This removes the only in-tree user of aio retry and cancellation. This
will let us remove code from the aio core.
Removing retry is relatively easy as the USB gadget wasn't using it to
retry IOs at all. It always fully submitted the IO in the context of
the initial io_submit() call. It only used the AIO retry facility to
get the submitter's mm context for copying the result of a read back to
user space. This is easy to implement with use_mm() and a work struct,
much like kvm does with async_pf_execute() for get_user_pages().
The removal of cancelation is not quite so tidy. It simply stops the
ability to cancel pending IOs. This is safe in principle because
applications always had to deal with the possibility of the IO finishing
before the cancel was attempted. My hope is that cancelation is not
heavily used.
Signed-off-by: Zach Brown <zab@xxxxxxxxxx>
---
drivers/usb/gadget/inode.c | 63 +++++++++++++++++++++++-----------------------
1 file changed, 32 insertions(+), 31 deletions(-)
diff --git a/drivers/usb/gadget/inode.c b/drivers/usb/gadget/inode.c
index 76494ca..20b29bb 100644
--- a/drivers/usb/gadget/inode.c
+++ b/drivers/usb/gadget/inode.c
@@ -24,6 +24,7 @@
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/poll.h>
+#include <linux/mmu_context.h>
#include <linux/device.h>
#include <linux/moduleparam.h>
@@ -514,42 +515,21 @@ static long ep_ioctl(struct file *fd, unsigned code, unsigned long value)
struct kiocb_priv {
struct usb_request *req;
struct ep_data *epdata;
+ struct kiocb *iocb;
+ struct mm_struct *mm;
+ struct work_struct work;
void *buf;
const struct iovec *iv;
unsigned long nr_segs;
unsigned actual;
};
-static int ep_aio_cancel(struct kiocb *iocb, struct io_event *e)
+static ssize_t ep_copy_to_user(struct kiocb_priv *priv)
{
- struct kiocb_priv *priv = iocb->private;
- struct ep_data *epdata;
- int value;
-
- local_irq_disable();
- epdata = priv->epdata;
- // spin_lock(&epdata->dev->lock);
- kiocbSetCancelled(iocb);
- if (likely(epdata && epdata->ep && priv->req))
- value = usb_ep_dequeue (epdata->ep, priv->req);
- else
- value = -EINVAL;
- // spin_unlock(&epdata->dev->lock);
- local_irq_enable();
-
- aio_put_req(iocb);
- return value;
-}
-
-static ssize_t ep_aio_read_retry(struct kiocb *iocb)
-{
- struct kiocb_priv *priv = iocb->private;
ssize_t len, total;
void *to_copy;
int i;
- /* we "retry" to get the right mm context for this: */
-
/* copy stuff into user buffers */
total = priv->actual;
len = 0;
@@ -569,9 +549,26 @@ static ssize_t ep_aio_read_retry(struct kiocb *iocb)
if (total == 0)
break;
}
+
+ return len;
+}
+
+static void ep_user_copy_worker(struct work_struct *work)
+{
+ struct kiocb_priv *priv = container_of(work, struct kiocb_priv, work);
+ struct mm_struct *mm = priv->mm;
+ struct kiocb *iocb = priv->iocb;
+ size_t ret;
+
+ use_mm(mm);
+ ret = ep_copy_to_user(priv);
+ unuse_mm(mm);
+ mmdrop(mm);
+
+ aio_complete(iocb, ret, ret);
+
kfree(priv->buf);
kfree(priv);
- return len;
}
static void ep_aio_complete(struct usb_ep *ep, struct usb_request *req)
@@ -591,20 +588,21 @@ static void ep_aio_complete(struct usb_ep *ep, struct usb_request *req)
*/
if (priv->iv == NULL || unlikely(req->actual == 0)) {
kfree(req->buf);
+ mmdrop(priv->mm);
kfree(priv);
iocb->private = NULL;
/* aio_complete() reports bytes-transferred _and_ faults */
aio_complete(iocb, req->actual ? req->actual : req->status,
req->status);
} else {
- /* retry() won't report both; so we hide some faults */
+ /* ep_copy_to_user() won't report both; we hide some faults */
if (unlikely(0 != req->status))
DBG(epdata->dev, "%s fault %d len %d\n",
ep->name, req->status, req->actual);
priv->buf = req->buf;
priv->actual = req->actual;
- kick_iocb(iocb);
+ schedule_work(&priv->work);
}
spin_unlock(&epdata->dev->lock);
@@ -634,8 +632,10 @@ fail:
return value;
}
iocb->private = priv;
+ priv->iocb = iocb;
priv->iv = iv;
priv->nr_segs = nr_segs;
+ INIT_WORK(&priv->work, ep_user_copy_worker);
value = get_ready_ep(iocb->ki_filp->f_flags, epdata);
if (unlikely(value < 0)) {
@@ -643,10 +643,11 @@ fail:
goto fail;
}
- iocb->ki_cancel = ep_aio_cancel;
get_ep(epdata);
priv->epdata = epdata;
priv->actual = 0;
+ priv->mm = current->mm;
+ atomic_inc(&priv->mm->mm_count);
/* each kiocb is coupled to one usb_request, but we can't
* allocate or submit those if the host disconnected.
@@ -672,10 +673,11 @@ fail:
mutex_unlock(&epdata->lock);
if (unlikely(value)) {
+ mmdrop(priv->mm);
kfree(priv);
put_ep(epdata);
} else
- value = (iv ? -EIOCBRETRY : -EIOCBQUEUED);
+ value = -EIOCBQUEUED;
return value;
}
@@ -693,7 +695,6 @@ ep_aio_read(struct kiocb *iocb, const struct iovec *iov,
if (unlikely(!buf))
return -ENOMEM;
- iocb->ki_retry = ep_aio_read_retry;
return ep_aio_rwtail(iocb, buf, iocb->ki_left, epdata, iov, nr_segs);
}
--
1.7.11.4
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