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authorLinus Torvalds <torvalds@linux-foundation.org>2020-03-13 13:00:08 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2020-03-13 13:00:08 -0700
commit5007928eaeb7681501e94ac7516f6c6200f993fa (patch)
treee53f3fcded4d1f2b148074edf7c1e96d5a73491f /fs
parent17829c5a42f776463b305f8a9ccac55a3f473e1d (diff)
parent805b13adde3964c78cba125a15527e88c19f87b3 (diff)
Merge tag 'io_uring-5.6-2020-03-13' of git://git.kernel.dk/linux-block
Pull io_uring fix from Jens Axboe: "Just a single fix here, improving the RCU callback ordering from last week. After a bit more perusing by Paul, he poked a hole in the original" * tag 'io_uring-5.6-2020-03-13' of git://git.kernel.dk/linux-block: io_uring: ensure RCU callback ordering with rcu_barrier()
Diffstat (limited to 'fs')
-rw-r--r--fs/io_uring.c29
1 files changed, 13 insertions, 16 deletions
diff --git a/fs/io_uring.c b/fs/io_uring.c
index c06082bb039a..1b2517291b78 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -191,7 +191,6 @@ struct fixed_file_data {
struct llist_head put_llist;
struct work_struct ref_work;
struct completion done;
- struct rcu_head rcu;
};
struct io_ring_ctx {
@@ -5331,24 +5330,21 @@ static void io_file_ref_kill(struct percpu_ref *ref)
complete(&data->done);
}
-static void __io_file_ref_exit_and_free(struct rcu_head *rcu)
+static void io_file_ref_exit_and_free(struct work_struct *work)
{
- struct fixed_file_data *data = container_of(rcu, struct fixed_file_data,
- rcu);
- percpu_ref_exit(&data->refs);
- kfree(data);
-}
+ struct fixed_file_data *data;
+
+ data = container_of(work, struct fixed_file_data, ref_work);
-static void io_file_ref_exit_and_free(struct rcu_head *rcu)
-{
/*
- * We need to order our exit+free call against the potentially
- * existing call_rcu() for switching to atomic. One way to do that
- * is to have this rcu callback queue the final put and free, as we
- * could otherwise have a pre-existing atomic switch complete _after_
- * the free callback we queued.
+ * Ensure any percpu-ref atomic switch callback has run, it could have
+ * been in progress when the files were being unregistered. Once
+ * that's done, we can safely exit and free the ref and containing
+ * data structure.
*/
- call_rcu(rcu, __io_file_ref_exit_and_free);
+ rcu_barrier();
+ percpu_ref_exit(&data->refs);
+ kfree(data);
}
static int io_sqe_files_unregister(struct io_ring_ctx *ctx)
@@ -5369,7 +5365,8 @@ static int io_sqe_files_unregister(struct io_ring_ctx *ctx)
for (i = 0; i < nr_tables; i++)
kfree(data->table[i].files);
kfree(data->table);
- call_rcu(&data->rcu, io_file_ref_exit_and_free);
+ INIT_WORK(&data->ref_work, io_file_ref_exit_and_free);
+ queue_work(system_wq, &data->ref_work);
ctx->file_data = NULL;
ctx->nr_user_files = 0;
return 0;