From: "Leigh Brown" <[EMAIL PROTECTED]> Date: Sun, 17 Dec 2006 18:13:06 -0000 (GMT)
> It was all going so well, and then it deadlocked. What can be done > about this? Sorry for taking so long about this. The problem is that tcp_md5sig_pool_lock is taken in both software-interrupt and non-software-interrupt contexts, but it is always acquired/released using spin_lock/spin_unlock. The most conservative fix, which I'll use for 2.6.21 and 2.6.x-stable, is the following. I invite anyone to rewrite this md5 signature pool mutual exclusion code, it's not exactly the best :-) Thanks for reporting this problem. diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index ac6516c..74c4d10 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -2266,12 +2266,12 @@ void tcp_free_md5sig_pool(void) { struct tcp_md5sig_pool **pool = NULL; - spin_lock(&tcp_md5sig_pool_lock); + spin_lock_bh(&tcp_md5sig_pool_lock); if (--tcp_md5sig_users == 0) { pool = tcp_md5sig_pool; tcp_md5sig_pool = NULL; } - spin_unlock(&tcp_md5sig_pool_lock); + spin_unlock_bh(&tcp_md5sig_pool_lock); if (pool) __tcp_free_md5sig_pool(pool); } @@ -2314,36 +2314,36 @@ struct tcp_md5sig_pool **tcp_alloc_md5sig_pool(void) int alloc = 0; retry: - spin_lock(&tcp_md5sig_pool_lock); + spin_lock_bh(&tcp_md5sig_pool_lock); pool = tcp_md5sig_pool; if (tcp_md5sig_users++ == 0) { alloc = 1; - spin_unlock(&tcp_md5sig_pool_lock); + spin_unlock_bh(&tcp_md5sig_pool_lock); } else if (!pool) { tcp_md5sig_users--; - spin_unlock(&tcp_md5sig_pool_lock); + spin_unlock_bh(&tcp_md5sig_pool_lock); cpu_relax(); goto retry; } else - spin_unlock(&tcp_md5sig_pool_lock); + spin_unlock_bh(&tcp_md5sig_pool_lock); if (alloc) { /* we cannot hold spinlock here because this may sleep. */ struct tcp_md5sig_pool **p = __tcp_alloc_md5sig_pool(); - spin_lock(&tcp_md5sig_pool_lock); + spin_lock_bh(&tcp_md5sig_pool_lock); if (!p) { tcp_md5sig_users--; - spin_unlock(&tcp_md5sig_pool_lock); + spin_unlock_bh(&tcp_md5sig_pool_lock); return NULL; } pool = tcp_md5sig_pool; if (pool) { /* oops, it has already been assigned. */ - spin_unlock(&tcp_md5sig_pool_lock); + spin_unlock_bh(&tcp_md5sig_pool_lock); __tcp_free_md5sig_pool(p); } else { tcp_md5sig_pool = pool = p; - spin_unlock(&tcp_md5sig_pool_lock); + spin_unlock_bh(&tcp_md5sig_pool_lock); } } return pool; @@ -2354,11 +2354,11 @@ EXPORT_SYMBOL(tcp_alloc_md5sig_pool); struct tcp_md5sig_pool *__tcp_get_md5sig_pool(int cpu) { struct tcp_md5sig_pool **p; - spin_lock(&tcp_md5sig_pool_lock); + spin_lock_bh(&tcp_md5sig_pool_lock); p = tcp_md5sig_pool; if (p) tcp_md5sig_users++; - spin_unlock(&tcp_md5sig_pool_lock); + spin_unlock_bh(&tcp_md5sig_pool_lock); return (p ? *per_cpu_ptr(p, cpu) : NULL); } - To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html