[PATCH 1/4] PCI: Align proc_bus_pci_write() with pci_write_config()

[Ziming Du <duziming2@huawei.com>]

proc_bus_pci_write() and pci_write_config() implement essentially the
same functionality. To improve consistency across the PCI subsystem,
align the implementation in procfs with the sysfs counterpart.

Specifically:
  - Use dev->cfg_size directly insted of assigning it to 'size'.
  - Rename the variable 'pos' to 'off' and replace 'cnt' with 'size'.
  - Remove the redundant bounds check `if (nbytes >= size)`.

No functional change intended.

Suggested-by: Bjorn Helgaas <helgaas@kernel.org>
Signed-off-by: Ziming Du <duziming2@huawei.com>
---
 drivers/pci/proc.c | 57 +++++++++++++++++++++++-----------------------
 1 file changed, 28 insertions(+), 29 deletions(-)

diff --git a/drivers/pci/proc.c b/drivers/pci/proc.c
index ce36e35681e8..ff5e4980c99c 100644
--- a/drivers/pci/proc.c
+++ b/drivers/pci/proc.c
@@ -113,73 +113,72 @@ static ssize_t proc_bus_pci_write(struct file *file, const char __user *buf,
 {
 	struct inode *ino = file_inode(file);
 	struct pci_dev *dev = pde_data(ino);
-	int pos = *ppos;
-	int size = dev->cfg_size;
-	int cnt, ret;
+	int off = *ppos;
+	unsigned int size = nbytes;
+	int ret;
 
 	ret = security_locked_down(LOCKDOWN_PCI_ACCESS);
 	if (ret)
 		return ret;
 
-	if (pos >= size)
+	if (off >= dev->cfg_size)
 		return 0;
-	if (nbytes >= size)
+	if (off + size > dev->cfg_size) {
+		size = dev->cfg_size - off;
 		nbytes = size;
-	if (pos + nbytes > size)
-		nbytes = size - pos;
-	cnt = nbytes;
+	}
 
-	if (!access_ok(buf, cnt))
+	if (!access_ok(buf, size))
 		return -EINVAL;
 
 	pci_config_pm_runtime_get(dev);
 
-	if ((pos & 1) && cnt) {
+	if ((off & 1) && size) {
 		unsigned char val;
 		__get_user(val, buf);
-		pci_user_write_config_byte(dev, pos, val);
+		pci_user_write_config_byte(dev, off, val);
 		buf++;
-		pos++;
-		cnt--;
+		off++;
+		size--;
 	}
 
-	if ((pos & 3) && cnt > 2) {
+	if ((off & 3) && size > 2) {
 		__le16 val;
 		__get_user(val, (__le16 __user *) buf);
-		pci_user_write_config_word(dev, pos, le16_to_cpu(val));
+		pci_user_write_config_word(dev, off, le16_to_cpu(val));
 		buf += 2;
-		pos += 2;
-		cnt -= 2;
+		off += 2;
+		size -= 2;
 	}
 
-	while (cnt >= 4) {
+	while (size >= 4) {
 		__le32 val;
 		__get_user(val, (__le32 __user *) buf);
-		pci_user_write_config_dword(dev, pos, le32_to_cpu(val));
+		pci_user_write_config_dword(dev, off, le32_to_cpu(val));
 		buf += 4;
-		pos += 4;
-		cnt -= 4;
+		off += 4;
+		size -= 4;
 	}
 
-	if (cnt >= 2) {
+	if (size >= 2) {
 		__le16 val;
 		__get_user(val, (__le16 __user *) buf);
-		pci_user_write_config_word(dev, pos, le16_to_cpu(val));
+		pci_user_write_config_word(dev, off, le16_to_cpu(val));
 		buf += 2;
-		pos += 2;
-		cnt -= 2;
+		off += 2;
+		size -= 2;
 	}
 
-	if (cnt) {
+	if (size) {
 		unsigned char val;
 		__get_user(val, buf);
-		pci_user_write_config_byte(dev, pos, val);
-		pos++;
+		pci_user_write_config_byte(dev, off, val);
+		off++;
 	}
 
 	pci_config_pm_runtime_put(dev);
 
-	*ppos = pos;
+	*ppos = off;
 	i_size_write(ino, dev->cfg_size);
 	return nbytes;
 }
-- 
2.43.0