Messages in this thread | | | From | Seiji Aguchi <> | Date | Tue, 19 Jul 2011 15:14:22 -0400 | Subject | RE: [RFC][PATCH -mmotm 1/4] Add static function calls of pstore to kexec path |
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>And how does that handle the case where we're halfway through a pstore >access when the NMI arrives? ERST, at least, has a complex state >machine. You can't guarantee what starting one transaction without >completing one that was in process will do.
As for ERST, write access is protected by raw_spin_trylock_irqsave(&erst_lock). Are there anything I'm missing?
Seiji
>-----Original Message----- >From: Matthew Garrett [mailto:mjg@redhat.com] >Sent: Tuesday, July 19, 2011 2:52 PM >To: Seiji Aguchi >Cc: kexec@lists.infradead.org; linux-kernel@vger.kernel.org; linux-mtd@lists.infradead.org; Eric W. Biederman; Vivek >Goyal; KOSAKI Motohiro; Americo Wang; tony.luck@intel.com; Andrew Morton; Jarod Wilson; hpa@zytor.com; dzickus@redhat.com; >dle-develop@lists.sourceforge.net; Satoru Moriya >Subject: Re: [RFC][PATCH -mmotm 1/4] Add static function calls of pstore to kexec path > >On Tue, Jul 19, 2011 at 02:48:22PM -0400, Seiji Aguchi wrote: >> >How is this safe? What happens if there's a pstore access in process >> >when you hit this codepath? >> >> This will never happen because pstore_kmsg_dump_in_interrupt() is called after machine_crash_shutdown(). >> >> Panicked cpu sends NMI to all other cpus in machine_crash_shutdown() and they stop. > >And how does that handle the case where we're halfway through a pstore >access when the NMI arrives? ERST, at least, has a complex state >machine. You can't guarantee what starting one transaction without >completing one that was in process will do. > >-- >Matthew Garrett | mjg59@srcf.ucam.org
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