android_kernel_oneplus_msm8998/kernel/debug
Douglas Anderson f93777c915 kernel/debug/debug_core.c: more properly delay for secondary CPUs
commit 2d13bb6494c807bcf3f78af0e96c0b8615a94385 upstream.

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>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-01-06 11:16:16 +01:00
..
kdb kdb: Const qualifier for kdb_getstr's prompt argument 2015-02-19 12:39:03 -06:00
debug_core.c kernel/debug/debug_core.c: more properly delay for secondary CPUs 2017-01-06 11:16:16 +01:00
debug_core.h kgdb/kdb: Fix no KDB config problem 2014-01-25 08:55:09 +01:00
gdbstub.c KGDB/KDB fixes and cleanups 2013-03-02 08:31:39 -08:00
Makefile kdb: core for kgdb back end (1 of 2) 2010-05-20 21:04:20 -05:00