[PATCH 4.14 028/106] net/smc: Dont call clcsock shutdown twice when smc shutdown

Greg Kroah-Hartman
2021-12-06T15:08:08Z

From: Tony Lu <tonylu@linux.alibaba.com>

[ Upstream commit bacb6c1e47691cda4a95056c21b5487fb7199fcc ]

When applications call shutdown() with SHUT_RDWR in userspace,
smc_close_active() calls kernel_sock_shutdown(), and it is called
twice in smc_shutdown().

This fixes this by checking sk_state before do clcsock shutdown, and
avoids missing the application's call of smc_shutdown().

Link: https://lore.kernel.org/linux-s390/1f67548e-cbf6-0dce-82b5-10288a4583bd@linux.ibm.com/
Fixes: 606a63c9783a ("net/smc: Ensure the active closing peer first closes clcsock")
Signed-off-by: Tony Lu <tonylu@linux.alibaba.com>
Reviewed-by: Wen Gu <guwen@linux.alibaba.com>
Acked-by: Karsten Graul <kgraul@linux.ibm.com>
Link: https://lore.kernel.org/r/20211126024134.45693-1-tonylu@linux.alibaba.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
net/smc/af_smc.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/net/smc/af_smc.c b/net/smc/af_smc.c
index 8c71f0929fbb7..f2c907d52812b 100644
--- a/net/smc/af_smc.c
+++ b/net/smc/af_smc.c
@@ -1178,8 +1178,10 @@ static unsigned int smc_poll(struct file *file, struct socket *sock,
static int smc_shutdown(struct socket *sock, int how)
{
struct sock *sk = sock->sk;
+ bool do_shutdown = true;
struct smc_sock *smc;
int rc = -EINVAL;
+ int old_state;
int rc1 = 0;

smc = smc_sk(sk);
@@ -1206,7 +1208,11 @@ static int smc_shutdown(struct socket *sock, int how)
}
switch (how) {
case SHUT_RDWR: /* shutdown in both directions */
+ old_state = sk->sk_state;
rc = smc_close_active(smc);
+ if (old_state == SMC_ACTIVE &&
+ sk->sk_state == SMC_PEERCLOSEWAIT1)
+ do_shutdown = false;
break;
case SHUT_WR:
rc = smc_close_shutdown_write(smc);
@@ -1216,7 +1222,7 @@ static int smc_shutdown(struct socket *sock, int how)
/* nothing more to do because peer is not involved */
break;
}
- if (smc->clcsock)
+ if (do_shutdown && smc->clcsock)
rc1 = kernel_sock_shutdown(smc->clcsock, how);
/* map sock_shutdown_cmd constants to sk_shutdown value range */
sk->sk_shutdown |= how + 1;
--
2.33.0