From f7b76ac9d17e16e44feebb6d2749fec92bfd6dd4 Mon Sep 17 00:00:00 2001 From: Zhengyuan Liu Date: Tue, 16 Jul 2019 23:26:14 +0800 Subject: [PATCH] io_uring: fix counter inc/dec mismatch in async_list We could queue a work for each req in defer and link list without increasing async_list->cnt, so we shouldn't decrease it while exiting from workqueue as well if we didn't process the req in async list. Thanks to Jens Axboe for his guidance. Fixes: 31b515106428 ("io_uring: allow workqueue item to handle multiple buffered requests") Signed-off-by: Zhengyuan Liu Signed-off-by: Jens Axboe --- fs/io_uring.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/fs/io_uring.c b/fs/io_uring.c index 708d133492a1..5ec06e5ba0be 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -333,7 +333,8 @@ struct io_kiocb { #define REQ_F_IO_DRAIN 16 /* drain existing IO first */ #define REQ_F_IO_DRAINED 32 /* drain done */ #define REQ_F_LINK 64 /* linked sqes */ -#define REQ_F_FAIL_LINK 128 /* fail rest of links */ +#define REQ_F_LINK_DONE 128 /* linked sqes done */ +#define REQ_F_FAIL_LINK 256 /* fail rest of links */ u64 user_data; u32 result; u32 sequence; @@ -632,6 +633,7 @@ static void io_req_link_next(struct io_kiocb *req) nxt->flags |= REQ_F_LINK; } + nxt->flags |= REQ_F_LINK_DONE; INIT_WORK(&nxt->work, io_sq_wq_submit_work); queue_work(req->ctx->sqo_wq, &nxt->work); } @@ -1844,6 +1846,10 @@ static void io_sq_wq_submit_work(struct work_struct *work) /* async context always use a copy of the sqe */ kfree(sqe); + /* req from defer and link list needn't decrease async cnt */ + if (req->flags & (REQ_F_IO_DRAINED | REQ_F_LINK_DONE)) + goto out; + if (!async_list) break; if (!list_empty(&req_list)) { @@ -1891,6 +1897,7 @@ static void io_sq_wq_submit_work(struct work_struct *work) } } +out: if (cur_mm) { set_fs(old_fs); unuse_mm(cur_mm);