc->lock, flags); - if (udc->thread_task && - udc->thread_task->state != TASK_RUNNING) + if (udc->thread_task) wake_up_process(udc->thread_task); return IRQ_HANDLED; @@ -1093,8 +1091,7 @@ static int max3420_wakeup(struct usb_gadget *gadget) spin_unlock_irqrestore(&udc->lock, flags); - if (udc->thread_task && - udc->thread_task->state != TASK_RUNNING) + if (udc->thread_task) wake_up_process(udc->thread_task); return ret; } @@ -1117,8 +1114,7 @@ static int max3420_udc_start(struct usb_gadget *gadget, udc->todo |= UDC_START; spin_unlock_irqrestore(&udc->lock, flags); - if (udc->thread_task && - udc->thread_task->state != TASK_RUNNING) + if (udc->thread_task) wake_up_process(udc->thread_task); return 0; @@ -1137,8 +1133,7 @@ static int max3420_udc_stop(struct usb_gadget *gadget) udc->todo |= UDC_START; spin_unlock_irqrestore(&udc->lock, flags); - if (udc->thread_task && - udc->thread_task->state != TASK_RUNNING) + if (udc->thread_task) wake_up_process(udc->thread_task); return 0; |