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[PATCH 1/5] um: port: Move an assignment for the variable "fd" in port_wait()

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  [PATCH 1/5] um: port: Move an assignment for the variable "fd" in  port_wait() SF Markus Elfring <elfring@users.sourceforge.net> - 2017-01-18 23:00 +0100
    Re: [PATCH 1/5] um: port: Move an assignment for the variable "fd"  in port_wait() Jeff Dike <jdike@addtoit.com> - 2017-01-19 01:30 +0100

#1562205 — [PATCH 1/5] um: port: Move an assignment for the variable "fd" in port_wait()

From: Markus Elfring <elfring@users.sourceforge.net>
Date: Wed, 18 Jan 2017 21:40:29 +0100

A local variable was set to an error code in one case before a concrete
error situation was detected. Thus move the corresponding assignment into
an if branch to indicate a software failure there.

This issue was detected by using the Coccinelle software.

Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
---
 arch/um/drivers/port_kern.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/um/drivers/port_kern.c b/arch/um/drivers/port_kern.c
index 40ca5cc275e9..b2bbda21c5f3 100644
--- a/arch/um/drivers/port_kern.c
+++ b/arch/um/drivers/port_kern.c
@@ -230,10 +230,10 @@ int port_wait(void *data)
 
 	atomic_inc(&port->wait_count);
 	while (1) {
-		fd = -ERESTARTSYS;
-		if (wait_for_completion_interruptible(&port->done))
+		if (wait_for_completion_interruptible(&port->done)) {
+			fd = -ERESTARTSYS;
 			goto out;
-
+		}
 		spin_lock(&port->lock);
 
 		conn = list_entry(port->connections.next, struct connection,
-- 
2.11.0

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#1562328 — Re: [PATCH 1/5] um: port: Move an assignment for the variable "fd" in port_wait()

On Wed, Jan 18, 2017 at 10:56:17PM +0100, SF Markus Elfring wrote:
> diff --git a/arch/um/drivers/port_kern.c b/arch/um/drivers/port_kern.c
> index 40ca5cc275e9..b2bbda21c5f3 100644
> --- a/arch/um/drivers/port_kern.c
> +++ b/arch/um/drivers/port_kern.c
> @@ -230,10 +230,10 @@ int port_wait(void *data)
>  
>  	atomic_inc(&port->wait_count);
>  	while (1) {
> -		fd = -ERESTARTSYS;
> -		if (wait_for_completion_interruptible(&port->done))
> +		if (wait_for_completion_interruptible(&port->done)) {
> +			fd = -ERESTARTSYS;
>  			goto out;
> -
> +		}
>  		spin_lock(&port->lock);
>  
>  		conn = list_entry(port->connections.next, struct connection,
> -- 
> 2.11.0
>

The current code is pretty standard kernel coding style.  The inline
    fd = -ERESTARTSYS;
is likely free, or close to it, and I believe that having anything
besides a goto inside the if could make it significantly more
expensive.

				Jeff

-- 
Jeff Dike
AddToIt
978-254-0789 (o)
978-394-8986 (c)

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