Messages in this thread Patch in this message | | | Subject | Re: [patch] irqlock patch -G3. [was Re: odd memory corruption in 2.5.27?] | From | Robert Love <> | Date | 23 Jul 2002 18:08:17 -0700 |
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On Tue, 2002-07-23 at 16:28, Ingo Molnar wrote:
> this is most definitely not the correct fix ... > > i'm quite convinced that the fix is to avoid illegal preemption, not to > work it around.
I am not sure I am fully convinced one way or the other, but treating every bit of code as we find it scares me. The fact is, if a spin_unlock() can magically reenable interrupts that is a bug.
I don't like relying on chance and the possibility your debug tool found the problem... but at the same time, Ingo's solution is a lot cleaner.
Linus, Ingo, comments?
Attached is the patch George mentioned, against 2.5.27.
Robert Love
diff -urN linux-2.5.27/include/asm-i386/system.h linux/include/asm-i386/system.h --- linux-2.5.27/include/asm-i386/system.h Sat Jul 20 12:11:05 2002 +++ linux/include/asm-i386/system.h Tue Jul 23 18:03:47 2002 @@ -270,6 +270,13 @@ /* Compiling for a 386 proper. Is it worth implementing via cli/sti? */ #endif +#define MASK_IF 0x200 +#define interrupts_enabled() ({ \ + int flg; \ + __save_flags(flg); \ + flg & MASK_IF; \ +}) + /* * Force strict CPU ordering. * And yes, this is required on UP too when we're talking diff -urN linux-2.5.27/kernel/sched.c linux/kernel/sched.c --- linux-2.5.27/kernel/sched.c Sat Jul 20 12:11:11 2002 +++ linux/kernel/sched.c Tue Jul 23 18:02:13 2002 @@ -899,7 +899,7 @@ { struct thread_info *ti = current_thread_info(); - if (unlikely(ti->preempt_count)) + if (unlikely(ti->preempt_count || !interrupts_enabled())) return; need_resched: - 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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