Commit 6bed3237 authored Apr 01, 2018 by Nicholas Piggin Committed by Michael Ellerman Apr 03, 2018

powerpc: use NMI IPI for smp_send_stop



Use the NMI IPI rather than smp_call_function for smp_send_stop.
Have stopped CPUs hard disable interrupts rather than just soft
disable.

This function is used in crash/panic/shutdown paths to bring other
CPUs down as quickly and reliably as possible, and minimizing their
potential to cause trouble.

Avoiding the Linux smp_call_function infrastructure and (if supported)
using true NMI IPIs makes this more robust.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

parent a2b5e056

arch/powerpc/kernel/smp.c

+8 −0

Original line number	Diff line number	Diff line
		@@ -565,7 +565,11 @@ void crash_send_ipi(void (crash_ipi_callback)(struct pt_regs ))
		}
		#endif

		#ifdef CONFIG_NMI_IPI
		static void stop_this_cpu(struct pt_regs *regs)
		#else
		static void stop_this_cpu(void *dummy)
		#endif
		{
		/* Remove this CPU */
		set_cpu_online(smp_processor_id(), false);
		@@ -577,7 +581,11 @@ static void stop_this_cpu(void *dummy)

		void smp_send_stop(void)
		{
		#ifdef CONFIG_NMI_IPI
		smp_send_nmi_ipi(NMI_IPI_ALL_OTHERS, stop_this_cpu, 1000000);
		#else
		smp_call_function(stop_this_cpu, NULL, 0);
		#endif
		}

		struct thread_info *current_set[NR_CPUS];