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From: Wen Gong <wgong@codeaurora.org>
To: Kalle Valo <kvalo@codeaurora.org>
Cc: linux-wireless@vger.kernel.org, ath10k@lists.infradead.org
Subject: Re: [PATCH v3] ath10k: add flag to protect napi operation to avoid dead loop hang
Date: Thu, 10 Dec 2020 10:27:31 +0800	[thread overview]
Message-ID: <2babbd5a3c48d41c2ef19371cc982784@codeaurora.org> (raw)
In-Reply-To: <87r1nzbadn.fsf@codeaurora.org>

On 2020-12-09 17:24, Kalle Valo wrote:
> Wen Gong <wgong@codeaurora.org> writes:
> 
>> On 2020-09-08 00:22, Kalle Valo wrote:
>> 
>>> Just like with the recent firmware restart patch, isn't
>>> ar->napi_enabled
>>> racy? Wouldn't test_and_set_bit() and test_and_clear_bit() be safer?
>>> 
>>> Or are we holding a lock? But then that should be documented with
>>> lockdep_assert_held().
>> 
>> yes, ath10k_hif_start is only called from ath10k_core_start, it has
>> "lockdep_assert_held(&ar->conf_mutex)", and ath10k_hif_stop is only
>> called from ath10k_core_stop, it also has
>> "lockdep_assert_held(&ar->conf_mutex)". then it will not 2 thread both
>> enter ath10k_hif_start/ath10k_hif_stop meanwhile.
> 
> Ok, but every function depending on a lock being held should still call
> lockdep_assert_held(), that way we can catch the bug if locking changes
> later. So it's not enough that ath10k_core_stop() has
> lockdep_assert_held(), also these napi functions should have it.
> 
> I actually decided to switch using ATH10K_FLAG_NAPI_ENABLED with
> set_bit() & co, simpler locking that way and no lockdep_assert_held()
> needed anymore. Please check my changes in the pending branch, I have
> only compile tested them:
I checked, it only changed ar->napi_enabled to flag 
ATH10K_FLAG_NAPI_ENABLED,
not found probelm.
> 
> https://git.kernel.org/pub/scm/linux/kernel/git/kvalo/ath.git/commit/?h=pending&id=e0a466d296bd862080f7796b41349f9f586272c9

WARNING: multiple messages have this Message-ID (diff)
From: Wen Gong <wgong@codeaurora.org>
To: Kalle Valo <kvalo@codeaurora.org>
Cc: linux-wireless@vger.kernel.org, ath10k@lists.infradead.org
Subject: Re: [PATCH v3] ath10k: add flag to protect napi operation to avoid dead loop hang
Date: Thu, 10 Dec 2020 10:27:31 +0800	[thread overview]
Message-ID: <2babbd5a3c48d41c2ef19371cc982784@codeaurora.org> (raw)
In-Reply-To: <87r1nzbadn.fsf@codeaurora.org>

On 2020-12-09 17:24, Kalle Valo wrote:
> Wen Gong <wgong@codeaurora.org> writes:
> 
>> On 2020-09-08 00:22, Kalle Valo wrote:
>> 
>>> Just like with the recent firmware restart patch, isn't
>>> ar->napi_enabled
>>> racy? Wouldn't test_and_set_bit() and test_and_clear_bit() be safer?
>>> 
>>> Or are we holding a lock? But then that should be documented with
>>> lockdep_assert_held().
>> 
>> yes, ath10k_hif_start is only called from ath10k_core_start, it has
>> "lockdep_assert_held(&ar->conf_mutex)", and ath10k_hif_stop is only
>> called from ath10k_core_stop, it also has
>> "lockdep_assert_held(&ar->conf_mutex)". then it will not 2 thread both
>> enter ath10k_hif_start/ath10k_hif_stop meanwhile.
> 
> Ok, but every function depending on a lock being held should still call
> lockdep_assert_held(), that way we can catch the bug if locking changes
> later. So it's not enough that ath10k_core_stop() has
> lockdep_assert_held(), also these napi functions should have it.
> 
> I actually decided to switch using ATH10K_FLAG_NAPI_ENABLED with
> set_bit() & co, simpler locking that way and no lockdep_assert_held()
> needed anymore. Please check my changes in the pending branch, I have
> only compile tested them:
I checked, it only changed ar->napi_enabled to flag 
ATH10K_FLAG_NAPI_ENABLED,
not found probelm.
> 
> https://git.kernel.org/pub/scm/linux/kernel/git/kvalo/ath.git/commit/?h=pending&id=e0a466d296bd862080f7796b41349f9f586272c9

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  parent reply	other threads:[~2020-12-10  2:28 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-08-28 12:22 [PATCH v3] ath10k: add flag to protect napi operation to avoid dead loop hang Wen Gong
2020-08-28 12:22 ` Wen Gong
2020-08-28 14:09 ` Krishna Chaitanya
2020-08-28 14:09   ` Krishna Chaitanya
2020-12-09  9:11   ` Kalle Valo
2020-12-09  9:11     ` Kalle Valo
2020-09-07 16:23 ` Kalle Valo
2020-09-07 16:23 ` Kalle Valo
     [not found] ` <87d02x1rqb.fsf@codeaurora.org>
2020-09-08  3:45   ` Wen Gong
2020-12-09  9:24     ` Kalle Valo
2020-12-09  9:24       ` Kalle Valo
2020-12-09 15:00       ` Ben Greear
2020-12-09 15:00         ` Ben Greear
2020-12-10  2:29         ` Wen Gong
2020-12-10  2:29           ` Wen Gong
2020-12-15  8:05           ` Kalle Valo
2020-12-15  8:05             ` Kalle Valo
2020-12-15  7:56         ` Kalle Valo
2020-12-15  7:56           ` Kalle Valo
2020-12-10  2:27       ` Wen Gong [this message]
2020-12-10  2:27         ` Wen Gong
2020-09-08  3:45   ` Wen Gong
2020-12-17  6:52 ` Kalle Valo
2020-12-17  6:52 ` Kalle Valo

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