[PATCH AUTOSEL 6.10 082/121] io_uring/io-wq: make io_wq_work flags atomic

Sasha Levin
2024-08-01T00:16:29Z

From: Jens Axboe <axboe@r7625.kernel.dk>

[ Upstream commit 3474d1b93f897ab33ce160e759afd47d5f412de4 ]

The work flags can be set/accessed from different tasks, both the
originator of the request, and the io-wq workers. While modifications
aren't concurrent, it still makes KMSAN unhappy. There's no real
downside to just making the flag reading/manipulation use proper
atomics here.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
include/linux/io_uring_types.h | 2 +-
io_uring/io-wq.c | 19 ++++++++++---------
io_uring/io-wq.h | 2 +-
io_uring/io_uring.c | 12 ++++++------
4 files changed, 18 insertions(+), 17 deletions(-)

diff --git a/include/linux/io_uring_types.h b/include/linux/io_uring_types.h
index 7abdc09271245..abf5c6622af6d 100644
--- a/include/linux/io_uring_types.h
+++ b/include/linux/io_uring_types.h
@@ -50,7 +50,7 @@ struct io_wq_work_list {

struct io_wq_work {
struct io_wq_work_node list;
- unsigned flags;
+ atomic_t flags;
/* place it here instead of io_kiocb as it fills padding and saves 4B */
int cancel_seq;
};
diff --git a/io_uring/io-wq.c b/io_uring/io-wq.c
index 7d3316fe9bfc4..913c92249522e 100644
--- a/io_uring/io-wq.c
+++ b/io_uring/io-wq.c
@@ -159,7 +159,7 @@ static inline struct io_wq_acct *io_get_acct(struct io_wq *wq, bool bound)
static inline struct io_wq_acct *io_work_get_acct(struct io_wq *wq,
struct io_wq_work *work)
{
- return io_get_acct(wq, !(work->flags & IO_WQ_WORK_UNBOUND));
+ return io_get_acct(wq, !(atomic_read(&work->flags) & IO_WQ_WORK_UNBOUND));
}

static inline struct io_wq_acct *io_wq_get_acct(struct io_worker *worker)
@@ -451,7 +451,7 @@ static void __io_worker_idle(struct io_wq *wq, struct io_worker *worker)

static inline unsigned int io_get_work_hash(struct io_wq_work *work)
{
- return work->flags >> IO_WQ_HASH_SHIFT;
+ return atomic_read(&work->flags) >> IO_WQ_HASH_SHIFT;
}

static bool io_wait_on_hash(struct io_wq *wq, unsigned int hash)
@@ -592,8 +592,9 @@ static void io_worker_handle_work(struct io_wq_acct *acct,

next_hashed = wq_next_work(work);

- if (unlikely(do_kill) && (work->flags & IO_WQ_WORK_UNBOUND))
- work->flags |= IO_WQ_WORK_CANCEL;
+ if (do_kill &&
+ (atomic_read(&work->flags) & IO_WQ_WORK_UNBOUND))
+ atomic_or(IO_WQ_WORK_CANCEL, &work->flags);
wq->do_work(work);
io_assign_current_work(worker, NULL);

@@ -891,7 +892,7 @@ static bool io_wq_worker_wake(struct io_worker *worker, void *data)
static void io_run_cancel(struct io_wq_work *work, struct io_wq *wq)
{
do {
- work->flags |= IO_WQ_WORK_CANCEL;
+ atomic_or(IO_WQ_WORK_CANCEL, &work->flags);
wq->do_work(work);
work = wq->free_work(work);
} while (work);
@@ -926,7 +927,7 @@ static bool io_wq_work_match_item(struct io_wq_work *work, void *data)
void io_wq_enqueue(struct io_wq *wq, struct io_wq_work *work)
{
struct io_wq_acct *acct = io_work_get_acct(wq, work);
- unsigned long work_flags = work->flags;
+ unsigned int work_flags = atomic_read(&work->flags);
struct io_cb_cancel_data match = {
.fn = io_wq_work_match_item,
.data = work,
@@ -939,7 +940,7 @@ void io_wq_enqueue(struct io_wq *wq, struct io_wq_work *work)
* been marked as one that should not get executed, cancel it here.
*/
if (test_bit(IO_WQ_BIT_EXIT, &wq->state) ||
- (work->flags & IO_WQ_WORK_CANCEL)) {
+ (work_flags & IO_WQ_WORK_CANCEL)) {
io_run_cancel(work, wq);
return;
}
@@ -982,7 +983,7 @@ void io_wq_hash_work(struct io_wq_work *work, void *val)
unsigned int bit;

bit = hash_ptr(val, IO_WQ_HASH_ORDER);
- work->flags |= (IO_WQ_WORK_HASHED | (bit << IO_WQ_HASH_SHIFT));
+ atomic_or(IO_WQ_WORK_HASHED | (bit << IO_WQ_HASH_SHIFT), &work->flags);
}

static bool __io_wq_worker_cancel(struct io_worker *worker,
@@ -990,7 +991,7 @@ static bool __io_wq_worker_cancel(struct io_worker *worker,
struct io_wq_work *work)
{
if (work && match->fn(work, match->data)) {
- work->flags |= IO_WQ_WORK_CANCEL;
+ atomic_or(IO_WQ_WORK_CANCEL, &work->flags);
__set_notify_signal(worker->task);
return true;
}
diff --git a/io_uring/io-wq.h b/io_uring/io-wq.h
index 2b2a6406dd8ee..b3b004a7b6252 100644
--- a/io_uring/io-wq.h
+++ b/io_uring/io-wq.h
@@ -56,7 +56,7 @@ bool io_wq_worker_stopped(void);

static inline bool io_wq_is_hashed(struct io_wq_work *work)
{
- return work->flags & IO_WQ_WORK_HASHED;
+ return atomic_read(&work->flags) & IO_WQ_WORK_HASHED;
}

typedef bool (work_cancel_fn)(struct io_wq_work *, void *);
diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
index c326e2127dd4d..846c1cecdb0aa 100644
--- a/io_uring/io_uring.c
+++ b/io_uring/io_uring.c
@@ -461,9 +461,9 @@ static void io_prep_async_work(struct io_kiocb *req)
}

req->work.list.next = NULL;
- req->work.flags = 0;
+ atomic_set(&req->work.flags, 0);
if (req->flags & REQ_F_FORCE_ASYNC)
- req->work.flags |= IO_WQ_WORK_CONCURRENT;
+ atomic_or(IO_WQ_WORK_CONCURRENT, &req->work.flags);

if (req->file && !(req->flags & REQ_F_FIXED_FILE))
req->flags |= io_file_get_flags(req->file);
@@ -479,7 +479,7 @@ static void io_prep_async_work(struct io_kiocb *req)
io_wq_hash_work(&req->work, file_inode(req->file));
} else if (!req->file || !S_ISBLK(file_inode(req->file)->i_mode)) {
if (def->unbound_nonreg_file)
- req->work.flags |= IO_WQ_WORK_UNBOUND;
+ atomic_or(IO_WQ_WORK_UNBOUND, &req->work.flags);
}
}

@@ -519,7 +519,7 @@ static void io_queue_iowq(struct io_kiocb *req)
* worker for it).
*/
if (WARN_ON_ONCE(!same_thread_group(req->task, current)))
- req->work.flags |= IO_WQ_WORK_CANCEL;
+ atomic_or(IO_WQ_WORK_CANCEL, &req->work.flags);

trace_io_uring_queue_async_work(req, io_wq_is_hashed(&req->work));
io_wq_enqueue(tctx->io_wq, &req->work);
@@ -1813,14 +1813,14 @@ void io_wq_submit_work(struct io_wq_work *work)
io_arm_ltimeout(req);

/* either cancelled or io-wq is dying, so don't touch tctx->iowq */
- if (work->flags & IO_WQ_WORK_CANCEL) {
+ if (atomic_read(&work->flags) & IO_WQ_WORK_CANCEL) {
fail:
io_req_task_queue_fail(req, err);
return;
}
if (!io_assign_file(req, def, issue_flags)) {
err = -EBADF;
- work->flags |= IO_WQ_WORK_CANCEL;
+ atomic_or(IO_WQ_WORK_CANCEL, &work->flags);
goto fail;
}

--
2.43.0