Re: [PATCH -rt] Fix initialization of spinlock in irttp_dup()

[Ingo Molnar]

* Deepak Saxena [EMAIL PROTECTED] wrote:

 This was found around the 2.6.10 timeframe when testing with the -rt 
 patch and I believe is still is an issue. irttp_dup() does a memcpy() 
 of the tsap_cb structure causing the spinlock protecting various 
 fields in the structure to be duped.  This works OK in the non-RT case 
 but in the RT case we end up with two mutexes pointing to the same 
 wait_list and leading to an OOPS. Fix is to simply initialize the 
 spinlock after the memcpy().

note that memcpy based lock initialization is a problem for lockdep too.

Ingo
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[PATCH -rt] Fix initialization of spinlock in irttp_dup()

[Deepak Saxena]

This was found around the 2.6.10 timeframe when testing with the -rt patch
and I believe is still is an issue. irttp_dup() does a memcpy() of the tsap_cb 
structure causing the spinlock protecting various fields in the structure to be 
duped.  This works OK in the non-RT case but in the RT case we end up with two 
mutexes pointing to the same wait_list and leading to an OOPS. Fix is to simply
initialize the spinlock after the memcpy().

Signed-off-by: Deepak Saxena [EMAIL PROTECTED]

diff --git a/net/irda/irttp.c b/net/irda/irttp.c
index a7486b3..df2b2f7 100644
--- a/net/irda/irttp.c
+++ b/net/irda/irttp.c
@@ -1441,6 +1441,7 @@ struct tsap_cb *irttp_dup(struct tsap_cb
}
/* Dup */
memcpy(new, orig, sizeof(struct tsap_cb));
+   spin_lock_init(new-lock);
 
/* We don't need the old instance any more */
spin_unlock_irqrestore(irttp-tsaps-hb_spinlock, flags);


-- 
Deepak Saxena - [EMAIL PROTECTED] - http://www.plexity.net

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