Re: [PATCH] little schedule() cleanup: use cached current value
From: Ingo Molnar
Date: Tue Nov 09 2004 - 06:46:10 EST
* Oleg Nesterov <oleg@xxxxxxxxxx> wrote:
> @@ -2636,7 +2636,7 @@ switch_tasks:
> } else
> - reacquire_kernel_lock(current);
> + reacquire_kernel_lock(next);
> if (unlikely(test_thread_flag(TIF_NEED_RESCHED)))
> goto need_resched;
nack. We switch the kernel stack in switch_to() so 'next' here is the
old task we switched to before we went off the CPU. The value of 'next'
doesnt get carried over a context-switch. (we do carry 'prev' over via
assembly trickery because we need it, but not 'next'.) This change would
most likely result in rare, hard-to-track-down BKL-related crashes all
around the place.
the other bits are OK, please resend them.
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/