Daniel Wagner <wagi@xxxxxxxxx> wrote: > From: Daniel Wagner <daniel.wagner@xxxxxxxxxxxx> > > carl9170_usb_stop() is used from several places to flush and cleanup any > pending work. The normal pattern is to send a request and wait for the > irq handler to call complete(). The completion is not reinitialized > during normal operation and as the old comment indicates it is important > to keep calls to wait_for_completion_timeout() and complete() balanced. > > Calling complete_all() brings this equilibirum out of balance and needs > to be fixed by a reinit_completion(). But that opens a small race > window. It is possible that the sequence of complete_all(), > reinit_completion() is faster than the wait_for_completion_timeout() can > do its work. The wake up is not lost but the done counter test is after > reinit_completion() has been executed. The only reason we don't see > carl9170_exec_cmd() hang forever is we use the timeout version of > wait_for_copletion(). > > Let's fix this by reinitializing the completion (that is just setting > done counter to 0) just before we send out an request. Now, > carl9170_usb_stop() can be sure a complete() call is enough to make > progess since there is only one waiter at max. This is a common pattern > also seen in various drivers which use completion. > > Signed-off-by: Daniel Wagner <daniel.wagner@xxxxxxxxxxxx> Thanks, 1 patch applied to ath-next branch of ath.git: 78a9e170388b carl9170: Fix wrong completion usage -- Sent by pwcli https://patchwork.kernel.org/patch/9287819/
