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| author |   Pavel Begunkov <asml.silence@gmail.com> | 2021-03-09 00:37:59 +0000 |
|---|---|---|
| committer |   Jens Axboe <axboe@kernel.dk> | 2021-03-10 07:28:42 -0700 |
| commit | 7a612350a989866510dc5c874fd8ffe1f37555d2 (patch) | |
| tree | 4a43e1283d75dfbf6c9fea031c3962007b8071b9 /fs | |
| parent | io_uring: add io_disarm_next() helper (diff) | |
| download | linux-dev-7a612350a989866510dc5c874fd8ffe1f37555d2.tar.xz linux-dev-7a612350a989866510dc5c874fd8ffe1f37555d2.zip | |
io_uring: fix complete_post races for linked req
Calling io_queue_next() after spin_unlock in io_req_complete_post()
races with the other side extracting and reusing this request. Hand
coded parts of io_req_find_next() considering that io_disarm_next()
and io_req_task_queue() have (and safe) to be called with
completion_lock held.
It already does io_commit_cqring() and io_cqring_ev_posted(), so just
reuse it for post io_disarm_next().
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/5672a62f3150ee7c55849f40c0037655c4f2840f.1615250156.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'fs')
| -rw-r--r-- | fs/io_uring.c | 21 |
1 files changed, 14 insertions, 7 deletions
diff --git a/fs/io_uring.c b/fs/io_uring.c index cc9a2cc95608..f7153483a3ac 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -985,6 +985,7 @@ static const struct io_op_def io_op_defs[] = { [IORING_OP_UNLINKAT] = {}, }; +static bool io_disarm_next(struct io_kiocb *req); static void io_uring_del_task_file(unsigned long index); static void io_uring_try_cancel_requests(struct io_ring_ctx *ctx, struct task_struct *task, @@ -1525,15 +1526,14 @@ static void io_cqring_fill_event(struct io_kiocb *req, long res) __io_cqring_fill_event(req, res, 0); } -static inline void io_req_complete_post(struct io_kiocb *req, long res, - unsigned int cflags) +static void io_req_complete_post(struct io_kiocb *req, long res, + unsigned int cflags) { struct io_ring_ctx *ctx = req->ctx; unsigned long flags; spin_lock_irqsave(&ctx->completion_lock, flags); __io_cqring_fill_event(req, res, cflags); - io_commit_cqring(ctx); /* * If we're the last reference to this request, add to our locked * free_list cache. @@ -1541,19 +1541,26 @@ static inline void io_req_complete_post(struct io_kiocb *req, long res, if (refcount_dec_and_test(&req->refs)) { struct io_comp_state *cs = &ctx->submit_state.comp; + if (req->flags & (REQ_F_LINK | REQ_F_HARDLINK)) { + if (req->flags & (REQ_F_LINK_TIMEOUT | REQ_F_FAIL_LINK)) + io_disarm_next(req); + if (req->link) { + io_req_task_queue(req->link); + req->link = NULL; + } + } io_dismantle_req(req); io_put_task(req->task, 1); list_add(&req->compl.list, &cs->locked_free_list); cs->locked_free_nr++; } else req = NULL; + io_commit_cqring(ctx); spin_unlock_irqrestore(&ctx->completion_lock, flags); - io_cqring_ev_posted(ctx); - if (req) { - io_queue_next(req); + + if (req) percpu_ref_put(&ctx->refs); - } } static void io_req_complete_state(struct io_kiocb *req, long res, |