x86: msr: correct return value on partial operations
Return the correct return value when the MSR driver partially
completes a request (we should return the number of bytes actually
read or written, instead of the error code.)
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
diff --git a/arch/x86/kernel/msr.c b/arch/x86/kernel/msr.c
index 9c34a10..2e2af5d 100644
--- a/arch/x86/kernel/msr.c
+++ b/arch/x86/kernel/msr.c
@@ -72,7 +72,8 @@
u32 data[2];
u32 reg = *ppos;
int cpu = iminor(file->f_path.dentry->d_inode);
- int err;
+ int err = 0;
+ ssize_t bytes = 0;
if (count % 8)
return -EINVAL; /* Invalid chunk size */
@@ -82,14 +83,17 @@
if (err) {
if (err == -EFAULT) /* Fix idiotic error code */
err = -EIO;
- return err;
+ break;
}
- if (copy_to_user(tmp, &data, 8))
- return -EFAULT;
+ if (copy_to_user(tmp, &data, 8)) {
+ err = -EFAULT;
+ break;
+ }
tmp += 2;
+ bytes += 8;
}
- return ((char __user *)tmp) - buf;
+ return bytes ? bytes : err;
}
static ssize_t msr_write(struct file *file, const char __user *buf,
@@ -99,24 +103,28 @@
u32 data[2];
u32 reg = *ppos;
int cpu = iminor(file->f_path.dentry->d_inode);
- int err;
+ int err = 0;
+ ssize_t bytes = 0;
if (count % 8)
return -EINVAL; /* Invalid chunk size */
for (; count; count -= 8) {
- if (copy_from_user(&data, tmp, 8))
- return -EFAULT;
+ if (copy_from_user(&data, tmp, 8)) {
+ err = -EFAULT;
+ break;
+ }
err = wrmsr_safe_on_cpu(cpu, reg, data[0], data[1]);
if (err) {
if (err == -EFAULT) /* Fix idiotic error code */
err = -EIO;
- return err;
+ break;
}
tmp += 2;
+ bytes += 8;
}
- return ((char __user *)tmp) - buf;
+ return bytes ? bytes : err;
}
static int msr_open(struct inode *inode, struct file *file)