From: Nicholas Piggin Date: Thu, 25 Nov 2021 10:33:46 +0000 (+1000) Subject: powerpc/watchdog: Fix wd_smp_last_reset_tb reporting X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=3d030e301856da366380b3865fce6c03037b08a6;p=linux.git powerpc/watchdog: Fix wd_smp_last_reset_tb reporting wd_smp_last_reset_tb now gets reset by watchdog_smp_panic() as part of marking CPUs stuck and removing them from the pending mask before it begins any printing. This causes last reset times reported to be off. Fix this by reading it into a local variable before it gets reset. Fixes: 76521c4b0291 ("powerpc/watchdog: Avoid holding wd_smp_lock over printk and smp_send_nmi_ipi") Signed-off-by: Nicholas Piggin Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20211125103346.1188958-1-npiggin@gmail.com --- diff --git a/arch/powerpc/kernel/watchdog.c b/arch/powerpc/kernel/watchdog.c index b6533539386b4..23745af38d62c 100644 --- a/arch/powerpc/kernel/watchdog.c +++ b/arch/powerpc/kernel/watchdog.c @@ -179,13 +179,14 @@ static void watchdog_smp_panic(int cpu) { static cpumask_t wd_smp_cpus_ipi; // protected by reporting unsigned long flags; - u64 tb; + u64 tb, last_reset; int c; wd_smp_lock(&flags); /* Double check some things under lock */ tb = get_tb(); - if ((s64)(tb - wd_smp_last_reset_tb) < (s64)wd_smp_panic_timeout_tb) + last_reset = wd_smp_last_reset_tb; + if ((s64)(tb - last_reset) < (s64)wd_smp_panic_timeout_tb) goto out; if (cpumask_test_cpu(cpu, &wd_smp_cpus_pending)) goto out; @@ -210,8 +211,7 @@ static void watchdog_smp_panic(int cpu) pr_emerg("CPU %d detected hard LOCKUP on other CPUs %*pbl\n", cpu, cpumask_pr_args(&wd_smp_cpus_ipi)); pr_emerg("CPU %d TB:%lld, last SMP heartbeat TB:%lld (%lldms ago)\n", - cpu, tb, wd_smp_last_reset_tb, - tb_to_ns(tb - wd_smp_last_reset_tb) / 1000000); + cpu, tb, last_reset, tb_to_ns(tb - last_reset) / 1000000); if (!sysctl_hardlockup_all_cpu_backtrace) { /*