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Date: Tue, 12 Apr 2022 08:32:41 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-kernel@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
stable@...r.kernel.org,
syzbot+c4b9303500a21750b250@...kaller.appspotmail.com,
Jens Axboe <axboe@...nel.dk>
Subject: [PATCH 5.17 343/343] io_uring: drop the old style inflight file tracking
From: Jens Axboe <axboe@...nel.dk>
commit d5361233e9ab920e135819f73dd8466355f1fddd upstream.
io_uring tracks requests that are referencing an io_uring descriptor to
be able to cancel without worrying about loops in the references. Since
we now assign the file at execution time, the easier approach is to drop
a potentially problematic reference before we punt the request. This
eliminates the need to special case these types of files beyond just
marking them as such, and simplifies cancelation quite a bit.
This also fixes a recent issue where an async punted tee operation would
with the io_uring descriptor as the output file would crash when
attempting to get a reference to the file from the io-wq worker. We
could have worked around that, but this is the much cleaner fix.
Fixes: 6bf9c47a3989 ("io_uring: defer file assignment")
Reported-by: syzbot+c4b9303500a21750b250@...kaller.appspotmail.com
Signed-off-by: Jens Axboe <axboe@...nel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
fs/io_uring.c | 85 ++++++++++++++++++----------------------------------------
1 file changed, 27 insertions(+), 58 deletions(-)
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -112,8 +112,7 @@
IOSQE_IO_DRAIN | IOSQE_CQE_SKIP_SUCCESS)
#define IO_REQ_CLEAN_FLAGS (REQ_F_BUFFER_SELECTED | REQ_F_NEED_CLEANUP | \
- REQ_F_POLLED | REQ_F_INFLIGHT | REQ_F_CREDS | \
- REQ_F_ASYNC_DATA)
+ REQ_F_POLLED | REQ_F_CREDS | REQ_F_ASYNC_DATA)
#define IO_TCTX_REFS_CACHE_NR (1U << 10)
@@ -469,7 +468,6 @@ struct io_uring_task {
const struct io_ring_ctx *last;
struct io_wq *io_wq;
struct percpu_counter inflight;
- atomic_t inflight_tracked;
atomic_t in_idle;
spinlock_t task_lock;
@@ -1131,6 +1129,8 @@ static void io_clean_op(struct io_kiocb
static inline struct file *io_file_get_fixed(struct io_kiocb *req, int fd,
unsigned issue_flags);
static inline struct file *io_file_get_normal(struct io_kiocb *req, int fd);
+static void io_drop_inflight_file(struct io_kiocb *req);
+static bool io_assign_file(struct io_kiocb *req, unsigned int issue_flags);
static void __io_queue_sqe(struct io_kiocb *req);
static void io_rsrc_put_work(struct work_struct *work);
@@ -1312,29 +1312,9 @@ static bool io_match_task(struct io_kioc
bool cancel_all)
__must_hold(&req->ctx->timeout_lock)
{
- struct io_kiocb *req;
-
if (task && head->task != task)
return false;
- if (cancel_all)
- return true;
-
- io_for_each_link(req, head) {
- if (req->flags & REQ_F_INFLIGHT)
- return true;
- }
- return false;
-}
-
-static bool io_match_linked(struct io_kiocb *head)
-{
- struct io_kiocb *req;
-
- io_for_each_link(req, head) {
- if (req->flags & REQ_F_INFLIGHT)
- return true;
- }
- return false;
+ return cancel_all;
}
/*
@@ -1344,24 +1324,9 @@ static bool io_match_linked(struct io_ki
static bool io_match_task_safe(struct io_kiocb *head, struct task_struct *task,
bool cancel_all)
{
- bool matched;
-
if (task && head->task != task)
return false;
- if (cancel_all)
- return true;
-
- if (head->flags & REQ_F_LINK_TIMEOUT) {
- struct io_ring_ctx *ctx = head->ctx;
-
- /* protect against races with linked timeouts */
- spin_lock_irq(&ctx->timeout_lock);
- matched = io_match_linked(head);
- spin_unlock_irq(&ctx->timeout_lock);
- } else {
- matched = io_match_linked(head);
- }
- return matched;
+ return cancel_all;
}
static inline bool req_has_async_data(struct io_kiocb *req)
@@ -1509,14 +1474,6 @@ static inline bool io_req_ffs_set(struct
return req->flags & REQ_F_FIXED_FILE;
}
-static inline void io_req_track_inflight(struct io_kiocb *req)
-{
- if (!(req->flags & REQ_F_INFLIGHT)) {
- req->flags |= REQ_F_INFLIGHT;
- atomic_inc(¤t->io_uring->inflight_tracked);
- }
-}
-
static struct io_kiocb *__io_prep_linked_timeout(struct io_kiocb *req)
{
if (WARN_ON_ONCE(!req->link))
@@ -2380,6 +2337,8 @@ static void io_req_task_work_add(struct
WARN_ON_ONCE(!tctx);
+ io_drop_inflight_file(req);
+
spin_lock_irqsave(&tctx->task_lock, flags);
if (priority)
wq_list_add_tail(&req->io_task_work.node, &tctx->prior_task_list);
@@ -5548,7 +5507,10 @@ static int io_poll_check_events(struct i
if (!req->result) {
struct poll_table_struct pt = { ._key = poll->events };
- req->result = vfs_poll(req->file, &pt) & poll->events;
+ if (unlikely(!io_assign_file(req, IO_URING_F_UNLOCKED)))
+ req->result = -EBADF;
+ else
+ req->result = vfs_poll(req->file, &pt) & poll->events;
}
/* multishot, just fill an CQE and proceed */
@@ -6731,11 +6693,6 @@ static void io_clean_op(struct io_kiocb
kfree(req->apoll);
req->apoll = NULL;
}
- if (req->flags & REQ_F_INFLIGHT) {
- struct io_uring_task *tctx = req->task->io_uring;
-
- atomic_dec(&tctx->inflight_tracked);
- }
if (req->flags & REQ_F_CREDS)
put_cred(req->creds);
if (req->flags & REQ_F_ASYNC_DATA) {
@@ -7024,6 +6981,19 @@ out:
return file;
}
+/*
+ * Drop the file for requeue operations. Only used of req->file is the
+ * io_uring descriptor itself.
+ */
+static void io_drop_inflight_file(struct io_kiocb *req)
+{
+ if (unlikely(req->flags & REQ_F_INFLIGHT)) {
+ fput(req->file);
+ req->file = NULL;
+ req->flags &= ~REQ_F_INFLIGHT;
+ }
+}
+
static struct file *io_file_get_normal(struct io_kiocb *req, int fd)
{
struct file *file = fget(fd);
@@ -7031,8 +7001,8 @@ static struct file *io_file_get_normal(s
trace_io_uring_file_get(req->ctx, fd);
/* we don't allow fixed io_uring files */
- if (file && unlikely(file->f_op == &io_uring_fops))
- io_req_track_inflight(req);
+ if (file && file->f_op == &io_uring_fops)
+ req->flags |= REQ_F_INFLIGHT;
return file;
}
@@ -8804,7 +8774,6 @@ static __cold int io_uring_alloc_task_co
xa_init(&tctx->xa);
init_waitqueue_head(&tctx->wait);
atomic_set(&tctx->in_idle, 0);
- atomic_set(&tctx->inflight_tracked, 0);
task->io_uring = tctx;
spin_lock_init(&tctx->task_lock);
INIT_WQ_LIST(&tctx->task_list);
@@ -9942,7 +9911,7 @@ static __cold void io_uring_clean_tctx(s
static s64 tctx_inflight(struct io_uring_task *tctx, bool tracked)
{
if (tracked)
- return atomic_read(&tctx->inflight_tracked);
+ return 0;
return percpu_counter_sum(&tctx->inflight);
}
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