Messages in this thread | | | Date | Tue, 15 Sep 2015 12:30:03 +0100 | From | Russell King - ARM Linux <> | Subject | Re: [PATCH v2] arm: Fix backtrace generation when IPI is masked |
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On Tue, Sep 15, 2015 at 12:05:12PM +0100, Daniel Thompson wrote: > Currently on ARM when <SysRq-L> is triggered from an interrupt handler > (e.g. a SysRq issued using UART or kbd) the main CPU will wedge for ten > seconds with interrupts masked before issuing a backtrace for every CPU > except itself. > > The new backtrace code introduced by commit 96f0e00378d4 ("ARM: add > basic support for on-demand backtrace of other CPUs") does not work > correctly when run from an interrupt handler because IPI_CPU_BACKTRACE > is used to generate the backtrace on all CPUs but cannot preempt the > current calling context.
This patch needs a little more work - what happens to the IPI_CPU_BACKTRACE we've sent to ourselves? (It fires after the interrupt handler for the UART/kbd has finished.) It ought to be masked out if we're going to handle it a different way.
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