On Mon, 2013-10-07 at 21:37 -0700, Hugh Dickins wrote:
> Phew, I was gearing up to sending you a report on how Frederic's
> "low-risk" irq stack patch had broken booting -rc4 on the G5 Quad;
> but noticed this just gone in, gave it a try, it fixes it.
>
> (I see Frederic's ded797547548 is marked for stable,
> perhaps you'll have to chase that one with this.)
Good point, this should go into stable at the same time. Thanks !
Stable folks, the commit below
(8b5ede69d24db939f52b47effff2f6fe1e83e08b) is in Linus tree and should
hit the same stable trees as Fred's ded797547548 if possible. Thanks !
Cheers,
Ben.
> Hugh
>
> commit 8b5ede69d24db939f52b47effff2f6fe1e83e08b
> Author: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
> Date: Tue Oct 8 08:08:24 2013 +1100
>
> powerpc/irq: Don't switch to irq stack from softirq stack
>
> irq_exit() is now called on the irq stack, which can trigger a switch to
> the softirq stack from the irq stack. If an interrupt happens at that
> point, we will not properly detect the re-entrancy and clobber the
> original return context on the irq stack.
>
> This fixes it. The side effect is to prevent all nesting from softirq
> stack to irq stack even in the "safe" case but it's simpler that way and
> matches what x86_64 does.
>
> Reported-by: Cedric Le Goater <clg@xxxxxxxxxx>
> Tested-by: Cedric Le Goater <clg@xxxxxxxxxx>
> Signed-off-by: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
> Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
>
> diff --git a/arch/powerpc/kernel/irq.c b/arch/powerpc/kernel/irq.c
> index 57d286a..c7cb8c2 100644
> --- a/arch/powerpc/kernel/irq.c
> +++ b/arch/powerpc/kernel/irq.c
> @@ -495,14 +495,15 @@ void __do_irq(struct pt_regs *regs)
> void do_IRQ(struct pt_regs *regs)
> {
> struct pt_regs *old_regs = set_irq_regs(regs);
> - struct thread_info *curtp, *irqtp;
> + struct thread_info *curtp, *irqtp, *sirqtp;
>
> /* Switch to the irq stack to handle this */
> curtp = current_thread_info();
> irqtp = hardirq_ctx[raw_smp_processor_id()];
> + sirqtp = softirq_ctx[raw_smp_processor_id()];
>
> /* Already there ? */
> - if (unlikely(curtp == irqtp)) {
> + if (unlikely(curtp == irqtp || curtp == sirqtp)) {
> __do_irq(regs);
> set_irq_regs(old_regs);
> return;
--
To unsubscribe from this list: send the line "unsubscribe stable" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html