From 3474d1b93f897ab33ce160e759afd47d5f412de4 Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Thu, 13 Jun 2024 19:28:27 +0000 Subject: [PATCH] io_uring/io-wq: make io_wq_work flags atomic 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 --- 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 850e30be9322..1052a68fd68d 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 7d3316fe9bfc..913c92249522 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 2b2a6406dd8e..b3b004a7b625 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 57382e523b33..438c44ca3abd 100644 --- a/io_uring/io_uring.c +++ b/io_uring/io_uring.c @@ -462,9 +462,9 @@ 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); @@ -480,7 +480,7 @@ 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); } } @@ -520,7 +520,7 @@ 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); @@ -1736,14 +1736,14 @@ 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; }