diff options
| author | Pavel Begunkov <asml.silence@gmail.com> | 2020-11-25 18:41:28 +0000 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2020-11-26 08:50:21 -0700 |
| commit | af60470347de6ac2b9f0cc3703975a543a3de075 (patch) | |
| tree | 6b0d7677d948ebb14a02c02fca16c9f63d6644cb /fs | |
| parent | 9c3a205c5ffa36e96903c2e37eb5f41c0f03c43e (diff) | |
io_uring: fix files grab/cancel race
When one task is in io_uring_cancel_files() and another is doing
io_prep_async_work() a race may happen. That's because after accounting
a request inflight in first call to io_grab_identity() it still may fail
and go to io_identity_cow(), which migh briefly keep dangling
work.identity and not only.
Grab files last, so io_prep_async_work() won't fail if it did get into
->inflight_list.
note: the bug shouldn't exist after making io_uring_cancel_files() not
poking into other tasks' requests.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'fs')
| -rw-r--r-- | fs/io_uring.c | 31 |
1 files changed, 15 insertions, 16 deletions
diff --git a/fs/io_uring.c b/fs/io_uring.c index ff6deffe5aa9..1023f7b44cea 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -1313,22 +1313,6 @@ static bool io_grab_identity(struct io_kiocb *req) return false; req->work.flags |= IO_WQ_WORK_FSIZE; } - - if (!(req->work.flags & IO_WQ_WORK_FILES) && - (def->work_flags & IO_WQ_WORK_FILES) && - !(req->flags & REQ_F_NO_FILE_TABLE)) { - if (id->files != current->files || - id->nsproxy != current->nsproxy) - return false; - atomic_inc(&id->files->count); - get_nsproxy(id->nsproxy); - req->flags |= REQ_F_INFLIGHT; - - spin_lock_irq(&ctx->inflight_lock); - list_add(&req->inflight_entry, &ctx->inflight_list); - spin_unlock_irq(&ctx->inflight_lock); - req->work.flags |= IO_WQ_WORK_FILES; - } #ifdef CONFIG_BLK_CGROUP if (!(req->work.flags & IO_WQ_WORK_BLKCG) && (def->work_flags & IO_WQ_WORK_BLKCG)) { @@ -1370,6 +1354,21 @@ static bool io_grab_identity(struct io_kiocb *req) } spin_unlock(¤t->fs->lock); } + if (!(req->work.flags & IO_WQ_WORK_FILES) && + (def->work_flags & IO_WQ_WORK_FILES) && + !(req->flags & REQ_F_NO_FILE_TABLE)) { + if (id->files != current->files || + id->nsproxy != current->nsproxy) + return false; + atomic_inc(&id->files->count); + get_nsproxy(id->nsproxy); + req->flags |= REQ_F_INFLIGHT; + + spin_lock_irq(&ctx->inflight_lock); + list_add(&req->inflight_entry, &ctx->inflight_list); + spin_unlock_irq(&ctx->inflight_lock); + req->work.flags |= IO_WQ_WORK_FILES; + } return true; } |