From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from m43-7.mailgun.net ([69.72.43.7]) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1k7x9R-0007QV-Vt for ath10k@lists.infradead.org; Tue, 18 Aug 2020 08:39:31 +0000 MIME-Version: 1.0 Date: Tue, 18 Aug 2020 16:39:04 +0800 From: Wen Gong Subject: Re: [PATCH v4 1/2] ath10k: add refcount for ath10k_core_restart In-Reply-To: <87imdlkuw8.fsf@codeaurora.org> References: <20200108031957.22308-1-wgong@codeaurora.org> <20200108031957.22308-2-wgong@codeaurora.org> <87imdlkuw8.fsf@codeaurora.org> Message-ID: List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "ath10k" Errors-To: ath10k-bounces+kvalo=adurom.com@lists.infradead.org To: Kalle Valo Cc: linux-wireless@vger.kernel.org, ath10k@lists.infradead.org On 2020-08-15 01:19, Kalle Valo wrote: > Wen Gong writes: > ... >> diff --git a/drivers/net/wireless/ath/ath10k/core.c >> b/drivers/net/wireless/ath/ath10k/core.c >> index 91f131b87efc..0e31846e6c89 100644 >> --- a/drivers/net/wireless/ath/ath10k/core.c >> +++ b/drivers/net/wireless/ath/ath10k/core.c >> @@ -2199,6 +2199,14 @@ static void ath10k_core_restart(struct >> work_struct *work) >> { >> struct ath10k *ar = container_of(work, struct ath10k, restart_work); >> int ret; >> + int restart_count; >> + >> + restart_count = atomic_add_return(1, &ar->restart_count); >> + if (restart_count > 1) { >> + ath10k_warn(ar, "can not restart, count: %d\n", restart_count); >> + atomic_dec(&ar->restart_count); >> + return; >> + } > > I have been thinking a different approach for this. I think another > option is to have a function like this: > > ath10k_core_firmware_crashed() > { > queue_work(ar->workqueue, &ar->restart_work); > } > > In patch 1 we would convert all existing callers to call that > function instead of queue_work() directly. > > In patch 2 we would add a new flag to enum ath10k_dev_flags, or maybe > should actually use existing ATH10K_FLAG_CRASH_FLUSH? Don't know yet > which one is better. Now the function would do: > > ath10k_core_firmware_crashed() > { > if (test_bit(flag)) > return > > set_bit(flag) > queue_work(ar->workqueue, &ar->restart_work); > } > > That way restart_work queue would be called only one time. > This is not muti-thread-safe, for example, if 2 thread entered to the test_bit(flag) meanwhile and both check pass, then it will have 2 restart. atomic_add_return is muti-thread-safe, if 2 thread entered it, only 1 thread can pass the check, another will fail and return. The "payload length exceeds max htc length for sdio" happened many times in a very short time, so I add this check for it. > Though I'm not sure how ATH10K_STATE_WEDGED would behave after this > change, it might get broken. Ah, actually I think even this patch > breaks > the WEDGED state. This firmware restart is tricky, difficult to say > what > is the best approach. Michal, are you reading? :) Any ideas? > > And after looking more about this patch I don't see the need for the > new > ar->restart_count atomic variable. Checking for ATH10K_FLAG_CRASH_FLUSH > would do the same thing AFAICS. > > And related to this, (in a separate patch) I think we should utilise > ATH10K_FLAG_CRASH_FLUSH more. For example in ath10k_wmi_cmd_send() to > not even try to send a WMI command if the flag is set. Basically all > hardware access should be disabled except what is needed to restart the > firmware. _______________________________________________ ath10k mailing list ath10k@lists.infradead.org http://lists.infradead.org/mailman/listinfo/ath10k