[PATCH v2] powerpc/watchdog: Use hrtimers for per-CPU heartbeat

[Ravi Bangoria]

On 4/9/19 10:10 AM, Nicholas Piggin wrote:
> Using a jiffies timer creates a dependency on the tick_do_timer_cpu
> incrementing jiffies. If that CPU has locked up and jiffies is not
> incrementing, the watchdog heartbeat timer for all CPUs stops and
> creates false positives and confusing warnings on local CPUs, and
> also causes the SMP detector to stop, so the root cause is never
> detected.
> 
> Fix this by using hrtimer based timers for the watchdog heartbeat,
> like the generic kernel hardlockup detector.
> 
> Cc: Gautham R. Shenoy <ego at linux.vnet.ibm.com>
> Reported-by: Ravikumar Bangoria <ravi.bangoria at in.ibm.com>
> Signed-off-by: Nicholas Piggin <npiggin at gmail.com>

This one is giving me a proper backtrace when hardlockup happens
with perf_fuzzer so,
Tested-by: Ravi Bangoria <ravi.bangoria at linux.ibm.com>

Neat:
Reported-by: Ravi Bangoria <ravi.bangoria at linux.ibm.com>