Messages in this thread | | | Subject | Re: [PATCH 1/1] powerpc/crash: Use NMI context for printk after crashing other CPUs | From | Leonardo Bras <> | Date | Wed, 08 Apr 2020 15:41:37 -0300 |
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On Wed, 2020-04-08 at 22:13 +1000, Michael Ellerman wrote: [...] > Added context: > > printk(KERN_EMERG "Sending IPI to other CPUs\n"); > > if (crash_wake_offline) > ncpus = num_present_cpus() - 1; > > > > > crash_send_ipi(crash_ipi_callback); > > smp_wmb(); > > + printk_nmi_enter(); > > Why did you decide to put it there, rather than at the start of > default_machine_crash_shutdown() like I did? > > The printk() above could have already deadlocked if another CPU is stuck > with the logbuf lock held.
Oh, I thought the CPUs would start crashing after crash_send_ipi(), so only printk() after that would possibly deadlock.
I was not able to see how the printk() above would deadlock, but I see no problem adding that at the start of the function.
Best regards, Leonardo Bras [unhandled content-type:application/pgp-signature] | |