Messages in this thread | ![/](/images/icornerl.gif) | | Date | Sat, 21 Apr 2001 16:29:26 +0200 | From | Andrea Arcangeli <> | Subject | Re: x86 rwsem in 2.4.4pre[234] are still buggy [was Re: rwsem benchmarks [Re: generic rwsem [Re: Alpha "process table hang"]]] |
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On Sat, Apr 21, 2001 at 03:17:37PM +0100, Russell King wrote: > On Sat, Apr 21, 2001 at 04:03:27PM +0200, Andrea Arcangeli wrote: > > On Fri, Apr 20, 2001 at 04:45:32PM -0700, Linus Torvalds wrote: > > > I would suggest the following: > > > > > > - the generic semaphores should use the lock that already exists in the > > > wait-queue as the semaphore spinlock. > > > > Ok, that is what my generic code does. > > Erm, spin_lock()? What if up_read or up_write gets called from interrupt > context (is this allowed)?
That it is allowed by my generic code that does spin_lock_irq in down_* and spin_lock_irqsave in up_* but it's disallowed by the weaker semantics of the generic and x86 semaphores 2.4.4pre[2345] (or + David's last patch).
> If these are now allowed, then maybe we should either consider getting > the Stanford checker to check for this, or else we ought to do a debugging > if (in_interupt()) BUG(); thing.
Caller bug is the last of my worries. (and I seriously doubt that if somebody doesn't know the semantics of the rwsem, he will care to enable the debugging checks during regression testing ;)
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