2005-03-16 23:38:26

by Jesper Juhl

Subject: [PATCH] net, ipv6: remove redundant NULL checks before kfree in ip6_flowlabel.c

kfree() has no problems dealing with NULL pointers, so wrapping checks for
null round calls to it is redundant. This patch gets rid of two such
checks in net/ipv6/ip6_flowlabel.c

I considered also rewriting the
if (fl)
fl_free(fl);
bit as simply fl_free(fl) as well, but that if() potentially saves two
calls to kfree() inside fl_free as well as the call to fl_free itself, so
I guess that's worth the if().

Please consider applying.


Signed-off-by: Jesper Juhl <[email protected]>

diff -up linux-2.6.11-mm4-orig/net/ipv6/ip6_flowlabel.c linux-2.6.11-mm4/net/ipv6/ip6_flowlabel.c
--- linux-2.6.11-mm4-orig/net/ipv6/ip6_flowlabel.c 2005-03-02 08:37:50.000000000 +0100
+++ linux-2.6.11-mm4/net/ipv6/ip6_flowlabel.c 2005-03-17 00:23:30.000000000 +0100
@@ -87,8 +87,7 @@ static struct ip6_flowlabel * fl_lookup(

static void fl_free(struct ip6_flowlabel *fl)
{
- if (fl->opt)
- kfree(fl->opt);
+ kfree(fl->opt);
kfree(fl);
}

@@ -553,8 +552,7 @@ release:
done:
if (fl)
fl_free(fl);
- if (sfl1)
- kfree(sfl1);
+ kfree(sfl1);
return err;
}




--
Jesper Juhl

PS. Please CC me on replies from lists other than linux-kernel

2005-03-17 02:53:11

by YOSHIFUJI Hideaki

Subject: Re: [PATCH] net, ipv6: remove redundant NULL checks before kfree in ip6_flowlabel.c

In article <[email protected]> (at Thu, 17 Mar 2005 00:36:35 +0100 (CET)), Jesper Juhl <[email protected]> says:

> I considered also rewriting the
> if (fl)
> fl_free(fl);
> bit as simply fl_free(fl) as well, but that if() potentially saves two
> calls to kfree() inside fl_free as well as the call to fl_free itself, so
> I guess that's worth the if().

I don't mind calling kfree twice itself (because that function is not
so performance critical), but fl_free(NULL) is out because
if fl is NULL, kfree(fl->opt) is out.

So, what do you think of checking fl inside fl_free like this?

We can even make fl_free inline and check as following:
if (fl) {
kfree(fl->opt);
kfree(fl);
}

Based on patch from Jesper Juhl <[email protected]>.

David?

Signed-off-by: Hideaki YOSHIFUJI <[email protected]>

===== net/ipv6/ip6_flowlabel.c 1.18 vs edited =====
--- 1.18/net/ipv6/ip6_flowlabel.c 2005-01-14 13:41:06 +09:00
+++ edited/net/ipv6/ip6_flowlabel.c 2005-03-17 11:23:32 +09:00
@@ -87,7 +87,7 @@

static void fl_free(struct ip6_flowlabel *fl)
{
- if (fl->opt)
+ if (fl)
kfree(fl->opt);
kfree(fl);
}
@@ -351,8 +351,7 @@
return fl;

done:
- if (fl)
- fl_free(fl);
+ fl_free(fl);
*err_p = err;
return NULL;
}
@@ -551,10 +550,8 @@
}

done:
- if (fl)
- fl_free(fl);
- if (sfl1)
- kfree(sfl1);
+ fl_free(fl);
+ kfree(sfl1);
return err;
}


--
Hideaki YOSHIFUJI @ USAGI Project <[email protected]>
GPG FP: 9022 65EB 1ECF 3AD1 0BDF 80D8 4807 F894 E062 0EEA