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.
[email@example.com: simplifications, per Daniel]
Signed-off-by: Douglas Anderson <firstname.lastname@example.org>
Reviewed-by: Daniel Thompson <email@example.com>
Cc: Jason Wessel <firstname.lastname@example.org>
Cc: Brian Norris <email@example.com>
Signed-off-by: Andrew Morton <firstname.lastname@example.org>
Signed-off-by: Linus Torvalds <email@example.com>
Signed-off-by: Greg Kroah-Hartman <firstname.lastname@example.org>
1 file changed