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| author | Jens Axboe <jaxboe@fusionio.com> | 2011-04-19 11:10:35 +0400 |
|---|---|---|
| committer | Jens Axboe <jaxboe@fusionio.com> | 2011-04-19 11:10:35 +0400 |
| commit | 5f45c69589b7d2953584e6cd0b31e35dbe960ad0 (patch) | |
| tree | 7f920cebcbbe6a1435975e355cee15289ddbc428 /block/cfq-iosched.c | |
| parent | bd900d4580107c899d43b262fbbd995f11097a43 (diff) | |
| download | linux-5f45c69589b7d2953584e6cd0b31e35dbe960ad0.tar.xz | |
cfq-iosched: read_lock() does not always imply rcu_read_lock()
For some configurations of CONFIG_PREEMPT that is not true. So
get rid of __call_for_each_cic() and always uses the explicitly
rcu_read_lock() protected call_for_each_cic() instead.
This fixes a potential bug related to IO scheduler removal or
online switching.
Thanks to Paul McKenney for clarifying this.
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
Diffstat (limited to 'block/cfq-iosched.c')
| -rw-r--r-- | block/cfq-iosched.c | 20 |
1 files changed, 6 insertions, 14 deletions
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c index 46b0a1d1d925..5b52011e3a40 100644 --- a/block/cfq-iosched.c +++ b/block/cfq-iosched.c @@ -2582,28 +2582,20 @@ static void cfq_put_queue(struct cfq_queue *cfqq) } /* - * Must always be called with the rcu_read_lock() held + * Call func for each cic attached to this ioc. */ static void -__call_for_each_cic(struct io_context *ioc, - void (*func)(struct io_context *, struct cfq_io_context *)) +call_for_each_cic(struct io_context *ioc, + void (*func)(struct io_context *, struct cfq_io_context *)) { struct cfq_io_context *cic; struct hlist_node *n; + rcu_read_lock(); + hlist_for_each_entry_rcu(cic, n, &ioc->cic_list, cic_list) func(ioc, cic); -} -/* - * Call func for each cic attached to this ioc. - */ -static void -call_for_each_cic(struct io_context *ioc, - void (*func)(struct io_context *, struct cfq_io_context *)) -{ - rcu_read_lock(); - __call_for_each_cic(ioc, func); rcu_read_unlock(); } @@ -2664,7 +2656,7 @@ static void cfq_free_io_context(struct io_context *ioc) * should be ok to iterate over the known list, we will see all cic's * since no new ones are added. */ - __call_for_each_cic(ioc, cic_free_func); + call_for_each_cic(ioc, cic_free_func); } static void cfq_put_cooperator(struct cfq_queue *cfqq) |