Revert f5d6a52f5111 ("x86/smpboot: Skip delays during SMP initialization similar...
authorIngo Molnar <mingo@kernel.org>
Wed, 13 May 2015 06:40:49 +0000 (08:40 +0200)
committerIngo Molnar <mingo@kernel.org>
Wed, 13 May 2015 06:40:49 +0000 (08:40 +0200)
commit853b160aaafbe27d6304c8832bb7340d57c6b04e
treedfe6c28201a92ec75c895a4114b40762a750f11f
parent1a744cb356c57303fc97eb15a298032170f841fa
Revert f5d6a52f5111 ("x86/smpboot: Skip delays during SMP initialization similar to Xen")

Huang Ying reported x86 boot hangs due to this commit.

Turns out that the change, despite its changelog, does more
than just change timeouts: it also changes the way we
assert/deassert INIT via the APIC_DM_INIT IPI, in the x2apic
case it skips the deassert step.

This is historically fragile code and the patch did not
improve it, so revert these changes.

This commit:

  1a744cb356c5 ("x86/smp/boot: Remove 10ms delay from cpu_up() on modern processors")

independently removes the worst of the delays (the 10 msec delay).

The remaining delays can be addressed one by one, combined
with careful testing.

Reported-by: Huang Ying <ying.huang@intel.com>
Cc: Anthony Liguori <aliguori@amazon.com>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Gang Wei <gang.wei@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Jan H. Schönherr <jschoenh@amazon.de>
Cc: Len Brown <len.brown@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tim Deegan <tim@xen.org>
Link: http://lkml.kernel.org/r/1430732554-7294-1-git-send-email-jschoenh@amazon.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
arch/x86/kernel/smpboot.c