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| author | Stefan Bühler <source@stbuehler.de> | 2019-05-11 19:08:01 +0200 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2019-05-13 09:15:42 -0600 |
| commit | e2033e33cb3821c26d4f9e70677910827d3b7885 (patch) | |
| tree | 9a4c0da34b35916590b1104581ccd89339ea6d94 /fs/io_uring.c | |
| parent | a13f0655503a4a89df67fdc7cac6a7810795d4b3 (diff) | |
| download | lwn-e2033e33cb3821c26d4f9e70677910827d3b7885.tar.gz lwn-e2033e33cb3821c26d4f9e70677910827d3b7885.zip | |
io_uring: fix race condition reading SQE data
When punting to workers the SQE gets copied after the initial try.
There is a race condition between reading SQE data for the initial try
and copying it for punting it to the workers.
For example io_rw_done calls kiocb->ki_complete even if it was prepared
for IORING_OP_FSYNC (and would be NULL).
The easiest solution for now is to alway prepare again in the worker.
req->file is safe to prepare though as long as it is checked before use.
Signed-off-by: Stefan Bühler <source@stbuehler.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'fs/io_uring.c')
| -rw-r--r-- | fs/io_uring.c | 17 |
1 files changed, 2 insertions, 15 deletions
diff --git a/fs/io_uring.c b/fs/io_uring.c index 48ea3977012a..576d9c652b4c 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -329,9 +329,8 @@ struct io_kiocb { #define REQ_F_IOPOLL_COMPLETED 2 /* polled IO has completed */ #define REQ_F_FIXED_FILE 4 /* ctx owns file */ #define REQ_F_SEQ_PREV 8 /* sequential with previous */ -#define REQ_F_PREPPED 16 /* prep already done */ -#define REQ_F_IO_DRAIN 32 /* drain existing IO first */ -#define REQ_F_IO_DRAINED 64 /* drain done */ +#define REQ_F_IO_DRAIN 16 /* drain existing IO first */ +#define REQ_F_IO_DRAINED 32 /* drain done */ u64 user_data; u32 error; /* iopoll result from callback */ u32 sequence; @@ -896,9 +895,6 @@ static int io_prep_rw(struct io_kiocb *req, const struct sqe_submit *s, if (!req->file) return -EBADF; - /* For -EAGAIN retry, everything is already prepped */ - if (req->flags & REQ_F_PREPPED) - return 0; if (force_nonblock && !io_file_supports_async(req->file)) force_nonblock = false; @@ -941,7 +937,6 @@ static int io_prep_rw(struct io_kiocb *req, const struct sqe_submit *s, return -EINVAL; kiocb->ki_complete = io_complete_rw; } - req->flags |= REQ_F_PREPPED; return 0; } @@ -1227,16 +1222,12 @@ static int io_prep_fsync(struct io_kiocb *req, const struct io_uring_sqe *sqe) if (!req->file) return -EBADF; - /* Prep already done (EAGAIN retry) */ - if (req->flags & REQ_F_PREPPED) - return 0; if (unlikely(ctx->flags & IORING_SETUP_IOPOLL)) return -EINVAL; if (unlikely(sqe->addr || sqe->ioprio || sqe->buf_index)) return -EINVAL; - req->flags |= REQ_F_PREPPED; return 0; } @@ -1277,16 +1268,12 @@ static int io_prep_sfr(struct io_kiocb *req, const struct io_uring_sqe *sqe) if (!req->file) return -EBADF; - /* Prep already done (EAGAIN retry) */ - if (req->flags & REQ_F_PREPPED) - return 0; if (unlikely(ctx->flags & IORING_SETUP_IOPOLL)) return -EINVAL; if (unlikely(sqe->addr || sqe->ioprio || sqe->buf_index)) return -EINVAL; - req->flags |= REQ_F_PREPPED; return ret; } |