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io_uring/io-wq: forward submission ref to async 

First it changes io-wq interfaces. It replaces {get,put}_work() with
free_work(), which guaranteed to be called exactly once. It also enforces
free_work() callback to be non-NULL.

io_uring follows the changes and instead of putting a submission reference
in io_put_req_async_completion(), it will be done in io_free_work(). As
removes io_get_work() with corresponding refcount_inc(), the ref balance
is maintained.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Pavel Begunkov 2020-03-04 16:14:12 +03:00 committed by Jens Axboe
parent f462fd36fc
commit e9fd939654
3 changed files with 27 additions and 39 deletions
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29
fs/io-wq.c
View File

@ -107,8 +107,7 @@ struct io_wq {
struct io_wqe **wqes;
unsigned long state;
get_work_fn *get_work;
put_work_fn *put_work;
free_work_fn *free_work;
struct task_struct *manager;
struct user_struct *user;
@ -509,16 +508,11 @@ get_next:
if (test_bit(IO_WQ_BIT_CANCEL, &wq->state))
work->flags |= IO_WQ_WORK_CANCEL;
if (wq->get_work)
wq->get_work(work);
old_work = work;
work->func(&work);
work = (old_work == work) ? NULL : work;
io_assign_current_work(worker, work);
if (wq->put_work)
wq->put_work(old_work);
wq->free_work(old_work);
if (hash != -1U) {
spin_lock_irq(&wqe->lock);
@ -749,14 +743,17 @@ static bool io_wq_can_queue(struct io_wqe *wqe, struct io_wqe_acct *acct,
return true;
}
static void io_run_cancel(struct io_wq_work *work)
static void io_run_cancel(struct io_wq_work *work, struct io_wqe *wqe)
{
struct io_wq *wq = wqe->wq;
do {
struct io_wq_work *old_work = work;
work->flags |= IO_WQ_WORK_CANCEL;
work->func(&work);
work = (work == old_work) ? NULL : work;
wq->free_work(old_work);
} while (work);
}
@ -773,7 +770,7 @@ static void io_wqe_enqueue(struct io_wqe *wqe, struct io_wq_work *work)
* It's close enough to not be an issue, fork() has the same delay.
*/
if (unlikely(!io_wq_can_queue(wqe, acct, work))) {
io_run_cancel(work);
io_run_cancel(work, wqe);
return;
}
@ -912,7 +909,7 @@ static enum io_wq_cancel io_wqe_cancel_cb_work(struct io_wqe *wqe,
spin_unlock_irqrestore(&wqe->lock, flags);
if (found) {
io_run_cancel(work);
io_run_cancel(work, wqe);
return IO_WQ_CANCEL_OK;
}
@ -987,7 +984,7 @@ static enum io_wq_cancel io_wqe_cancel_work(struct io_wqe *wqe,
spin_unlock_irqrestore(&wqe->lock, flags);
if (found) {
io_run_cancel(work);
io_run_cancel(work, wqe);
return IO_WQ_CANCEL_OK;
}
@ -1064,6 +1061,9 @@ struct io_wq *io_wq_create(unsigned bounded, struct io_wq_data *data)
int ret = -ENOMEM, node;
struct io_wq *wq;
if (WARN_ON_ONCE(!data->free_work))
return ERR_PTR(-EINVAL);
wq = kzalloc(sizeof(*wq), GFP_KERNEL);
if (!wq)
return ERR_PTR(-ENOMEM);
@ -1074,8 +1074,7 @@ struct io_wq *io_wq_create(unsigned bounded, struct io_wq_data *data)
return ERR_PTR(-ENOMEM);
}
wq->get_work = data->get_work;
wq->put_work = data->put_work;
wq->free_work = data->free_work;
/* caller must already hold a reference to this */
wq->user = data->user;
@ -1132,7 +1131,7 @@ err:
bool io_wq_get(struct io_wq *wq, struct io_wq_data *data)
{
if (data->get_work != wq->get_work || data->put_work != wq->put_work)
if (data->free_work != wq->free_work)
return false;
return refcount_inc_not_zero(&wq->use_refs);

6
fs/io-wq.h
View File

@ -81,14 +81,12 @@ struct io_wq_work {
*(work) = (struct io_wq_work){ .func = _func }; \
} while (0) \
typedef void (get_work_fn)(struct io_wq_work *);
typedef void (put_work_fn)(struct io_wq_work *);
typedef void (free_work_fn)(struct io_wq_work *);
struct io_wq_data {
struct user_struct *user;
get_work_fn *get_work;
put_work_fn *put_work;
free_work_fn *free_work;
};
struct io_wq *io_wq_create(unsigned bounded, struct io_wq_data *data);

31
fs/io_uring.c
View File

@ -1558,8 +1558,8 @@ static void io_put_req(struct io_kiocb *req)
io_free_req(req);
}
static void io_put_req_async_completion(struct io_kiocb *req,
struct io_wq_work **workptr)
static void io_steal_work(struct io_kiocb *req,
struct io_wq_work **workptr)
{
/*
* It's in an io-wq worker, so there always should be at least
@ -1569,7 +1569,6 @@ static void io_put_req_async_completion(struct io_kiocb *req,
* It also means, that if the counter dropped to 1, then there is
* no asynchronous users left, so it's safe to steal the next work.
*/
refcount_dec(&req->refs);
if (refcount_read(&req->refs) == 1) {
struct io_kiocb *nxt = NULL;
@ -2578,7 +2577,7 @@ static bool io_req_cancelled(struct io_kiocb *req)
if (req->work.flags & IO_WQ_WORK_CANCEL) {
req_set_fail_links(req);
io_cqring_add_event(req, -ECANCELED);
io_double_put_req(req);
io_put_req(req);
return true;
}
@ -2606,7 +2605,7 @@ static void io_fsync_finish(struct io_wq_work **workptr)
if (io_req_cancelled(req))
return;
__io_fsync(req);
io_put_req_async_completion(req, workptr);
io_steal_work(req, workptr);
}
static int io_fsync(struct io_kiocb *req, bool force_nonblock)
@ -2639,7 +2638,7 @@ static void io_fallocate_finish(struct io_wq_work **workptr)
if (io_req_cancelled(req))
return;
__io_fallocate(req);
io_put_req_async_completion(req, workptr);
io_steal_work(req, workptr);
}
static int io_fallocate_prep(struct io_kiocb *req,
@ -3006,7 +3005,7 @@ static void io_close_finish(struct io_wq_work **workptr)
/* not cancellable, don't do io_req_cancelled() */
__io_close_finish(req);
io_put_req_async_completion(req, workptr);
io_steal_work(req, workptr);
}
static int io_close(struct io_kiocb *req, bool force_nonblock)
@ -3452,7 +3451,7 @@ static void io_accept_finish(struct io_wq_work **workptr)
if (io_req_cancelled(req))
return;
__io_accept(req, false);
io_put_req_async_completion(req, workptr);
io_steal_work(req, workptr);
}
#endif
@ -4719,7 +4718,7 @@ static void io_wq_submit_work(struct io_wq_work **workptr)
io_put_req(req);
}
io_put_req_async_completion(req, workptr);
io_steal_work(req, workptr);
}
static int io_req_needs_file(struct io_kiocb *req, int fd)
@ -6105,21 +6104,14 @@ static int io_sqe_files_update(struct io_ring_ctx *ctx, void __user *arg,
return __io_sqe_files_update(ctx, &up, nr_args);
}
static void io_put_work(struct io_wq_work *work)
static void io_free_work(struct io_wq_work *work)
{
struct io_kiocb *req = container_of(work, struct io_kiocb, work);
/* Consider that io_put_req_async_completion() relies on this ref */
/* Consider that io_steal_work() relies on this ref */
io_put_req(req);
}
static void io_get_work(struct io_wq_work *work)
{
struct io_kiocb *req = container_of(work, struct io_kiocb, work);
refcount_inc(&req->refs);
}
static int io_init_wq_offload(struct io_ring_ctx *ctx,
struct io_uring_params *p)
{
@ -6130,8 +6122,7 @@ static int io_init_wq_offload(struct io_ring_ctx *ctx,
int ret = 0;
data.user = ctx->user;
data.get_work = io_get_work;
data.put_work = io_put_work;
data.free_work = io_free_work;
if (!(p->flags & IORING_SETUP_ATTACH_WQ)) {
/* Do QD, or 4 * CPUS, whatever is smallest */