net/smc: wait for pending work before clcsock release_sock

When the clcsock is already released using sock_release() and a pending
smc_listen_work accesses the clcsock than that will fail. Solve this
by canceling and waiting for the work to complete first. Because the
work holds the sock_lock it must make sure that the lock is not hold
before the new helper smc_clcsock_release() is invoked. And before the
smc_listen_work starts working check if the parent listen socket is
still valid, otherwise stop the work early.

Signed-off-by: Karsten Graul <kgraul@linux.ibm.com>
Signed-off-by: Ursula Braun <ubraun@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/smc/af_smc.c b/net/smc/af_smc.c
index 77ef535..9bdaed2 100644 (file)
--- a/net/smc/af_smc.c
+++ b/net/smc/af_smc.c
@@ -167,10 +167,9 @@ static int smc_release(struct socket *sock)
 
        if (sk->sk_state == SMC_CLOSED) {
                if (smc->clcsock) {
-                       mutex_lock(&smc->clcsock_release_lock);
-                       sock_release(smc->clcsock);
-                       smc->clcsock = NULL;
-                       mutex_unlock(&smc->clcsock_release_lock);
+                       release_sock(sk);
+                       smc_clcsock_release(smc);
+                       lock_sock(sk);
                }
                if (!smc->use_fallback)
                        smc_conn_free(&smc->conn);
@@ -1037,13 +1036,13 @@ static void smc_listen_out(struct smc_sock *new_smc)
        struct smc_sock *lsmc = new_smc->listen_smc;
        struct sock *newsmcsk = &new_smc->sk;
 
-       lock_sock_nested(&lsmc->sk, SINGLE_DEPTH_NESTING);
        if (lsmc->sk.sk_state == SMC_LISTEN) {
+               lock_sock_nested(&lsmc->sk, SINGLE_DEPTH_NESTING);
                smc_accept_enqueue(&lsmc->sk, newsmcsk);
+               release_sock(&lsmc->sk);
        } else { /* no longer listening */
                smc_close_non_accepted(newsmcsk);
        }
-       release_sock(&lsmc->sk);
 
        /* Wake up accept */
        lsmc->sk.sk_data_ready(&lsmc->sk);
@@ -1237,6 +1236,9 @@ static void smc_listen_work(struct work_struct *work)
        int rc = 0;
        u8 ibport;
 
+       if (new_smc->listen_smc->sk.sk_state != SMC_LISTEN)
+               return smc_listen_out_err(new_smc);
+
        if (new_smc->use_fallback) {
                smc_listen_out_connected(new_smc);
                return;

diff --git a/net/smc/smc_close.c b/net/smc/smc_close.c
index 2ad37e9..fc06720 100644 (file)
--- a/net/smc/smc_close.c
+++ b/net/smc/smc_close.c
@@ -21,6 +21,22 @@
 
 #define SMC_CLOSE_WAIT_LISTEN_CLCSOCK_TIME     (5 * HZ)
 
+/* release the clcsock that is assigned to the smc_sock */
+void smc_clcsock_release(struct smc_sock *smc)
+{
+       struct socket *tcp;
+
+       if (smc->listen_smc && current_work() != &smc->smc_listen_work)
+               cancel_work_sync(&smc->smc_listen_work);
+       mutex_lock(&smc->clcsock_release_lock);
+       if (smc->clcsock) {
+               tcp = smc->clcsock;
+               smc->clcsock = NULL;
+               sock_release(tcp);
+       }
+       mutex_unlock(&smc->clcsock_release_lock);
+}
+
 static void smc_close_cleanup_listen(struct sock *parent)
 {
        struct sock *sk;
@@ -321,6 +337,7 @@ static void smc_close_passive_work(struct work_struct *work)
                                                   close_work);
        struct smc_sock *smc = container_of(conn, struct smc_sock, conn);
        struct smc_cdc_conn_state_flags *rxflags;
+       bool release_clcsock = false;
        struct sock *sk = &smc->sk;
        int old_state;
 
@@ -400,13 +417,13 @@ wakeup:
                if ((sk->sk_state == SMC_CLOSED) &&
                    (sock_flag(sk, SOCK_DEAD) || !sk->sk_socket)) {
                        smc_conn_free(conn);
-                       if (smc->clcsock) {
-                               sock_release(smc->clcsock);
-                               smc->clcsock = NULL;
-                       }
+                       if (smc->clcsock)
+                               release_clcsock = true;
                }
        }
        release_sock(sk);
+       if (release_clcsock)
+               smc_clcsock_release(smc);
        sock_put(sk); /* sock_hold done by schedulers of close_work */
 }
 

diff --git a/net/smc/smc_close.h b/net/smc/smc_close.h
index 19eb6a2..e0e3b5d 100644 (file)
--- a/net/smc/smc_close.h
+++ b/net/smc/smc_close.h
@@ -23,5 +23,6 @@ void smc_close_wake_tx_prepared(struct smc_sock *smc);
 int smc_close_active(struct smc_sock *smc);
 int smc_close_shutdown_write(struct smc_sock *smc);
 void smc_close_init(struct smc_sock *smc);
+void smc_clcsock_release(struct smc_sock *smc);
 
 #endif /* SMC_CLOSE_H */