[PATCH] deal with rmmod/put_io_context() races
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/block/as-iosched.c b/block/as-iosched.c
index d2ee2af..55a997f 100644
--- a/block/as-iosched.c
+++ b/block/as-iosched.c
@@ -182,6 +182,9 @@
static kmem_cache_t *arq_pool;
+static atomic_t ioc_count = ATOMIC_INIT(0);
+static struct completion *ioc_gone;
+
static void as_move_to_dispatch(struct as_data *ad, struct as_rq *arq);
static void as_antic_stop(struct as_data *ad);
@@ -193,11 +196,14 @@
static void free_as_io_context(struct as_io_context *aic)
{
kfree(aic);
+ if (atomic_dec_and_test(&ioc_count) && ioc_gone)
+ complete(ioc_gone);
}
static void as_trim(struct io_context *ioc)
{
- kfree(ioc->aic);
+ if (ioc->aic)
+ free_as_io_context(ioc->aic);
ioc->aic = NULL;
}
@@ -226,6 +232,7 @@
ret->seek_total = 0;
ret->seek_samples = 0;
ret->seek_mean = 0;
+ atomic_inc(&ioc_count);
}
return ret;
@@ -1900,7 +1907,13 @@
static void __exit as_exit(void)
{
+ DECLARE_COMPLETION(all_gone);
elv_unregister(&iosched_as);
+ ioc_gone = &all_gone;
+ barrier();
+ if (atomic_read(&ioc_count))
+ complete(ioc_gone);
+ synchronize_rcu();
kmem_cache_destroy(arq_pool);
}