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authorDavid S. Miller <davem@davemloft.net>2005-08-23 13:49:54 -0400
committerDavid S. Miller <davem@davemloft.net>2005-08-23 13:49:54 -0400
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 5d91213d34c0..67c670886c1f 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)
242 tcp_port_rover = rover; 242 tcp_port_rover = rover;
243 spin_unlock(&tcp_portalloc_lock); 243 spin_unlock(&tcp_portalloc_lock);
244 244
245 /* Exhausted local port range during search? */ 245 /* Exhausted local port range during search? It is not
246 * possible for us to be holding one of the bind hash
247 * locks if this test triggers, because if 'remaining'
248 * drops to zero, we broke out of the do/while loop at
249 * the top level, not from the 'break;' statement.
250 */
246 ret = 1; 251 ret = 1;
247 if (remaining <= 0) 252 if (unlikely(remaining <= 0))
248 goto fail; 253 goto fail;
249 254
250 /* OK, here is the one we will use. HEAD is 255 /* 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 f6e288dc116e..ef29cfd936d3 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)
158 tcp_port_rover = rover; 158 tcp_port_rover = rover;
159 spin_unlock(&tcp_portalloc_lock); 159 spin_unlock(&tcp_portalloc_lock);
160 160
161 /* Exhausted local port range during search? */ 161 /* Exhausted local port range during search? It is not
162 * possible for us to be holding one of the bind hash
163 * locks if this test triggers, because if 'remaining'
164 * drops to zero, we broke out of the do/while loop at
165 * the top level, not from the 'break;' statement.
166 */
162 ret = 1; 167 ret = 1;
163 if (remaining <= 0) 168 if (unlikely(remaining <= 0))
164 goto fail; 169 goto fail;
165 170
166 /* OK, here is the one we will use. */ 171 /* OK, here is the one we will use. */