Commit 1b5fc84a authored Nov 26, 2018 by Nicholas Piggin Committed by Michael Ellerman Feb 22, 2019

powerpc/smp: Fix NMI IPI timeout



The NMI IPI timeout logic is broken, if __smp_send_nmi_ipi() times out
on the first condition, delay_us will be zero which will send it into
the second spin loop with no timeout so it will spin forever.

Fixes: 5b73151f ("powerpc: NMI IPI make NMI IPIs fully sychronous")
Cc: stable@vger.kernel.org # v4.19+
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

parent bba43630

arch/powerpc/kernel/smp.c

+3 −2

Original line number	Diff line number	Diff line
		@@ -519,7 +519,7 @@ int __smp_send_nmi_ipi(int cpu, void (fn)(struct pt_regs ), u64 delay_us, bool
		if (delay_us) {
		delay_us--;
		if (!delay_us)
		break;
		goto timeout;
		}
		}

		@@ -530,10 +530,11 @@ int __smp_send_nmi_ipi(int cpu, void (fn)(struct pt_regs ), u64 delay_us, bool
		if (delay_us) {
		delay_us--;
		if (!delay_us)
		break;
		goto timeout;
		}
		}

		timeout:
		if (!cpumask_empty(&nmi_ipi_pending_mask)) {
		/* Timeout waiting for CPUs to call smp_handle_nmi_ipi */
		ret = 0;