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author | 2018-11-01 00:24:52 +0000 | |
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committer | 2018-12-05 12:16:33 +0100 | |
commit | 2f588cee24caf01c1ac08fff90d67c6af555e7c7 (patch) | |
tree | 6bac641d07aa56fadcd1a7b624ddbec8064fe19b /tools/perf/scripts/python/export-to-postgresql.py | |
parent | tty/ldsem: Add lockdep asserts for ldisc_sem (diff) | |
download | wireguard-linux-2f588cee24caf01c1ac08fff90d67c6af555e7c7.tar.xz wireguard-linux-2f588cee24caf01c1ac08fff90d67c6af555e7c7.zip |
tty/ldsem: Decrement wait_readers on timeouted down_read()
It seems like when ldsem_down_read() fails with timeout, it misses
update for sem->wait_readers. By that reason, when writer finally
releases write end of the semaphore __ldsem_wake_readers() does adjust
sem->count with wrong value:
sem->wait_readers * (LDSEM_ACTIVE_BIAS - LDSEM_WAIT_BIAS)
I.e, if update comes with 1 missed wait_readers decrement, sem->count
will be 0x100000001 which means that there is active reader and it'll
make any further writer to fail in acquiring the semaphore.
It looks like, this is a dead-code, because ldsem_down_read() is never
called with timeout different than MAX_SCHEDULE_TIMEOUT, so it might be
worth to delete timeout parameter and error path fall-back..
Cc: Jiri Slaby <jslaby@suse.com>
Signed-off-by: Dmitry Safonov <dima@arista.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'tools/perf/scripts/python/export-to-postgresql.py')
0 files changed, 0 insertions, 0 deletions