From: Xin Long <lucien.xin@gmail.com>
To: network dev <netdev@vger.kernel.org>, linux-sctp@vger.kernel.org
Cc: davem@davemloft.net, Eric Dumazet <edumazet@google.com>,
Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>,
Neil Horman <nhorman@tuxdriver.com>
Subject: [PATCHv2 net] sctp: not disable bh in the whole sctp_get_port_local()
Date: Fri, 21 Aug 2020 06:59:38 +0000 [thread overview]
Message-ID: <08a14c2f087153c18c67965cc37ed2ac22da18ed.1597993178.git.lucien.xin@gmail.com> (raw)
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>
---
net/sctp/socket.c | 16 ++++++----------
1 file changed, 6 insertions(+), 10 deletions(-)
diff --git a/net/sctp/socket.c b/net/sctp/socket.c
index ec1fba1..836615f 100644
--- a/net/sctp/socket.c
+++ b/net/sctp/socket.c
@@ -8060,8 +8060,6 @@ static int sctp_get_port_local(struct sock *sk, union sctp_addr *addr)
pr_debug("%s: begins, snum:%d\n", __func__, snum);
- local_bh_disable();
-
if (snum = 0) {
/* Search for an available port. */
int low, high, remaining, index;
@@ -8079,20 +8077,21 @@ static int sctp_get_port_local(struct sock *sk, union sctp_addr *addr)
continue;
index = sctp_phashfn(net, rover);
head = &sctp_port_hashtable[index];
- spin_lock(&head->lock);
+ spin_lock_bh(&head->lock);
sctp_for_each_hentry(pp, &head->chain)
if ((pp->port = rover) &&
net_eq(net, pp->net))
goto next;
break;
next:
- spin_unlock(&head->lock);
+ spin_unlock_bh(&head->lock);
+ cond_resched();
} while (--remaining > 0);
/* Exhausted local port range during search? */
ret = 1;
if (remaining <= 0)
- goto fail;
+ return ret;
/* OK, here is the one we will use. HEAD (the port
* hash table list entry) is non-NULL and we hold it's
@@ -8107,7 +8106,7 @@ static int sctp_get_port_local(struct sock *sk, union sctp_addr *addr)
* port iterator, pp being NULL.
*/
head = &sctp_port_hashtable[sctp_phashfn(net, snum)];
- spin_lock(&head->lock);
+ spin_lock_bh(&head->lock);
sctp_for_each_hentry(pp, &head->chain) {
if ((pp->port = snum) && net_eq(pp->net, net))
goto pp_found;
@@ -8207,10 +8206,7 @@ static int sctp_get_port_local(struct sock *sk, union sctp_addr *addr)
ret = 0;
fail_unlock:
- spin_unlock(&head->lock);
-
-fail:
- local_bh_enable();
+ spin_unlock_bh(&head->lock);
return ret;
}
--
2.1.0
next reply other threads:[~2020-08-21 6:59 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-21 6:59 Xin Long [this message]
2020-08-21 20:07 ` [PATCHv2 net] sctp: not disable bh in the whole sctp_get_port_local() Marcelo Ricardo Leitner
2020-08-24 22:51 ` David Miller
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