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: Kent Overstreet <koverstreet@xxxxxxxxxx>
Cc: Zach Brown <zab@xxxxxxxxxx>
Cc: Felipe Balbi <balbi@xxxxxx>
Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Cc: Mark Fasheh <mfasheh@xxxxxxxx>
Cc: Joel Becker <jlbec@xxxxxxxxxxxx>
Cc: Rusty Russell <rusty@xxxxxxxxxxxxxxx>
Cc: Jens Axboe <axboe@xxxxxxxxx>
Cc: Asai Thambi S P <asamymuthupa@xxxxxxxxxx>
Cc: Selvan Mani <smani@xxxxxxxxxx>
Cc: Sam Bradshaw <sbradshaw@xxxxxxxxxx>
Cc: Jeff Moyer <jmoyer@xxxxxxxxxx>
Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: Benjamin LaHaise <bcrl@xxxxxxxxx>
---
drivers/usb/gadget/inode.c | 3 +--
fs/aio.c | 40 ++++++++++------------------------------
include/linux/aio.h | 2 +-
3 files changed, 12 insertions(+), 33 deletions(-)
diff --git a/drivers/usb/gadget/inode.c b/drivers/usb/gadget/inode.c
index 570c005..e02c1e0 100644
--- a/drivers/usb/gadget/inode.c
+++ b/drivers/usb/gadget/inode.c
@@ -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;
}
diff --git a/fs/aio.c b/fs/aio.c
index 93383b0..5e1b801 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -259,8 +259,7 @@ 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;
@@ -282,12 +281,10 @@ 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;
}
@@ -308,7 +305,6 @@ static void free_ioctx_rcu(struct rcu_head *head)
static void free_ioctx(struct kioctx *ctx)
{
struct aio_ring *ring;
- struct io_event res;
struct kiocb *req;
unsigned cpu, head, avail;
@@ -319,7 +315,7 @@ static void free_ioctx(struct kioctx *ctx)
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);
@@ -709,21 +705,6 @@ void aio_complete(struct kiocb *iocb, long res, long res2)
}
/*
- * 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->ctx_lock to prevent other code from messing with the tail
* pointer since we might be called from irq context.
@@ -775,7 +756,6 @@ 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);
@@ -1352,7 +1332,6 @@ 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;
@@ -1370,18 +1349,19 @@ 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;
}
put_ioctx(ctx);
diff --git a/include/linux/aio.h b/include/linux/aio.h
index 1bdf965..8c8dd1d 100644
--- a/include/linux/aio.h
+++ b/include/linux/aio.h
@@ -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;
--
1.8.2.1
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