Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net

[pandora-kernel.git] / drivers / oprofile / oprofilefs.c

diff --git a/drivers/oprofile/oprofilefs.c b/drivers/oprofile/oprofilefs.c
index d0de6cc..2f0aa0f 100644 (file)
--- 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);