Messages in this thread | | | Date | Wed, 17 Nov 2004 12:46:40 -0800 | From | Andrew Morton <> | Subject | Re: 2.6.10-rc2-mm1 - detect-atomic-counter-underflows.patch |
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Valdis.Kletnieks@vt.edu wrote: > > Now, I *may* have simply shot myself in the foot, but when I tried booting > 2.6.10-rc2-mm1, I got spewed *thousands* of messages triggered by this: > > diff -puN include/asm-i386/atomic.h~detect-atomic-counter-underflows include/asm-i386/atomic.h > --- 25/include/asm-i386/atomic.h~detect-atomic-counter-underflows Wed Nov 3 15:27:37 2004 > +++ 25-akpm/include/asm-i386/atomic.h Wed Nov 3 15:27:37 2004 > @@ -132,6 +132,10 @@ static __inline__ int atomic_dec_and_tes > { > unsigned char c; > > + if (!atomic_read(v)) { > + printk("BUG: atomic counter underflow at:\n"); > + dump_stack(); > + } > __asm__ __volatile__( > LOCK "decl %0; sete %1" > :"=m" (v->counter), "=qm" (c) > > Somehow, warning a *counter* is non-zero doesn't seem right (calling it an > underflow 4 times if the value goes 4, 3, 2, 1 and then NOT complain when it > hits zero?) , and I'm not flooded if it says: > > if (atomic_read(v) < 0) {
No, the code is OK. It's telling us that we're about to take the counter negative, and that's a good predictor of a bug somewhere.
> So is this code wrong, or did I introduce an now-detected underflow with some > self-inflicted patch that this is picking up?
Dunno. What was in the traces? - 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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