From: Kalle Valo <kvalo@codeaurora.org>
To: Luca Coelho <luca@coelho.fi>
Cc: linux-wireless@vger.kernel.org
Subject: Re: [PATCH 4/8] iwlwifi: mvm: fix race in sync rx queue notification
Date: Fri, 04 Oct 2019 16:41:12 +0300 [thread overview]
Message-ID: <87imp4sk5j.fsf@codeaurora.org> (raw)
In-Reply-To: <20191004131414.27372-5-luca@coelho.fi> (Luca Coelho's message of "Fri, 4 Oct 2019 16:14:10 +0300")
Luca Coelho <luca@coelho.fi> writes:
> From: Naftali Goldstein <naftali.goldstein@intel.com>
>
> Consider the following flow:
> 1. Driver starts to sync the rx queues due to a delba.
> mvm->queue_sync_cookie=1.
> This rx-queues-sync is synchronous, so it doesn't increment the
> cookie until all rx queues handle the notification from FW.
> 2. During this time, driver starts to sync rx queues due to nssn sync
> required.
> The cookie's value is still 1, but it doesn't matter since this
> rx-queue-sync is non-synchronous so in the notification handler the
> cookie is ignored.
> What _does_ matter is that this flow increments the cookie to 2
> immediately.
> Remember though that the FW won't start servicing this command until
> it's done with the previous one.
> 3. FW is still handling the first command, so it sends a notification
> with internal_notif->sync=1, and internal_notif->cookie=0, which
> triggers a WARN_ONCE.
>
> The solution for this race is to only use the mvm->queue_sync_cookie in
> case of a synchronous sync-rx-queues. This way in step 2 the cookie's
> value won't change so we avoid the WARN.
>
> The commit in the "fixes" field is the first commit to introduce
> non-synchronous sending of this command to FW.
But I don't see a Fixes field anywhere :)
--
Kalle Valo
next prev parent reply other threads:[~2019-10-04 13:41 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-04 13:14 [PATCH 0/8] iwlwifi: fixes intended for 5.4 2019-10-04 Luca Coelho
2019-10-04 13:14 ` [PATCH 1/8] iwlwifi: don't access trans_cfg via cfg Luca Coelho
2019-10-04 13:14 ` [PATCH 2/8] iwlwifi: fix ACPI table revision checks Luca Coelho
2019-10-04 13:14 ` [PATCH 3/8] iwlwifi: mvm: force single phy init Luca Coelho
2019-10-04 13:14 ` [PATCH 4/8] iwlwifi: mvm: fix race in sync rx queue notification Luca Coelho
2019-10-04 13:41 ` Kalle Valo [this message]
2019-10-04 18:06 ` Luca Coelho
2019-10-04 13:14 ` [PATCH 5/8] iwlwifi: pcie: fix indexing in command dump for new HW Luca Coelho
2019-10-04 13:14 ` [PATCH 6/8] iwlwifi: pcie: fix rb_allocator workqueue allocation Luca Coelho
2019-10-04 13:14 ` [PATCH 7/8] iwlwifi: dbg_ini: fix memory leak in alloc_sgtable Luca Coelho
2019-10-04 13:14 ` [PATCH 8/8] iwlwifi: pcie: fix memory leaks in iwl_pcie_ctxt_info_gen3_init Luca Coelho
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=87imp4sk5j.fsf@codeaurora.org \
--to=kvalo@codeaurora.org \
--cc=linux-wireless@vger.kernel.org \
--cc=luca@coelho.fi \
/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).