Rationalize fasync return values

Most fasync implementations do something like:

     return fasync_helper(...);

But fasync_helper() will return a positive value at times - a feature used
in at least one place.  Thus, a number of other drivers do:

     err = fasync_helper(...);
     if (err < 0)
             return err;
     return 0;

In the interests of consistency and more concise code, it makes sense to
map positive return values onto zero where ->fasync() is called.

Cc: Al Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

3 files changed, 6 insertions, 14 deletions

diff --git a/fs/fcntl.c b/fs/fcntl.c
index 431bb6459273..d865ca66ccba 100644
--- a/fs/fcntl.c
+++ b/fs/fcntl.c
@@ -184,6 +184,8 @@ static int setfl(int fd, struct file * filp, unsigned long arg)
 		error = filp->f_op->fasync(fd, filp, (arg & FASYNC) != 0);
 		if (error < 0)
 			goto out;
+		if (error > 0)
+			error = 0;
 	}
 	spin_lock(&filp->f_lock);
 	filp->f_flags = (arg & SETFL_MASK) | (filp->f_flags & ~SETFL_MASK);
diff --git a/fs/ioctl.c b/fs/ioctl.c
index e8e89edba576..ac2d47e43926 100644
--- a/fs/ioctl.c
+++ b/fs/ioctl.c
@@ -432,7 +432,7 @@ static int ioctl_fioasync(unsigned int fd, struct file *filp,
 		else
 			error = -ENOTTY;
 	}
-	return error;
+	return error < 0 ? error : 0;
 }
 
 static int ioctl_fsfreeze(struct file *filp)
diff --git a/fs/pipe.c b/fs/pipe.c
index 14f502b89cf5..94ad15967cf9 100644
--- a/fs/pipe.c
+++ b/fs/pipe.c
@@ -667,10 +667,7 @@ pipe_read_fasync(int fd, struct file *filp, int on)
 	retval = fasync_helper(fd, filp, on, &inode->i_pipe->fasync_readers);
 	mutex_unlock(&inode->i_mutex);
 
-	if (retval < 0)
-		return retval;
-
-	return 0;
+	return retval;
 }
 
 
@@ -684,10 +681,7 @@ pipe_write_fasync(int fd, struct file *filp, int on)
 	retval = fasync_helper(fd, filp, on, &inode->i_pipe->fasync_writers);
 	mutex_unlock(&inode->i_mutex);
 
-	if (retval < 0)
-		return retval;
-
-	return 0;
+	return retval;
 }
 
 
@@ -706,11 +700,7 @@ pipe_rdwr_fasync(int fd, struct file *filp, int on)
 			fasync_helper(-1, filp, 0, &pipe->fasync_readers);
 	}
 	mutex_unlock(&inode->i_mutex);
-
-	if (retval < 0)
-		return retval;
-
-	return 0;
+	return retval;
 }