Messages in this thread | | | Date | Tue, 04 Dec 2001 13:25:40 -0800 | From | george anzinger <> | Subject | Re: [PATCH] improve spinlock debugging |
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Robert Love wrote: > > On Tue, 2001-12-04 at 15:30, george anzinger wrote: > > > spin_lockirq > > > > spin_unlock > > > > restore_irq > > Given this order, couldn't we _always_ not touch the preempt count since > irq's are off? > > Further, since I doubt we ever see: > > spin_lock_irq > restore_irq > spin_unlock > > and the common use is: > > spin_lock_irq > spin_unlock_irq > > Isn't it safe to have spin_lock_irq *never* touch the preempt count? > NO. The problem is the first example above. The spin_unlock will down count, but the spin_lockirq did NOT do the paired up count (been there, done that). This is where we need the spin_unlock_no_irq_restore. -- George george@mvista.com High-res-timers: http://sourceforge.net/projects/high-res-timers/ Real time sched: http://sourceforge.net/projects/rtsched/ - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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