Re: [PATCH] kprobes: fix race in aggregate kprobe registration

[Keshavamurthy Anil S]

On Tue, Dec 06, 2005 at 10:47:11AM +0530, Ananth N Mavinakayanahalli wrote:
> From: Ananth N Mavinakayanahalli <ananth@xxxxxxxxxx>
> 
> When registering multiple kprobes at the same address, we leave a small
> window where the kprobe hlist will not contain a reference to the
> registered kprobe, leading to potentially, a system crash if the
> breakpoint is hit on another processor.
> 
> Patch below changes the order of hlist updation to make sure that there
> is always a reference to the kprobe at the location.

Hi Ananth,
	How do you like this patch? Here the old entry
will be replace with the new entry automically. 

Signed-off-by: Anil S Keshavamurthy <anil.s.keshavamurthy@xxxxxxxxx>

 kernel/kprobes.c |    5 +----
 1 files changed, 1 insertion(+), 4 deletions(-)

Index: linux-2.6.15-rc5-mm1/kernel/kprobes.c
===================================================================
--- linux-2.6.15-rc5-mm1.orig/kernel/kprobes.c
+++ linux-2.6.15-rc5-mm1/kernel/kprobes.c
@@ -399,10 +399,7 @@ static inline void add_aggr_kprobe(struc
 	INIT_LIST_HEAD(&ap->list);
 	list_add_rcu(&p->list, &ap->list);
 
-	INIT_HLIST_NODE(&ap->hlist);
-	hlist_del_rcu(&p->hlist);
-	hlist_add_head_rcu(&ap->hlist,
-		&kprobe_table[hash_ptr(ap->addr, KPROBE_HASH_BITS)]);
+	hlist_replace_rcu(&p->hlist, &ap->hlist);
 }
 
 /*
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/