soc: aspeed: fix a ternary sign expansion bug

[ Upstream commit 5ffa828534036348fa90fb3079ccc0972d202c4a ]

The intent here was to return negative error codes but it actually
returns positive values.  The problem is that type promotion with
ternary operations is quite complicated.

"ret" is an int.  "copied" is a u32.  And the snoop_file_read() function
returns long.  What happens is that "ret" is cast to u32 and becomes
positive then it's cast to long and it's still positive.

Fix this by removing the ternary so that "ret" is type promoted directly
to long.

Fixes: 3772e5da4454 ("drivers/misc: Aspeed LPC snoop output using misc chardev")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Joel Stanley <joel@jms.id.au>
Reviewed-by: Patrick Venture <venture@google.com>
Link: https://lore.kernel.org/r/YIE90PSXsMTa2Y8n@mwanda
Link: https://lore.kernel.org/r/20210423000919.1249474-1-joel@jms.id.au'
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/misc/aspeed-lpc-snoop.c b/drivers/misc/aspeed-lpc-snoop.c
index b4a776bf44bc56f72b26a0b1ec3a2fab8d19cd91..e2cb0b9607d113539fad0f9575c2d32b104cbce1 100644 (file)
--- a/drivers/misc/aspeed-lpc-snoop.c
+++ b/drivers/misc/aspeed-lpc-snoop.c
@@ -99,8 +99,10 @@ static ssize_t snoop_file_read(struct file *file, char __user *buffer,
                        return -EINTR;
        }
        ret = kfifo_to_user(&chan->fifo, buffer, count, &copied);
+       if (ret)
+               return ret;
 
-       return ret ? ret : copied;
+       return copied;
 }
 
 static __poll_t snoop_file_poll(struct file *file,