powerpc/smp: Fix NMI IPI timeout

[ Upstream commit 1b5fc84aba170bdfe3533396ca9662ceea1609b7 ]

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: 5b73151fff63 ("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>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>

diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c
index 61c1fad..22abba5 100644 (file)
--- a/arch/powerpc/kernel/smp.c
+++ b/arch/powerpc/kernel/smp.c
@@ -499,7 +499,7 @@ 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;
                }
        }
 
@@ -510,10 +510,11 @@ 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;