diff options
| author | Eric Dumazet <dada1@cosmosbay.com> | 2007-03-27 22:53:04 +0200 |
|---|---|---|
| committer | David S. Miller <davem@sunset.davemloft.net> | 2007-04-26 07:28:17 +0200 |
| commit | be776281aee54626a474ba06f91926b98bdd180d (patch) | |
| tree | 7f397daec3c52ca04267186450f290f5e0ea3c5f | |
| parent | [NET]: Allow forwarding of ip_summed except CHECKSUM_COMPLETE (diff) | |
| download | linux-be776281aee54626a474ba06f91926b98bdd180d.tar.xz linux-be776281aee54626a474ba06f91926b98bdd180d.zip | |
[NET]: inet_ehash_secret should be __read_mostly and set only once
There is a very tiny probability that build_ehash_secret() is called
at the same time by different CPUS.
Also, using __read_mostly is a must for inet_ehash_secret
Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
| -rw-r--r-- | net/ipv4/af_inet.c | 16 |
1 files changed, 13 insertions, 3 deletions
diff --git a/net/ipv4/af_inet.c b/net/ipv4/af_inet.c index b7b7278d801c..45ced52c03d4 100644 --- a/net/ipv4/af_inet.c +++ b/net/ipv4/af_inet.c @@ -218,13 +218,23 @@ out: return err; } -u32 inet_ehash_secret; +u32 inet_ehash_secret __read_mostly; EXPORT_SYMBOL(inet_ehash_secret); +/* + * inet_ehash_secret must be set exactly once + * Instead of using a dedicated spinlock, we (ab)use inetsw_lock + */ void build_ehash_secret(void) { - while (!inet_ehash_secret) - get_random_bytes(&inet_ehash_secret, 4); + u32 rnd; + do { + get_random_bytes(&rnd, sizeof(rnd)); + } while (rnd == 0); + spin_lock_bh(&inetsw_lock); + if (!inet_ehash_secret) + inet_ehash_secret = rnd; + spin_unlock_bh(&inetsw_lock); } EXPORT_SYMBOL(build_ehash_secret); |