diff options
| author | Douglas Anderson <dianders@chromium.org> | 2016-12-14 15:05:49 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2016-12-14 16:04:08 -0800 |
| commit | 2d13bb6494c807bcf3f78af0e96c0b8615a94385 (patch) | |
| tree | f81c9862fc1119f34eb9584aedeed49471613ea4 | |
| parent | db862358a4a96f52d3b0c713c703828f90d97de9 (diff) | |
kernel/debug/debug_core.c: more properly delay for secondary CPUs
We've got a delay loop waiting for secondary CPUs. That loop uses
loops_per_jiffy. However, loops_per_jiffy doesn't actually mean how
many tight loops make up a jiffy on all architectures. It is quite
common to see things like this in the boot log:
Calibrating delay loop (skipped), value calculated using timer
frequency.. 48.00 BogoMIPS (lpj=24000)
In my case I was seeing lots of cases where other CPUs timed out
entering the debugger only to print their stack crawls shortly after the
kdb> prompt was written.
Elsewhere in kgdb we already use udelay(), so that should be safe enough
to use to implement our timeout. We'll delay 1 ms for 1000 times, which
should give us a full second of delay (just like the old code wanted)
but allow us to notice that we're done every 1 ms.
[akpm@linux-foundation.org: simplifications, per Daniel]
Link: http://lkml.kernel.org/r/1477091361-2039-1-git-send-email-dianders@chromium.org
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
Cc: Jason Wessel <jason.wessel@windriver.com>
Cc: Brian Norris <briannorris@chromium.org>
Cc: <stable@vger.kernel.org> [4.0+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| -rw-r--r-- | kernel/debug/debug_core.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/kernel/debug/debug_core.c b/kernel/debug/debug_core.c index 0874e2edd275..79517e5549f1 100644 --- a/kernel/debug/debug_core.c +++ b/kernel/debug/debug_core.c @@ -598,11 +598,11 @@ return_normal: /* * Wait for the other CPUs to be notified and be waiting for us: */ - time_left = loops_per_jiffy * HZ; + time_left = MSEC_PER_SEC; while (kgdb_do_roundup && --time_left && (atomic_read(&masters_in_kgdb) + atomic_read(&slaves_in_kgdb)) != online_cpus) - cpu_relax(); + udelay(1000); if (!time_left) pr_crit("Timed out waiting for secondary CPUs.\n"); |