diff options
author | Christoph Hellwig <hch@lst.de> | 2018-05-20 20:19:30 +0300 |
---|---|---|
committer | Christoph Hellwig <hch@lst.de> | 2018-05-26 10:16:44 +0300 |
commit | 1962da0d2198a00a056a2915fbc6ec684c3bef0a (patch) | |
tree | aec374beb42fb7e8d6dc95a602a1cd257df3ba82 | |
parent | 2c14fa838cbefc23cf1c73ca167ed85b274b2913 (diff) | |
download | linux-1962da0d2198a00a056a2915fbc6ec684c3bef0a.tar.xz |
aio: try to complete poll iocbs without context switch
If we can acquire ctx_lock without spinning we can just remove our
iocb from the active_reqs list, and thus complete the iocbs from the
wakeup context.
Signed-off-by: Christoph Hellwig <hch@lst.de>
-rw-r--r-- | fs/aio.c | 20 |
1 files changed, 17 insertions, 3 deletions
@@ -1633,6 +1633,7 @@ static int aio_poll_wake(struct wait_queue_entry *wait, unsigned mode, int sync, void *key) { struct poll_iocb *req = container_of(wait, struct poll_iocb, wait); + struct aio_kiocb *iocb = container_of(req, struct aio_kiocb, poll); struct file *file = req->file; __poll_t mask = key_to_poll(key); @@ -1648,9 +1649,22 @@ static int aio_poll_wake(struct wait_queue_entry *wait, unsigned mode, int sync, __aio_poll_remove(req); - req->events = mask; - INIT_WORK(&req->work, aio_poll_work); - schedule_work(&req->work); + /* + * Try completing without a context switch if we can acquire ctx_lock + * without spinning. Otherwise we need to defer to a workqueue to + * avoid a deadlock due to the lock order. + */ + if (spin_trylock(&iocb->ki_ctx->ctx_lock)) { + list_del_init(&iocb->ki_list); + spin_unlock(&iocb->ki_ctx->ctx_lock); + + __aio_poll_complete(req, mask); + } else { + req->events = mask; + INIT_WORK(&req->work, aio_poll_work); + schedule_work(&req->work); + } + return 1; } |