From 96ea91e7b6ee2c406598d859e7348b4829404eea Mon Sep 17 00:00:00 2001 From: Nicholas Piggin Date: Wed, 9 Aug 2017 22:41:26 +1000 Subject: [PATCH] powerpc/watchdog: add locking around init/exit functions When CPUs start and stop the watchdog, they manipulate shared data that is normally protected by the lock. Other CPUs can be running concurrently at this time, so it's a good idea to use locking here to be on the safe side. Remove the barrier which is undocumented and didn't do anything. Signed-off-by: Nicholas Piggin Signed-off-by: Michael Ellerman --- arch/powerpc/kernel/watchdog.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) diff --git a/arch/powerpc/kernel/watchdog.c b/arch/powerpc/kernel/watchdog.c index 12e90ae712fe..34721a257a77 100644 --- a/arch/powerpc/kernel/watchdog.c +++ b/arch/powerpc/kernel/watchdog.c @@ -297,6 +297,8 @@ static void stop_watchdog_timer_on(unsigned int cpu) static int start_wd_on_cpu(unsigned int cpu) { + unsigned long flags; + if (cpumask_test_cpu(cpu, &wd_cpus_enabled)) { WARN_ON(1); return 0; @@ -311,12 +313,14 @@ static int start_wd_on_cpu(unsigned int cpu) if (!cpumask_test_cpu(cpu, &watchdog_cpumask)) return 0; + wd_smp_lock(&flags); cpumask_set_cpu(cpu, &wd_cpus_enabled); if (cpumask_weight(&wd_cpus_enabled) == 1) { cpumask_set_cpu(cpu, &wd_smp_cpus_pending); wd_smp_last_reset_tb = get_tb(); } - smp_wmb(); + wd_smp_unlock(&flags); + start_watchdog_timer_on(cpu); return 0; @@ -324,12 +328,17 @@ static int start_wd_on_cpu(unsigned int cpu) static int stop_wd_on_cpu(unsigned int cpu) { + unsigned long flags; + if (!cpumask_test_cpu(cpu, &wd_cpus_enabled)) return 0; /* Can happen in CPU unplug case */ stop_watchdog_timer_on(cpu); + wd_smp_lock(&flags); cpumask_clear_cpu(cpu, &wd_cpus_enabled); + wd_smp_unlock(&flags); + wd_smp_clear_cpu_pending(cpu, get_tb()); return 0; -- 2.39.2