git: fq - fix a (possible) deadlock
commit 009da86a5800b6fefcda0a946ab02a089bd9254f
Author: Alex Hornung <ahornung@gmail.com>
Date: Fri Aug 26 00:29:17 2011 +0000
fq - fix a (possible) deadlock
* A deadlock can occur if a lock is held around the strategy call when
the completion is synchronous and ends up in the destruction of a
tdio, as both will acquire the same diskctx lock.
* Refactor the code around strategy calls so that the bios are first
prepared, under the protection of the lock, and inserted into a local
array. Once that is ready and the bios are ready and taken out of
their respective queues, the locks are dropped and the strategy call
occurs locklessly.
Reported-by: Antonio Huete (tuxillo@)
Summary of changes:
sys/kern/dsched/fq/fq.h | 7 +++++++
sys/kern/dsched/fq/fq_core.c | 39 +++++++++++++++++++++++++++++++++++----
sys/kern/dsched/fq/fq_diskops.c | 25 +++++++++++++++++++++++--
3 files changed, 65 insertions(+), 6 deletions(-)
http://gitweb.dragonflybsd.org/dragonfly.git/commitdiff/009da86a5800b6fefcda0a946ab02a089bd9254f
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