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[NET]: inet_ehash_secret should be __read_mostly and set only once

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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>
This commit is contained in:
Eric Dumazet 2007-03-27 13:53:04 -07:00 committed by David S. Miller
parent 35fc92a9de
commit be776281ae
1 changed files with 13 additions and 3 deletions
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16
net/ipv4/af_inet.c
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@ -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);