oprofile: fix memory ordering
Nick Piggin [Thu, 23 Oct 2008 14:25:54 +0000 (16:25 +0200)]
Regular bitops don't work as locks on all architectures.

Also: can use non-atomic unlock as no concurrent stores to the word.

Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Robert Richter <robert.richter@amd.com>

drivers/oprofile/event_buffer.c

index d962ba0..191a320 100644 (file)
@@ -105,7 +105,7 @@ static int event_buffer_open(struct inode *inode, struct file *file)
        if (!capable(CAP_SYS_ADMIN))
                return -EPERM;
 
-       if (test_and_set_bit(0, &buffer_opened))
+       if (test_and_set_bit_lock(0, &buffer_opened))
                return -EBUSY;
 
        /* Register as a user of dcookies
@@ -129,7 +129,7 @@ static int event_buffer_open(struct inode *inode, struct file *file)
 fail:
        dcookie_unregister(file->private_data);
 out:
-       clear_bit(0, &buffer_opened);
+       __clear_bit_unlock(0, &buffer_opened);
        return err;
 }
 
@@ -141,7 +141,7 @@ static int event_buffer_release(struct inode *inode, struct file *file)
        dcookie_unregister(file->private_data);
        buffer_pos = 0;
        atomic_set(&buffer_ready, 0);
-       clear_bit(0, &buffer_opened);
+       __clear_bit_unlock(0, &buffer_opened);
        return 0;
 }