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authorDavid S. Miller <davem@davemloft.net>2005-08-23 10:49:54 -0700
committerDavid S. Miller <davem@davemloft.net>2005-08-23 10:49:54 -0700
commitd5d283751ef3c05b6766501a46800cbee84959d6 (patch)
treec8de7a2dbd69efb233f1b051bdfceed7eded379a
parent89ebd197eb2cd31d6187db344d5117064e19fdde (diff)
[TCP]: Document non-trivial locking path in tcp_v{4,6}_get_port().
This trips up a lot of folks reading this code. Put an unlikely() around the port-exhaustion test for good measure. Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r--net/ipv4/tcp_ipv4.c9
-rw-r--r--net/ipv6/tcp_ipv6.c9
2 files changed, 14 insertions, 4 deletions
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 5d91213d34c..67c670886c1 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -242,9 +242,14 @@ static int tcp_v4_get_port(struct sock *sk, unsigned short snum)
tcp_port_rover = rover;
spin_unlock(&tcp_portalloc_lock);
- /* Exhausted local port range during search? */
+ /* Exhausted local port range during search? It is not
+ * possible for us to be holding one of the bind hash
+ * locks if this test triggers, because if 'remaining'
+ * drops to zero, we broke out of the do/while loop at
+ * the top level, not from the 'break;' statement.
+ */
ret = 1;
- if (remaining <= 0)
+ if (unlikely(remaining <= 0))
goto fail;
/* OK, here is the one we will use. HEAD is
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index f6e288dc116..ef29cfd936d 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -158,9 +158,14 @@ static int tcp_v6_get_port(struct sock *sk, unsigned short snum)
tcp_port_rover = rover;
spin_unlock(&tcp_portalloc_lock);
- /* Exhausted local port range during search? */
+ /* Exhausted local port range during search? It is not
+ * possible for us to be holding one of the bind hash
+ * locks if this test triggers, because if 'remaining'
+ * drops to zero, we broke out of the do/while loop at
+ * the top level, not from the 'break;' statement.
+ */
ret = 1;
- if (remaining <= 0)
+ if (unlikely(remaining <= 0))
goto fail;
/* OK, here is the one we will use. */