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v0.5.1
https://github.com/torvalds/linux
02 December 2023, 22:23:51 UTC
Revision 3d483f47579461a4715db33c68ef8752e5a97a2d authored by Eric W. Biederman on 29 July 2005, 21:03:29 UTC, committed by Linus Torvalds on 29 July 2005, 22:01:13 UTC 
[PATCH] Fix sync_tsc hang
 
sync_tsc was using smp_call_function to ask the boot processor to report
it's tsc value.  smp_call_function performs an IPI_send_allbutself which is
a broadcast ipi.  There is a window during processor startup during which
the target cpu has started and before it has initialized it's interrupt
vectors so it can properly process an interrupt.  Receveing an interrupt
during that window will triple fault the cpu and do other nasty things.

Why cli does not protect us from that is beyond me.

The simple fix is to match ia64 and provide a smp_call_function_single.
Which avoids the broadcast and is more efficient.

This certainly fixes the problem of getting stuck on boot which was
very easy to trigger on my SMP Hyperthreaded Xeon, and I think
it fixes it for the right reasons.

Minor changes by AK

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
1 parent 94d2ac6
History
Tip revision: 3d483f47579461a4715db33c68ef8752e5a97a2d authored by Eric W. Biederman on 29 July 2005, 21:03:29 UTC
[PATCH] Fix sync_tsc hang
Tip revision: 3d483f4
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