Hi,
Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> writes:
> On Fri, 2 Sep 2016, Felipe Balbi wrote:
>
>>
>> Hi,
>>
>> Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> writes:
>>
>> [...]
>>
>> > No, that would be too late. The barrier needs to go between the write
>> > to common->thead_wakeup_needed and the call to wake_up_process().
>>
>> alright, I tested this but it doesn't work. It still hangs :-(
>
> Okay, I was wrong. But see my recent reply to Paul; maybe the
> smp_wmb() in wakeup_thread() needs to be smp_mb().
okay, this seems to be working so far:
modified drivers/usb/gadget/function/f_mass_storage.c
@@ -395,7 +395,7 @@ static int fsg_set_halt(struct fsg_dev *fsg, struct usb_ep *ep)
/* Caller must hold fsg->lock */
static void wakeup_thread(struct fsg_common *common)
{
- smp_wmb(); /* ensure the write of bh->state is complete */
+ smp_mb(); /* ensure the write of bh->state is complete */
/* Tell the main thread that something has happened */
common->thread_wakeup_needed = 1;
if (common->thread_task)
@@ -626,7 +626,7 @@ static int sleep_thread(struct fsg_common *common, bool can_freeze)
}
__set_current_state(TASK_RUNNING);
common->thread_wakeup_needed = 0;
- smp_rmb(); /* ensure the latest bh->state is visible */
+ smp_mb(); /* ensure the latest bh->state is visible */
return rc;
}
I'll keep it running over the weekend.
thanks
--
balbi
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