diff mbox

batman-adv: Use kasprintf

Message ID 1403982781.9064.33.camel@joe-AO725
State RFC, archived
Delegated to: David Miller
Headers show

Commit Message

Joe Perches June 28, 2014, 7:13 p.m. UTC 
On Sun, 2014-06-29 at 00:06 +0530, Himangi Saraogi wrote:
> kasprintf combines kmalloc and sprintf, and takes care of the size
> calculation itself.

Nice.  A small conversion to remove
unnecessary initializations, avoid calling
kfree with known NULL pointers, and save a
few bytes of code space woud be:
---
 net/batman-adv/sysfs.c | 15 ++++++++-------
 1 file changed, 8 insertions(+), 7 deletions(-)



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Comments

Antonio Quartulli June 28, 2014, 7:49 p.m. UTC | #1 
Hi all,

On 28/06/14 21:13, Joe Perches wrote:
> diff --git a/net/batman-adv/sysfs.c b/net/batman-adv/sysfs.c
> index f40cb04..d6fba94 100644
> --- a/net/batman-adv/sysfs.c
> +++ b/net/batman-adv/sysfs.c
> @@ -896,7 +896,7 @@ int batadv_throw_uevent(struct batadv_priv *bat_priv, enum batadv_uev_type type,
>  {
>  	int ret = -ENOMEM;
>  	struct kobject *bat_kobj;
> -	char *uevent_env[4] = { NULL, NULL, NULL, NULL };
> +	char *uevent_env[3];


Joe, why are you shortening this? kobject_uevent_env() expect a
NULL-terminating array (that is the forth cell).

...

>  
>  	ret = kobject_uevent_env(bat_kobj, KOBJ_CHANGE, uevent_env);

And how is this change reducing the code space?

For what concerns the labels, we use this pattern mostly all over the
code: one single label/exit-point with the related NULL checks. Do you
think that we can improve something by changing this? (I am not talking
about the fastpath here).


Cheers,
Julia Lawall June 28, 2014, 8:14 p.m. UTC | #2 
On Sat, 28 Jun 2014, Antonio Quartulli wrote:

> Hi all,
> 
> On 28/06/14 21:13, Joe Perches wrote:
> > diff --git a/net/batman-adv/sysfs.c b/net/batman-adv/sysfs.c
> > index f40cb04..d6fba94 100644
> > --- a/net/batman-adv/sysfs.c
> > +++ b/net/batman-adv/sysfs.c
> > @@ -896,7 +896,7 @@ int batadv_throw_uevent(struct batadv_priv *bat_priv, enum batadv_uev_type type,
> >  {
> >  	int ret = -ENOMEM;
> >  	struct kobject *bat_kobj;
> > -	char *uevent_env[4] = { NULL, NULL, NULL, NULL };
> > +	char *uevent_env[3];
> 
> 
> Joe, why are you shortening this? kobject_uevent_env() expect a
> NULL-terminating array (that is the forth cell).
> 
> ...
> 
> >  
> >  	ret = kobject_uevent_env(bat_kobj, KOBJ_CHANGE, uevent_env);
> 
> And how is this change reducing the code space?
> 
> For what concerns the labels, we use this pattern mostly all over the
> code: one single label/exit-point with the related NULL checks. Do you
> think that we can improve something by changing this? (I am not talking
> about the fastpath here).

Most of the kernel uses specific labels for each possible failure.
From my selfish point of view, it makes the code easier to analyze and 
understand, because what is done at the exit label is only what needs to 
be done.

julia
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diff mbox

Patch

diff --git a/net/batman-adv/sysfs.c b/net/batman-adv/sysfs.c
index f40cb04..d6fba94 100644
--- a/net/batman-adv/sysfs.c
+++ b/net/batman-adv/sysfs.c
@@ -896,7 +896,7 @@  int batadv_throw_uevent(struct batadv_priv *bat_priv, enum batadv_uev_type type,
 {
 	int ret = -ENOMEM;
 	struct kobject *bat_kobj;
-	char *uevent_env[4] = { NULL, NULL, NULL, NULL };
+	char *uevent_env[3];
 
 	bat_kobj = &bat_priv->soft_iface->dev.kobj;
 
@@ -910,22 +910,23 @@  int batadv_throw_uevent(struct batadv_priv *bat_priv, enum batadv_uev_type type,
 				  "%s%s", BATADV_UEV_ACTION_VAR,
 				  batadv_uev_action_str[action]);
 	if (!uevent_env[1])
-		goto out;
+		goto out0;
 
 	/* If the event is DEL, ignore the data field */
 	if (action != BATADV_UEV_DEL) {
 		uevent_env[2] = kasprintf(GFP_ATOMIC,
 					  "%s%s", BATADV_UEV_DATA_VAR, data);
 		if (!uevent_env[2])
-			goto out;
+			goto out1;
 	}
 
 	ret = kobject_uevent_env(bat_kobj, KOBJ_CHANGE, uevent_env);
-out:
-	kfree(uevent_env[0]);
-	kfree(uevent_env[1]);
 	kfree(uevent_env[2]);
-
+out1:
+	kfree(uevent_env[1]);
+out0:
+	kfree(uevent_env[0]);
+out:
 	if (ret)
 		batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
 			   "Impossible to send uevent for (%s,%s,%s) event (err: %d)\n",