From: David Miller <davem@davemloft.net>
To: lucien.xin@gmail.com
Cc: netdev@vger.kernel.org, linux-sctp@vger.kernel.org,
edumazet@google.com, marcelo.leitner@gmail.com,
nhorman@tuxdriver.com
Subject: Re: [PATCHv2 net] sctp: not disable bh in the whole sctp_get_port_local()
Date: Mon, 24 Aug 2020 22:51:08 +0000 [thread overview]
Message-ID: <20200824.155108.8657858310039234.davem@davemloft.net> (raw)
In-Reply-To: <08a14c2f087153c18c67965cc37ed2ac22da18ed.1597993178.git.lucien.xin@gmail.com>
From: Xin Long <lucien.xin@gmail.com>
Date: Fri, 21 Aug 2020 14:59:38 +0800
> With disabling bh in the whole sctp_get_port_local(), when
> snum = 0 and too many ports have been used, the do-while
> loop will take the cpu for a long time and cause cpu stuck:
>
> [ ] watchdog: BUG: soft lockup - CPU#11 stuck for 22s!
> [ ] RIP: 0010:native_queued_spin_lock_slowpath+0x4de/0x940
> [ ] Call Trace:
> [ ] _raw_spin_lock+0xc1/0xd0
> [ ] sctp_get_port_local+0x527/0x650 [sctp]
> [ ] sctp_do_bind+0x208/0x5e0 [sctp]
> [ ] sctp_autobind+0x165/0x1e0 [sctp]
> [ ] sctp_connect_new_asoc+0x355/0x480 [sctp]
> [ ] __sctp_connect+0x360/0xb10 [sctp]
>
> There's no need to disable bh in the whole function of
> sctp_get_port_local. So fix this cpu stuck by removing
> local_bh_disable() called at the beginning, and using
> spin_lock_bh() instead.
>
> The same thing was actually done for inet_csk_get_port() in
> Commit ea8add2b1903 ("tcp/dccp: better use of ephemeral
> ports in bind()").
>
> Thanks to Marcelo for pointing the buggy code out.
>
> v1->v2:
> - use cond_resched() to yield cpu to other tasks if needed,
> as Eric noticed.
>
> Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
> Reported-by: Ying Xu <yinxu@redhat.com>
> Signed-off-by: Xin Long <lucien.xin@gmail.com>
Applied and queued up for -stable, thank you.
prev parent reply other threads:[~2020-08-24 22:51 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-21 6:59 [PATCHv2 net] sctp: not disable bh in the whole sctp_get_port_local() Xin Long
2020-08-21 20:07 ` Marcelo Ricardo Leitner
2020-08-24 22:51 ` David Miller [this message]
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