Re: [patch] Real-Time Preemption, -RT-2.6.9-mm1-V0.6.8

[Ingo Molnar]

* Ingo Molnar <mingo@xxxxxxx> wrote:

> yeah, this is yet another networking deadlock, nicely detected and
> logged. Since the deadlock locks up ksoftirqd, timer handling (also
> driven by ksoftirqd) wont work - i think this explains the followup
> symptoms you got.

the patch below should fix this deadlock but there might be others
around ...

	Ingo

--- linux/include/net/sock.h.orig2	
+++ linux/include/net/sock.h	
@@ -706,8 +706,8 @@ extern void FASTCALL(lock_sock(struct so
 extern void FASTCALL(release_sock(struct sock *sk));
 
 /* BH context may only use the following locking interface. */
-#define bh_lock_sock(__sk)	spin_lock(&((__sk)->sk_lock.slock))
-#define bh_unlock_sock(__sk)	spin_unlock(&((__sk)->sk_lock.slock))
+#define bh_lock_sock(__sk)	do { rcu_read_lock_read(&ptype_lock); spin_lock(&((__sk)->sk_lock.slock)); } while (0)
+#define bh_unlock_sock(__sk)	do { spin_unlock(&((__sk)->sk_lock.slock)); rcu_read_unlock_read(&ptype_lock); } while (0)
 
 extern struct sock *		sk_alloc(int family, int priority, int zero_it,
 					 kmem_cache_t *slab);
-
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