From: Johannes Berg <johannes@sipsolutions.net>
To: linux-wireless@vger.kernel.org
Subject: question for mac80211 driver maintainers - RCU usage in drivers
Date: Wed, 04 Dec 2013 22:30:10 +0100 [thread overview]
Message-ID: <1386192610.5660.4.camel@jlt4.sipsolutions.net> (raw)
Hi all,
Except for iwlmvm, I don't find much RCU usage wrt. stations in drivers.
Is there any other driver that assumes it is safe to delete a station
pointer in the sta_state callback and not use synchronize_rcu()? From
looking at the code, I don't see any, but I can't really be sure that
everyone uses __rcu annotations correctly ... :)
Would anyone object if we changed mac80211 to *immediately* free the
station after calling the driver's sta_state (or sta_remove) callback?
We currently delay this until after an RCU grace period, but that way we
end up having a lot of delay in station freeing ... We'd like to
optimise that.
johannes
PS: I'll probably have to add another callback "sta going away before
RCU" so you can invalidate pointers there ... otherwise I'd have to
synchronize_rcu() in iwlmvm which would kinda defeat the purpose.
next reply other threads:[~2013-12-04 21:30 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-12-04 21:30 Johannes Berg [this message]
2013-12-04 22:16 ` question for mac80211 driver maintainers - RCU usage in drivers Christian Lamparter
2013-12-04 22:23 ` Johannes Berg
2013-12-04 22:47 ` Christian Lamparter
2013-12-04 22:51 ` Johannes Berg
2013-12-05 12:35 ` [PATCH 0/8] mac80211: speed up station cleanup/AP shutdown Johannes Berg
2013-12-05 12:35 ` [PATCH 1/8] mac80211: add pre-RCU-sync sta removal driver operation Johannes Berg
2013-12-05 12:35 ` [PATCH 2/8] iwlwifi: mvm: use pre-RCU-sync sta removal operation Johannes Berg
2013-12-05 12:35 ` [PATCH 3/8] mac80211: move 4-addr sta pointer clearing before synchronize_rcu() Johannes Berg
2013-12-05 12:35 ` [PATCH 4/8] mac80211: don't delay station destruction Johannes Berg
2013-12-05 12:35 ` [PATCH 5/8] mac80211: move synchronize_net() before sta key removal Johannes Berg
2013-12-05 12:35 ` [PATCH 6/8] mac80211: optimise synchronize_net() for sta_info_flush Johannes Berg
2013-12-05 12:35 ` [PATCH 7/8] mac80211: optimise mixed AP/VLAN station removal Johannes Berg
2013-12-05 12:35 ` [PATCH 8/8] mac80211: free all AP/VLAN keys at once Johannes Berg
2013-12-05 17:02 ` [PATCH 0/8] mac80211: speed up station cleanup/AP shutdown Christian Lamparter
2013-12-05 17:27 ` Johannes Berg
2013-12-16 10:30 ` Johannes Berg
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