Hello,
At Thu, 02 Aug 2001 13:44:24 -0400,
Brent Baccala wrote:
>
> No longer any race (right?) and we don't lose anything since the one
> processor is about to drop the lock it (presumably) held. I wonder if
> it should check to make sure the same processor that grabbed the lock is
> releasing it. Not exactly a bug, and somebody might write code like
> that, but it seems suspicious. Comments?
last_lock_processor should be initialized as -1, or you have another
race.
cpu0 cpu1
----------------------------------------------------------------------------------------
last_lock_processor is 0
call spin_unlock...
asm(spin_lock_string)
call spin_lock...
if (spin_is_locked(lock)
&& lock->last_lock_processor == my_processor_id)
-------------------------------------------
last_lock_processor and my_processor_id are
both 0 here. So BUG() is called incorrectly.
-------------------------------------------
asm(spin_lock_string)
last_lock_processor = 1;
-
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This archive was generated by hypermail 2b29 : Tue Aug 07 2001 - 21:00:25 EST