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Commit bec68faa authored by Kent Overstreet's avatar Kent Overstreet Committed by Benjamin LaHaise
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aio: io_cancel() no longer returns the io_event 



Originally, io_event() was documented to return the io_event if
cancellation succeeded - the io_event wouldn't be delivered via the ring
buffer like it normally would.

But this isn't what the implementation was actually doing; the only
driver implementing cancellation, the usb gadget code, never returned an
io_event in its cancel function. And aio_complete() was recently changed
to no longer suppress event delivery if the kiocb had been cancelled.

This gets rid of the unused io_event argument to kiocb_cancel() and
kiocb->ki_cancel(), and changes io_cancel() to return -EINPROGRESS if
kiocb->ki_cancel() returned success.

Also tweak the refcounting in kiocb_cancel() to make more sense.

Signed-off-by: default avatarKent Overstreet <koverstreet@google.com>
Cc: Zach Brown <zab@redhat.com>
Cc: Felipe Balbi <balbi@ti.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Mark Fasheh <mfasheh@suse.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Asai Thambi S P <asamymuthupa@micron.com>
Cc: Selvan Mani <smani@micron.com>
Cc: Sam Bradshaw <sbradshaw@micron.com>
Cc: Jeff Moyer <jmoyer@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Benjamin LaHaise <bcrl@kvack.org>
Signed-off-by: default avatarBenjamin LaHaise <bcrl@kvack.org>
parent 723be6e3

drivers/usb/gadget/inode.c

+1 −2
Original line number Diff line number Diff line
@@ -524,7 +524,7 @@ struct kiocb_priv { 
	unsigned		actual;

};



static int ep_aio_cancel(struct kiocb *iocb, struct io_event *e)

static int ep_aio_cancel(struct kiocb *iocb)

{

	struct kiocb_priv	*priv = iocb->private;

	struct ep_data		*epdata;
@@ -540,7 +540,6 @@ static int ep_aio_cancel(struct kiocb *iocb, struct io_event *e) 
	// spin_unlock(&epdata->dev->lock);

	local_irq_enable();



	aio_put_req(iocb);

	return value;

}

fs/aio.c

+10 −30
Original line number Diff line number Diff line
@@ -358,8 +358,7 @@ void kiocb_set_cancel_fn(struct kiocb *req, kiocb_cancel_fn *cancel) 
}

EXPORT_SYMBOL(kiocb_set_cancel_fn);



static int kiocb_cancel(struct kioctx *ctx, struct kiocb *kiocb,

			struct io_event *res)

static int kiocb_cancel(struct kioctx *ctx, struct kiocb *kiocb)

{

	kiocb_cancel_fn *old, *cancel;

	int ret = -EINVAL;
@@ -381,12 +380,10 @@ static int kiocb_cancel(struct kioctx *ctx, struct kiocb *kiocb, 
	atomic_inc(&kiocb->ki_users);

	spin_unlock_irq(&ctx->ctx_lock);



	memset(res, 0, sizeof(*res));

	res->obj = (u64)(unsigned long)kiocb->ki_obj.user;

	res->data = kiocb->ki_user_data;

	ret = cancel(kiocb, res);

	ret = cancel(kiocb);



	spin_lock_irq(&ctx->ctx_lock);

	aio_put_req(kiocb);



	return ret;

}
@@ -408,7 +405,6 @@ static void free_ioctx(struct work_struct *work) 
{

	struct kioctx *ctx = container_of(work, struct kioctx, free_work);

	struct aio_ring *ring;

	struct io_event res;

	struct kiocb *req;

	unsigned cpu, head, avail;
@@ -419,7 +415,7 @@ static void free_ioctx(struct work_struct *work) 
				       struct kiocb, ki_list);



		list_del_init(&req->ki_list);

		kiocb_cancel(ctx, req, &res);

		kiocb_cancel(ctx, req);

	}



	spin_unlock_irq(&ctx->ctx_lock);
@@ -795,21 +791,6 @@ void aio_complete(struct kiocb *iocb, long res, long res2) 
		spin_unlock_irqrestore(&ctx->ctx_lock, flags);

	}



	/*

	 * cancelled requests don't get events, userland was given one

	 * when the event got cancelled.

	 */

	if (unlikely(xchg(&iocb->ki_cancel,

			  KIOCB_CANCELLED) == KIOCB_CANCELLED)) {

		/*

		 * Can't use the percpu reqs_available here - could race with

		 * free_ioctx()

		 */

		atomic_inc(&ctx->reqs_available);

		/* Still need the wake_up in case free_ioctx is waiting */

		goto put_rq;

	}



	/*

	 * Add a completion event to the ring buffer. Must be done holding

	 * ctx->completion_lock to prevent other code from messing with the tail
@@ -862,7 +843,6 @@ void aio_complete(struct kiocb *iocb, long res, long res2) 
	if (iocb->ki_eventfd != NULL)

		eventfd_signal(iocb->ki_eventfd, 1);



put_rq:

	/* everything turned out well, dispose of the aiocb. */

	aio_put_req(iocb);
@@ -1439,7 +1419,6 @@ static struct kiocb *lookup_kiocb(struct kioctx *ctx, struct iocb __user *iocb, 
SYSCALL_DEFINE3(io_cancel, aio_context_t, ctx_id, struct iocb __user *, iocb,

		struct io_event __user *, result)

{

	struct io_event res;

	struct kioctx *ctx;

	struct kiocb *kiocb;

	u32 key;
@@ -1457,18 +1436,19 @@ SYSCALL_DEFINE3(io_cancel, aio_context_t, ctx_id, struct iocb __user *, iocb, 


	kiocb = lookup_kiocb(ctx, iocb, key);

	if (kiocb)

		ret = kiocb_cancel(ctx, kiocb, &res);

		ret = kiocb_cancel(ctx, kiocb);

	else

		ret = -EINVAL;



	spin_unlock_irq(&ctx->ctx_lock);



	if (!ret) {

		/* Cancellation succeeded -- copy the result

		 * into the user's buffer.

		/*

		 * The result argument is no longer used - the io_event is

		 * always delivered via the ring buffer. -EINPROGRESS indicates

		 * cancellation is progress:

		 */

		if (copy_to_user(result, &res, sizeof(res)))

			ret = -EFAULT;

		ret = -EINPROGRESS;

	}



	percpu_ref_put(&ctx->users);

include/linux/aio.h

+1 −1
Original line number Diff line number Diff line
@@ -27,7 +27,7 @@ struct kiocb; 
 */

#define KIOCB_CANCELLED		((void *) (~0ULL))



typedef int (kiocb_cancel_fn)(struct kiocb *, struct io_event *);

typedef int (kiocb_cancel_fn)(struct kiocb *);



struct kiocb {

	atomic_t		ki_users;