From: Kalle Valo <kvalo@codeaurora.org>
To: Wen Gong <wgong@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: Wed, 09 Dec 2020 11:24:04 +0200 [thread overview]
Message-ID: <87r1nzbadn.fsf@codeaurora.org> (raw)
In-Reply-To: <010101746bd17881-819242de-7cbb-4df3-93e2-59473d281155-000000@us-west-2.amazonses.com> (Wen Gong's message of "Tue, 8 Sep 2020 03:45:24 +0000")
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:
https://git.kernel.org/pub/scm/linux/kernel/git/kvalo/ath.git/commit/?h=pending&id=e0a466d296bd862080f7796b41349f9f586272c9
--
https://patchwork.kernel.org/project/linux-wireless/list/
https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches
next prev parent reply other threads:[~2020-12-09 9:25 UTC|newest]
Thread overview: 12+ 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 14:09 ` Krishna Chaitanya
2020-12-09 9:11 ` Kalle Valo
2020-09-07 16:23 ` Kalle Valo
[not found] ` <87d02x1rqb.fsf@codeaurora.org>
2020-09-08 3:45 ` Wen Gong
[not found] ` <010101746bd17881-819242de-7cbb-4df3-93e2-59473d281155-000000@us-west-2.amazonses.com>
2020-12-09 9:24 ` Kalle Valo [this message]
2020-12-09 15:00 ` Ben Greear
2020-12-10 2:29 ` Wen Gong
2020-12-15 8:05 ` Kalle Valo
2020-12-15 7:56 ` Kalle Valo
2020-12-10 2:27 ` Wen Gong
2020-12-17 6:52 ` Kalle Valo
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=87r1nzbadn.fsf@codeaurora.org \
--to=kvalo@codeaurora.org \
--cc=ath10k@lists.infradead.org \
--cc=linux-wireless@vger.kernel.org \
--cc=wgong@codeaurora.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).