s390/cmm: avoid add_timer on concurrently used timer

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cmm_set_timer could be called concurrently from cmm_thread, cmm proc
handler, upon cmm smsg receive and timer function itself. To avoid
potential race condition and hitting BUG_ON in add_timer on already
pending timer simply reuse mod_timer which is according to
documentation "the only safe way to modify the timeout" with multiple
unserialized concurrent users. mod_timer can handle both active and
inactive timers which allows to carry out minor code simplification as
well.

Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

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Vasily Gorbik 2018-07-13 08:13:13 +02:00 • committed by Martin Schwidefsky

parent a09baa9543

commit ac4c4fc87d

1 changed files with 1 additions and 6 deletions

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arch/s390/mm/cmm.c

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