5.0-stable review patch. If anyone has any objections, please let me know.
------------------
From: Nicholas Piggin <npiggin@xxxxxxxxx>
commit 1b5fc84aba170bdfe3533396ca9662ceea1609b7 upstream.
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@xxxxxxxxxxxxxxx # v4.19+
Signed-off-by: Nicholas Piggin <npiggin@xxxxxxxxx>
Signed-off-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/powerpc/kernel/smp.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
--- a/arch/powerpc/kernel/smp.c
+++ b/arch/powerpc/kernel/smp.c
@@ -519,7 +519,7 @@ int __smp_send_nmi_ipi(int cpu, void (*f
if (delay_us) {
delay_us--;
if (!delay_us)
- break;
+ goto timeout;
}
}
@@ -530,10 +530,11 @@ int __smp_send_nmi_ipi(int cpu, void (*f
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;
