drm_dp_aux_dev: switch to read_iter/write_iter

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

diff --git a/drivers/gpu/drm/drm_dp_aux_dev.c b/drivers/gpu/drm/drm_dp_aux_dev.c
index ec1ed94b239020f0a55425df9781f61003d15e3c..d34e5096887a4d9d0036967edfa3c7f9db8aa5b6 100644 (file)
--- a/drivers/gpu/drm/drm_dp_aux_dev.c
+++ b/drivers/gpu/drm/drm_dp_aux_dev.c
@@ -32,6 +32,7 @@
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/uaccess.h>
+#include <linux/uio.h>
 #include <drm/drm_dp_helper.h>
 #include <drm/drm_crtc.h>
 #include <drm/drmP.h>
@@ -140,101 +141,83 @@ static loff_t auxdev_llseek(struct file *file, loff_t offset, int whence)
        return fixed_size_llseek(file, offset, whence, AUX_MAX_OFFSET);
 }
 
-static ssize_t auxdev_read(struct file *file, char __user *buf, size_t count,
-                          loff_t *offset)
+static ssize_t auxdev_read_iter(struct kiocb *iocb, struct iov_iter *to)
 {
-       size_t bytes_pending, num_bytes_processed = 0;
-       struct drm_dp_aux_dev *aux_dev = file->private_data;
+       struct drm_dp_aux_dev *aux_dev = iocb->ki_filp->private_data;
+       loff_t pos = iocb->ki_pos;
        ssize_t res = 0;
 
        if (!atomic_inc_not_zero(&aux_dev->usecount))
                return -ENODEV;
 
-       bytes_pending = min((loff_t)count, AUX_MAX_OFFSET - (*offset));
-
-       if (!access_ok(VERIFY_WRITE, buf, bytes_pending)) {
-               res = -EFAULT;
-               goto out;
-       }
+       iov_iter_truncate(to, AUX_MAX_OFFSET - pos);
 
-       while (bytes_pending > 0) {
-               uint8_t localbuf[DP_AUX_MAX_PAYLOAD_BYTES];
-               ssize_t todo = min_t(size_t, bytes_pending, sizeof(localbuf));
+       while (iov_iter_count(to)) {
+               uint8_t buf[DP_AUX_MAX_PAYLOAD_BYTES];
+               ssize_t todo = min(iov_iter_count(to), sizeof(buf));
 
                if (signal_pending(current)) {
-                       res = num_bytes_processed ?
-                               num_bytes_processed : -ERESTARTSYS;
-                       goto out;
+                       res = -ERESTARTSYS;
+                       break;
                }
 
-               res = drm_dp_dpcd_read(aux_dev->aux, *offset, localbuf, todo);
-               if (res <= 0) {
-                       res = num_bytes_processed ? num_bytes_processed : res;
-                       goto out;
-               }
-               if (__copy_to_user(buf + num_bytes_processed, localbuf, res)) {
-                       res = num_bytes_processed ?
-                               num_bytes_processed : -EFAULT;
-                       goto out;
+               res = drm_dp_dpcd_read(aux_dev->aux, pos, buf, todo);
+               if (res <= 0)
+                       break;
+
+               if (copy_to_iter(buf, res, to) != res) {
+                       res = -EFAULT;
+                       break;
                }
-               bytes_pending -= res;
-               *offset += res;
-               num_bytes_processed += res;
-               res = num_bytes_processed;
+
+               pos += res;
        }
 
-out:
+       if (pos != iocb->ki_pos)
+               res = pos - iocb->ki_pos;
+       iocb->ki_pos = pos;
+
        atomic_dec(&aux_dev->usecount);
        wake_up_atomic_t(&aux_dev->usecount);
        return res;
 }
 
-static ssize_t auxdev_write(struct file *file, const char __user *buf,
-                           size_t count, loff_t *offset)
+static ssize_t auxdev_write_iter(struct kiocb *iocb, struct iov_iter *from)
 {
-       size_t bytes_pending, num_bytes_processed = 0;
-       struct drm_dp_aux_dev *aux_dev = file->private_data;
+       struct drm_dp_aux_dev *aux_dev = iocb->ki_filp->private_data;
+       loff_t pos = iocb->ki_pos;
        ssize_t res = 0;
 
        if (!atomic_inc_not_zero(&aux_dev->usecount))
                return -ENODEV;
 
-       bytes_pending = min((loff_t)count, AUX_MAX_OFFSET - *offset);
-
-       if (!access_ok(VERIFY_READ, buf, bytes_pending)) {
-               res = -EFAULT;
-               goto out;
-       }
+       iov_iter_truncate(from, AUX_MAX_OFFSET - pos);
 
-       while (bytes_pending > 0) {
-               uint8_t localbuf[DP_AUX_MAX_PAYLOAD_BYTES];
-               ssize_t todo = min_t(size_t, bytes_pending, sizeof(localbuf));
+       while (iov_iter_count(from)) {
+               uint8_t buf[DP_AUX_MAX_PAYLOAD_BYTES];
+               ssize_t todo = min(iov_iter_count(from), sizeof(buf));
 
                if (signal_pending(current)) {
-                       res = num_bytes_processed ?
-                               num_bytes_processed : -ERESTARTSYS;
-                       goto out;
+                       res = -ERESTARTSYS;
+                       break;
                }
 
-               if (__copy_from_user(localbuf,
-                                    buf + num_bytes_processed, todo)) {
-                       res = num_bytes_processed ?
-                               num_bytes_processed : -EFAULT;
-                       goto out;
+               if (!copy_from_iter_full(buf, todo, from)) {
+                       res = -EFAULT;
+                       break;
                }
 
-               res = drm_dp_dpcd_write(aux_dev->aux, *offset, localbuf, todo);
-               if (res <= 0) {
-                       res = num_bytes_processed ? num_bytes_processed : res;
-                       goto out;
-               }
-               bytes_pending -= res;
-               *offset += res;
-               num_bytes_processed += res;
-               res = num_bytes_processed;
+               res = drm_dp_dpcd_write(aux_dev->aux, pos, buf, todo);
+               if (res <= 0)
+                       break;
+
+               pos += res;
        }
 
-out:
+       if (pos != iocb->ki_pos)
+               res = pos - iocb->ki_pos;
+       iocb->ki_pos = pos;
+
        atomic_dec(&aux_dev->usecount);
        wake_up_atomic_t(&aux_dev->usecount);
        return res;
@@ -251,8 +234,8 @@ static int auxdev_release(struct inode *inode, struct file *file)
 static const struct file_operations auxdev_fops = {
        .owner          = THIS_MODULE,
        .llseek         = auxdev_llseek,
-       .read           = auxdev_read,
-       .write          = auxdev_write,
+       .read_iter      = auxdev_read_iter,
+       .write_iter     = auxdev_write_iter,
        .open           = auxdev_open,
        .release        = auxdev_release,
 };