s390/smp: avoid concurrent write to sigp status field

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When a sigp instruction is issued it may store a status. This status is
currently stored in a per cpu field of the target cpu.
If multiple cpus issue a sigp instruction with the same target cpu
and a status is stored the result is not necessarily as expected.

Currently this is not an issue:
- on cpu hotplug no sigps, except "restart" and "sense" are sent to the
  target cpu.
- on external call we don't look at the status if it is stored
- on sense running the condition code "status stored" is sufficient to
  tell if a cpu is running or not

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

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This commit is contained in:

Heiko Carstens 2012-08-30 14:24:42 +02:00 • committed by Martin Schwidefsky

parent fbf3c54239

commit c5e3acd666

1 changed files with 7 additions and 6 deletions

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arch/s390/kernel/smp.c

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