[PATCH net v2 0/3] bugfixs for smc

[PATCH net v2 0/3] bugfixs for smc

[D. Wythe]

From: "D. Wythe" <alibuda@linux.alibaba.com>

This patches includes bugfix following:

1. hung state
2. sock leak
3. potential panic

We have been testing these patches for some time, but
if you have any questions, please let us know.

--
v1:
Fix spelling errors and incorrect function names in descriptions

v2->v1:
Add fix tags for bugfix patch

D. Wythe (3):
  net/smc: fix dangling sock under state SMC_APPFINCLOSEWAIT
  net/smc: allow cdc msg send rather than drop it with NULL sndbuf_desc
  net/smc: put sk reference if close work was canceled

 net/smc/af_smc.c    |  4 ++--
 net/smc/smc.h       |  5 +++++
 net/smc/smc_cdc.c   | 11 +++++------
 net/smc/smc_close.c |  5 +++--
 4 files changed, 15 insertions(+), 10 deletions(-)

-- 
1.8.3.1

[PATCH net v2 1/3] net/smc: fix dangling sock under state SMC_APPFINCLOSEWAIT

[D. Wythe]

From: "D. Wythe" <alibuda@linux.alibaba.com>

Considering scenario:

				smc_cdc_rx_handler
__smc_release
				sock_set_flag
smc_close_active()
sock_set_flag

__set_bit(DEAD)			__set_bit(DONE)

Dues to __set_bit is not atomic, the DEAD or DONE might be lost.
if the DEAD flag lost, the state SMC_CLOSED  will be never be reached
in smc_close_passive_work:

if (sock_flag(sk, SOCK_DEAD) &&
	smc_close_sent_any_close(conn)) {
	sk->sk_state = SMC_CLOSED;
} else {
	/* just shutdown, but not yet closed locally */
	sk->sk_state = SMC_APPFINCLOSEWAIT;
}

Replace sock_set_flags or __set_bit to set_bit will fix this problem.
Since set_bit is atomic.

Fixes: b38d732477e4 ("smc: socket closing and linkgroup cleanup")
Signed-off-by: D. Wythe <alibuda@linux.alibaba.com>
Reviewed-by: Dust Li <dust.li@linux.alibaba.com>
---
 net/smc/af_smc.c    | 4 ++--
 net/smc/smc.h       | 5 +++++
 net/smc/smc_cdc.c   | 2 +-
 net/smc/smc_close.c | 2 +-
 4 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/net/smc/af_smc.c b/net/smc/af_smc.c
index abd2667..da97f94 100644
--- a/net/smc/af_smc.c
+++ b/net/smc/af_smc.c
@@ -275,7 +275,7 @@ static int __smc_release(struct smc_sock *smc)
 
 	if (!smc->use_fallback) {
 		rc = smc_close_active(smc);
-		sock_set_flag(sk, SOCK_DEAD);
+		smc_sock_set_flag(sk, SOCK_DEAD);
 		sk->sk_shutdown |= SHUTDOWN_MASK;
 	} else {
 		if (sk->sk_state != SMC_CLOSED) {
@@ -1743,7 +1743,7 @@ static int smc_clcsock_accept(struct smc_sock *lsmc, struct smc_sock **new_smc)
 		if (new_clcsock)
 			sock_release(new_clcsock);
 		new_sk->sk_state = SMC_CLOSED;
-		sock_set_flag(new_sk, SOCK_DEAD);
+		smc_sock_set_flag(new_sk, SOCK_DEAD);
 		sock_put(new_sk); /* final */
 		*new_smc = NULL;
 		goto out;
diff --git a/net/smc/smc.h b/net/smc/smc.h
index 24745fd..e377980 100644
--- a/net/smc/smc.h
+++ b/net/smc/smc.h
@@ -377,4 +377,9 @@ void smc_fill_gid_list(struct smc_link_group *lgr,
 int smc_nl_enable_hs_limitation(struct sk_buff *skb, struct genl_info *info);
 int smc_nl_disable_hs_limitation(struct sk_buff *skb, struct genl_info *info);
 
+static inline void smc_sock_set_flag(struct sock *sk, enum sock_flags flag)
+{
+	set_bit(flag, &sk->sk_flags);
+}
+
 #endif	/* __SMC_H */
diff --git a/net/smc/smc_cdc.c b/net/smc/smc_cdc.c
index 89105e9..01bdb79 100644
--- a/net/smc/smc_cdc.c
+++ b/net/smc/smc_cdc.c
@@ -385,7 +385,7 @@ static void smc_cdc_msg_recv_action(struct smc_sock *smc,
 		smc->sk.sk_shutdown |= RCV_SHUTDOWN;
 		if (smc->clcsock && smc->clcsock->sk)
 			smc->clcsock->sk->sk_shutdown |= RCV_SHUTDOWN;
-		sock_set_flag(&smc->sk, SOCK_DONE);
+		smc_sock_set_flag(&smc->sk, SOCK_DONE);
 		sock_hold(&smc->sk); /* sock_put in close_work */
 		if (!queue_work(smc_close_wq, &conn->close_work))
 			sock_put(&smc->sk);
diff --git a/net/smc/smc_close.c b/net/smc/smc_close.c
index dbdf03e..449ef45 100644
--- a/net/smc/smc_close.c
+++ b/net/smc/smc_close.c
@@ -173,7 +173,7 @@ void smc_close_active_abort(struct smc_sock *smc)
 		break;
 	}
 
-	sock_set_flag(sk, SOCK_DEAD);
+	smc_sock_set_flag(sk, SOCK_DEAD);
 	sk->sk_state_change(sk);
 
 	if (release_clcsock) {
-- 
1.8.3.1

[PATCH net v2 2/3] net/smc: allow cdc msg send rather than drop it with NULL sndbuf_desc

[D. Wythe]

From: "D. Wythe" <alibuda@linux.alibaba.com>

This patch re-fix the issues mentioned by commit 22a825c541d7
("net/smc: fix NULL sndbuf_desc in smc_cdc_tx_handler()").

Blocking sending message do solve the issues though, but it also
prevents the peer to receive the final message. Besides, in logic,
whether the sndbuf_desc is NULL or not have no impact on the processing
of cdc message sending.

Hence that, this patch allows the cdc message sending but to check the
sndbuf_desc with care in smc_cdc_tx_handler().

Fixes: 22a825c541d7 ("net/smc: fix NULL sndbuf_desc in smc_cdc_tx_handler()")
Signed-off-by: D. Wythe <alibuda@linux.alibaba.com>
Reviewed-by: Dust Li <dust.li@linux.alibaba.com>
---
 net/smc/smc_cdc.c | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/net/smc/smc_cdc.c b/net/smc/smc_cdc.c
index 01bdb79..3c06625 100644
--- a/net/smc/smc_cdc.c
+++ b/net/smc/smc_cdc.c
@@ -28,13 +28,15 @@ static void smc_cdc_tx_handler(struct smc_wr_tx_pend_priv *pnd_snd,
 {
 	struct smc_cdc_tx_pend *cdcpend = (struct smc_cdc_tx_pend *)pnd_snd;
 	struct smc_connection *conn = cdcpend->conn;
+	struct smc_buf_desc *sndbuf_desc;
 	struct smc_sock *smc;
 	int diff;
 
+	sndbuf_desc = conn->sndbuf_desc;
 	smc = container_of(conn, struct smc_sock, conn);
 	bh_lock_sock(&smc->sk);
-	if (!wc_status) {
-		diff = smc_curs_diff(cdcpend->conn->sndbuf_desc->len,
+	if (!wc_status && sndbuf_desc) {
+		diff = smc_curs_diff(sndbuf_desc->len,
 				     &cdcpend->conn->tx_curs_fin,
 				     &cdcpend->cursor);
 		/* sndbuf_space is decreased in smc_sendmsg */
@@ -114,9 +116,6 @@ int smc_cdc_msg_send(struct smc_connection *conn,
 	union smc_host_cursor cfed;
 	int rc;
 
-	if (unlikely(!READ_ONCE(conn->sndbuf_desc)))
-		return -ENOBUFS;
-
 	smc_cdc_add_pending_send(conn, pend);
 
 	conn->tx_cdc_seq++;
-- 
1.8.3.1

[PATCH net v2 3/3] net/smc: put sk reference if close work was canceled

[D. Wythe]

From: "D. Wythe" <alibuda@linux.alibaba.com>

Note that we always hold a reference to sock when attempting
to submit close_work. Therefore, if we have successfully
canceled close_work from pending, we MUST release that reference
to avoid potential leaks.

Fixes: 42bfba9eaa33 ("net/smc: immediate termination for SMCD link groups")
Signed-off-by: D. Wythe <alibuda@linux.alibaba.com>
Reviewed-by: Dust Li <dust.li@linux.alibaba.com>
---
 net/smc/smc_close.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/smc/smc_close.c b/net/smc/smc_close.c
index 449ef45..10219f5 100644
--- a/net/smc/smc_close.c
+++ b/net/smc/smc_close.c
@@ -116,7 +116,8 @@ static void smc_close_cancel_work(struct smc_sock *smc)
 	struct sock *sk = &smc->sk;
 
 	release_sock(sk);
-	cancel_work_sync(&smc->conn.close_work);
+	if (cancel_work_sync(&smc->conn.close_work))
+		sock_put(sk);
 	cancel_delayed_work_sync(&smc->conn.tx_work);
 	lock_sock(sk);
 }
-- 
1.8.3.1

Re: [PATCH net v2 0/3] bugfixs for smc

[Wenjia Zhang]

On 03.11.23 07:07, D. Wythe wrote:
> From: "D. Wythe" <alibuda@linux.alibaba.com>
> 
> This patches includes bugfix following:
> 
> 1. hung state
> 2. sock leak
> 3. potential panic
> 
> We have been testing these patches for some time, but
> if you have any questions, please let us know.
> 
> --
> v1:
> Fix spelling errors and incorrect function names in descriptions
> 
> v2->v1:
> Add fix tags for bugfix patch
> 
> D. Wythe (3):
>    net/smc: fix dangling sock under state SMC_APPFINCLOSEWAIT
>    net/smc: allow cdc msg send rather than drop it with NULL sndbuf_desc
>    net/smc: put sk reference if close work was canceled
> 
>   net/smc/af_smc.c    |  4 ++--
>   net/smc/smc.h       |  5 +++++
>   net/smc/smc_cdc.c   | 11 +++++------
>   net/smc/smc_close.c |  5 +++--
>   4 files changed, 15 insertions(+), 10 deletions(-)
> 

Thank you for the fixes, LGTM! For all of the 3 pathces:

Reviewed-by: Wenjia Zhang <wenjia@linux.ibm.com>

Re: [PATCH net v2 0/3] bugfixs for smc

[patchwork-bot+netdevbpf]

Hello:

This series was applied to netdev/net.git (main)
by David S. Miller <davem@davemloft.net>:

On Fri,  3 Nov 2023 14:07:37 +0800 you wrote:
> From: "D. Wythe" <alibuda@linux.alibaba.com>
> 
> This patches includes bugfix following:
> 
> 1. hung state
> 2. sock leak
> 3. potential panic
> 
> [...]

Here is the summary with links:
  - [net,v2,1/3] net/smc: fix dangling sock under state SMC_APPFINCLOSEWAIT
    https://git.kernel.org/netdev/net/c/5211c9729484
  - [net,v2,2/3] net/smc: allow cdc msg send rather than drop it with NULL sndbuf_desc
    https://git.kernel.org/netdev/net/c/c5bf605ba4f9
  - [net,v2,3/3] net/smc: put sk reference if close work was canceled
    https://git.kernel.org/netdev/net/c/aa96fbd6d78d

You are awesome, thank you!
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