Re: [PATCH] RT: Checks for cmpxchg in get_task_struct_rcu()
From: Nick Piggin
Date: Thu Sep 22 2005 - 00:05:05 EST
Daniel Walker wrote:
+#else
+ raw_local_irq_disable();
+ oldusage = atomic_read(&t->usage);
+ if (oldusage == 0) {
+ raw_local_irq_enable();
+ return 0;
+ }
Isn't this still racy if another cpu drops the last reference
to task struct here? Or can't that happen?
When you said "disable preempt", I had some silly idea that this
function was only used in PREEMPT_RT mode, and that you would
simply disallow architectures without cmpxchg from configuring
PREEMPT_RT.
+ atomic_inc(&t->usage);
+ raw_local_irq_enable();
+#endif
--
SUSE Labs, Novell Inc.
Send instant messages to your online friends http://au.messenger.yahoo.com
-
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/