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authorKarsten Graul <kgraul@linux.ibm.com>2019-01-30 18:51:02 +0100
committerDavid S. Miller <davem@davemloft.net>2019-02-01 14:45:44 -0800
commit77f838ace755d2f466536c44dac6c856f62cd901 (patch)
tree552f02d5012cfa872e0255fa8640e373d8281e24
parentca8dc1334a71d6081b09e18d55198a27e28fd44b (diff)
downloadlinux-77f838ace755d2f466536c44dac6c856f62cd901.tar.gz
net/smc: prevent races between smc_lgr_terminate() and smc_conn_free()
To prevent races between smc_lgr_terminate() and smc_conn_free() add an
extra check of the lgr field before accessing it, and cancel a delayed
free_work when a new smc connection is created.
This fixes the problem that free_work cleared the lgr variable but
smc_lgr_terminate() or smc_conn_free() still access it in parallel.

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>
-rw-r--r--net/smc/smc_core.c4
1 files changed, 4 insertions, 0 deletions
diff --git a/net/smc/smc_core.c b/net/smc/smc_core.c
index 35c1cdc93e1c..097c798983ca 100644
--- a/net/smc/smc_core.c
+++ b/net/smc/smc_core.c
@@ -128,6 +128,8 @@ static void smc_lgr_unregister_conn(struct smc_connection *conn)
 {
 	struct smc_link_group *lgr = conn->lgr;
 
+	if (!lgr)
+		return;
 	write_lock_bh(&lgr->conns_lock);
 	if (conn->alert_token_local) {
 		__smc_lgr_unregister_conn(conn);
@@ -628,6 +630,8 @@ int smc_conn_create(struct smc_sock *smc, bool is_smcd, int srv_first_contact,
 			local_contact = SMC_REUSE_CONTACT;
 			conn->lgr = lgr;
 			smc_lgr_register_conn(conn); /* add smc conn to lgr */
+			if (delayed_work_pending(&lgr->free_work))
+				cancel_delayed_work(&lgr->free_work);
 			write_unlock_bh(&lgr->conns_lock);
 			break;
 		}