Commit d5d28375 authored by David S. Miller's avatar David S. Miller
Browse files

[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: default avatarDavid S. Miller <davem@davemloft.net>
parent 89ebd197
......@@ -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
......
......@@ -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. */
......
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