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

Dust Li
2023-11-01T08:13:36Z

On Wed, Nov 01, 2023 at 11:42:55AM +0800, D. Wythe wrote:
>From: "D. Wythe" <alibuda@linux.alibaba.com>
>
>Considering scenario:
>
> smc_cdc_rx_handler_rwwi
>__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.
>
>Signed-off-by: D. Wythe <alibuda@linux.alibaba.com>
>Reviewed-by: Wenjia Zhang <wenjia@linux.ibm.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