diff options
| author | D. Wythe <alibuda@linux.alibaba.com> | 2021-12-15 20:29:21 +0800 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2021-12-16 08:11:05 -0800 |
| commit | 5c15b3123f65f8fbb1b445d9a7e8812e0e435df2 (patch) | |
| tree | 7ba5059d2d1833d5260448893f19ab40378afe65 /net | |
| parent | 8a03ef676ade55182f9b05115763aeda6dc08159 (diff) | |
net/smc: Prevent smc_release() from long blocking
In nginx/wrk benchmark, there's a hung problem with high probability
on case likes that: (client will last several minutes to exit)
server: smc_run nginx
client: smc_run wrk -c 10000 -t 1 http://server
Client hangs with the following backtrace:
0 [ffffa7ce8Of3bbf8] __schedule at ffffffff9f9eOd5f
1 [ffffa7ce8Of3bc88] schedule at ffffffff9f9eløe6
2 [ffffa7ce8Of3bcaO] schedule_timeout at ffffffff9f9e3f3c
3 [ffffa7ce8Of3bd2O] wait_for_common at ffffffff9f9el9de
4 [ffffa7ce8Of3bd8O] __flush_work at ffffffff9fOfeOl3
5 [ffffa7ce8øf3bdfO] smc_release at ffffffffcO697d24 [smc]
6 [ffffa7ce8Of3be2O] __sock_release at ffffffff9f8O2e2d
7 [ffffa7ce8Of3be4ø] sock_close at ffffffff9f8ø2ebl
8 [ffffa7ce8øf3be48] __fput at ffffffff9f334f93
9 [ffffa7ce8Of3be78] task_work_run at ffffffff9flOlff5
10 [ffffa7ce8Of3beaO] do_exit at ffffffff9fOe5Ol2
11 [ffffa7ce8Of3bflO] do_group_exit at ffffffff9fOe592a
12 [ffffa7ce8Of3bf38] __x64_sys_exit_group at ffffffff9fOe5994
13 [ffffa7ce8Of3bf4O] do_syscall_64 at ffffffff9f9d4373
14 [ffffa7ce8Of3bfsO] entry_SYSCALL_64_after_hwframe at ffffffff9fa0007c
This issue dues to flush_work(), which is used to wait for
smc_connect_work() to finish in smc_release(). Once lots of
smc_connect_work() was pending or all executing work dangling,
smc_release() has to block until one worker comes to free, which
is equivalent to wait another smc_connnect_work() to finish.
In order to fix this, There are two changes:
1. For those idle smc_connect_work(), cancel it from the workqueue; for
executing smc_connect_work(), waiting for it to finish. For that
purpose, replace flush_work() with cancel_work_sync().
2. Since smc_connect() hold a reference for passive closing, if
smc_connect_work() has been cancelled, release the reference.
Fixes: 24ac3a08e658 ("net/smc: rebuild nonblocking connect")
Reported-by: Tony Lu <tonylu@linux.alibaba.com>
Tested-by: Dust Li <dust.li@linux.alibaba.com>
Reviewed-by: Dust Li <dust.li@linux.alibaba.com>
Reviewed-by: Tony Lu <tonylu@linux.alibaba.com>
Signed-off-by: D. Wythe <alibuda@linux.alibaba.com>
Acked-by: Karsten Graul <kgraul@linux.ibm.com>
Link: https://lore.kernel.org/r/1639571361-101128-1-git-send-email-alibuda@linux.alibaba.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'net')
| -rw-r--r-- | net/smc/af_smc.c | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/net/smc/af_smc.c b/net/smc/af_smc.c index 230072f9ec48..1c9289f56dc4 100644 --- a/net/smc/af_smc.c +++ b/net/smc/af_smc.c @@ -194,7 +194,9 @@ static int smc_release(struct socket *sock) /* cleanup for a dangling non-blocking connect */ if (smc->connect_nonblock && sk->sk_state == SMC_INIT) tcp_abort(smc->clcsock->sk, ECONNABORTED); - flush_work(&smc->connect_work); + + if (cancel_work_sync(&smc->connect_work)) + sock_put(&smc->sk); /* sock_hold in smc_connect for passive closing */ if (sk->sk_state == SMC_LISTEN) /* smc_close_non_accepted() is called and acquires |