Messages in this thread | | | Subject | Re: [PATCH] sysrq : fix Show Regs call trace on ARM | From | Jiri Slaby <> | Date | Wed, 13 Sep 2017 08:14:30 +0200 |
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On 09/13/2017, 08:04 AM, Jiri Slaby wrote: > On 09/11/2017, 01:22 PM, Jibin Xu wrote: >> Hi,Jiri: >> >> I tested get_irq_regs() behave in the softirq context, >> I called get_irq_regs() by a tasklet, It returns NULL.My understanding is get_irq_regs() can return the right result >> only in hardware IRQ,otherwise it returns NULL. >> So I think in_irq() would be better. > > Hi, > > tasklets are run in the process context (in a kthread). But what about > timers? HARDIRQ is decremented, SOFTIRQ remains set and sysrq handlers > are called in such conditions (in_interrupt() is true, in_irq() is > false). At that moment, irq_regs are still set and valid IMO. > > But I would believe for now that sysrq handlers are not invoked from > softirq context. AFAIK they are called only from hardirq (serial port or > keyboard IRQ handler) or process context (write to /proc/sysrq-trigger). > So this change *should* be safe unless someone else objects there are > some kgdb special cases or something.
Oops, serial8250_timeout actually can do so. So yes, sysrq handlers can be invoked from softirq (timer) context and they still should print the registers at best.
I have to leave now, will look into it later if someone (you :)) doesn't beat me to it.
thanks, -- js suse labs
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