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Commit be776281 authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

[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: default avatarEric Dumazet <dada1@cosmosbay.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 35fc92a9

net/ipv4/af_inet.c

+13 −3
Original line number Original line Diff line number Diff line
@@ -218,13 +218,23 @@ int inet_listen(struct socket *sock, int backlog) 
	return err;

	return err;

}

}





u32 inet_ehash_secret;

u32 inet_ehash_secret __read_mostly;

EXPORT_SYMBOL(inet_ehash_secret);

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)

void build_ehash_secret(void)

{

{

	while (!inet_ehash_secret)

	u32 rnd;

		get_random_bytes(&inet_ehash_secret, 4);

	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);

EXPORT_SYMBOL(build_ehash_secret);