[PATCH net v2] net/smc: Don't call clcsock shutdown twice when smc shutdown

[PATCH net v2] net/smc: Don't call clcsock shutdown twice when smc shutdown

[Tony Lu]

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>
---

changes:

v1->v2:
- code format
- use bool do_shutdown

---
 net/smc/af_smc.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/net/smc/af_smc.c b/net/smc/af_smc.c
index 4b62c925a13e..9fd350fa22ba 100644
--- a/net/smc/af_smc.c
+++ b/net/smc/af_smc.c
@@ -2370,8 +2370,10 @@ static __poll_t 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);
@@ -2398,7 +2400,12 @@ 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);
@@ -2408,7 +2415,7 @@ 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;
-- 
2.32.0.3.g01195cf9f

Re: [PATCH net v2] net/smc: Don't call clcsock shutdown twice when smc shutdown

[Karsten Graul]

On 25/11/2021 14:24, Tony Lu wrote:
> @@ -2398,7 +2400,12 @@ 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;

Please send a v3 without the extra empty line before the break statement,
and then the patch is fine with me.

Thank you!

Re: [PATCH net v2] net/smc: Don't call clcsock shutdown twice when smc shutdown

[Tony Lu]

On Thu, Nov 25, 2021 at 03:51:06PM +0100, Karsten Graul wrote:
> On 25/11/2021 14:24, Tony Lu wrote:
> > @@ -2398,7 +2400,12 @@ 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;
> 
> Please send a v3 without the extra empty line before the break statement,
> and then the patch is fine with me.
> 
> Thank you!

I will fix it, and send it out soon.

Thanks,
Tony Lu