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[TCP]: Document non-trivial locking path in tcp_v{4,6}_get_port().

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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>
This commit is contained in:
David S. Miller 2005-08-23 10:49:54 -07:00
parent 89ebd197eb
commit d5d283751e
2 changed files with 14 additions and 4 deletions
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9
net/ipv4/tcp_ipv4.c
View File

@ -242,9 +242,14 @@ static int tcp_v4_get_port(struct sock *sk, unsigned short snum)
tcp_port_rover = rover; tcp_port_rover = rover;
spin_unlock(&tcp_portalloc_lock); 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; ret = 1;
if (remaining <= 0) if (unlikely(remaining <= 0))
goto fail; goto fail;
/* OK, here is the one we will use. HEAD is /* OK, here is the one we will use. HEAD is

9
net/ipv6/tcp_ipv6.c
View File

@ -158,9 +158,14 @@ static int tcp_v6_get_port(struct sock *sk, unsigned short snum)
tcp_port_rover = rover; tcp_port_rover = rover;
spin_unlock(&tcp_portalloc_lock); 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; ret = 1;
if (remaining <= 0) if (unlikely(remaining <= 0))
goto fail; goto fail;
/* OK, here is the one we will use. */ /* OK, here is the one we will use. */