diff options
Diffstat (limited to 'drivers/oprofile/oprofilefs.c')
| -rw-r--r-- | drivers/oprofile/oprofilefs.c | 11 |
1 files changed, 9 insertions, 2 deletions
diff --git a/drivers/oprofile/oprofilefs.c b/drivers/oprofile/oprofilefs.c index d0de6cc..2f0aa0f 100644 --- a/drivers/oprofile/oprofilefs.c +++ b/drivers/oprofile/oprofilefs.c @@ -60,6 +60,13 @@ ssize_t oprofilefs_ulong_to_user(unsigned long val, char __user *buf, size_t cou } +/* + * Note: If oprofilefs_ulong_from_user() returns 0, then *val remains + * unchanged and might be uninitialized. This follows write syscall + * implementation when count is zero: "If count is zero ... [and if] + * no errors are detected, 0 will be returned without causing any + * other effect." (man 2 write) + */ int oprofilefs_ulong_from_user(unsigned long *val, char const __user *buf, size_t count) { char tmpbuf[TMPBUFSIZE]; @@ -79,7 +86,7 @@ int oprofilefs_ulong_from_user(unsigned long *val, char const __user *buf, size_ raw_spin_lock_irqsave(&oprofilefs_lock, flags); *val = simple_strtoul(tmpbuf, NULL, 0); raw_spin_unlock_irqrestore(&oprofilefs_lock, flags); - return 0; + return count; } @@ -99,7 +106,7 @@ static ssize_t ulong_write_file(struct file *file, char const __user *buf, size_ return -EINVAL; retval = oprofilefs_ulong_from_user(&value, buf, count); - if (retval) + if (retval <= 0) return retval; retval = oprofile_set_ulong(file->private_data, value); |