[patch] 2.5.9 remove warnings

[patch] 2.5.9 remove warnings

[Keith Owens]

exit.c:40: warning: passing arg 1 of `__builtin_expect' makes integer from pointer without a cast

Index: 9.2/kernel/exit.c
--- 9.2/kernel/exit.c Tue, 23 Apr 2002 11:21:19 +1000 kaos (linux-2.5/w/d/25_exit.c 1.11.1.4 644)
+++ 9.2(w)/kernel/exit.c Tue, 23 Apr 2002 13:37:06 +1000 kaos (linux-2.5/w/d/25_exit.c 1.11.1.4 644)
@@ -37,7 +37,7 @@ static inline void __unhash_process(stru
 	list_del(&p->thread_group);
 	p->pid = 0;
 	proc_dentry = p->proc_dentry;
-	if (unlikely(proc_dentry)) {
+	if (unlikely(proc_dentry != NULL)) {
 		spin_lock(&dcache_lock);
 		if (!list_empty(&proc_dentry->d_hash)) {
 			dget_locked(proc_dentry);
@@ -47,7 +47,7 @@ static inline void __unhash_process(stru
 		spin_unlock(&dcache_lock);
 	}
 	write_unlock_irq(&tasklist_lock);
-	if (unlikely(proc_dentry)) {
+	if (unlikely(proc_dentry != NULL)) {
 		shrink_dcache_parent(proc_dentry);
 		dput(proc_dentry);
 	}

Re: [patch] 2.5.9 remove warnings

[Daniel Phillips]

On Tuesday 23 April 2002 05:39, Keith Owens wrote:
> exit.c:40: warning: passing arg 1 of `__builtin_expect' makes integer from pointer without a cast

> -	if (unlikely(proc_dentry)) {
> +	if (unlikely(proc_dentry != NULL)) {

Have you checked to see if this produces the same code?  To be on the safe
side:

+	if (unlikely((ulong) proc_dentry)) {

-- 
Daniel

Re: [patch] 2.5.9 remove warnings

[Andrew Morton]

Keith Owens wrote:
> 
> ...
> @@ -47,7 +47,7 @@ static inline void __unhash_process(stru
>                 spin_unlock(&dcache_lock);
>         }
>         write_unlock_irq(&tasklist_lock);
> -       if (unlikely(proc_dentry)) {
> +       if (unlikely(proc_dentry != NULL)) {
>                 shrink_dcache_parent(proc_dentry);
>                 dput(proc_dentry);
>         }

Is it not possible to fix it for all time?

--- linux-2.5.9/include/linux/compiler.h	Sun Apr 14 15:45:08 2002
+++ 25/include/linux/compiler.h	Tue Apr 23 11:27:37 2002
@@ -10,8 +10,8 @@
 #define __builtin_expect(x, expected_value) (x)
 #endif
 
-#define likely(x)	__builtin_expect((x),1)
-#define unlikely(x)	__builtin_expect((x),0)
+#define likely(x)	__builtin_expect((x) != 0, 1)
+#define unlikely(x)	__builtin_expect((x) != 0, 0)
 
 /* This macro obfuscates arithmetic on a variable address so that gcc
    shouldn't recognize the original var, and make assumptions about it */

(Interestingly, this patch shrinks my kernel by 32 bytes.  hmm.)

BTW, it would be very useful if someone could invert the sense of
`likely' and `unlikely', so they always say the *wrong* thing, and
then actually demonstrate some real-world slowdown.  coz if this
can't be done, why are we putting up with the visual clutter?

-

Re: [patch] 2.5.9 remove warnings

[Kasper Dupont]

Andrew Morton wrote:
> 
> Is it not possible to fix it for all time?
> 
> --- linux-2.5.9/include/linux/compiler.h        Sun Apr 14 15:45:08 2002
> +++ 25/include/linux/compiler.h Tue Apr 23 11:27:37 2002
> @@ -10,8 +10,8 @@
>  #define __builtin_expect(x, expected_value) (x)
>  #endif
> 
> -#define likely(x)      __builtin_expect((x),1)
> -#define unlikely(x)    __builtin_expect((x),0)
> +#define likely(x)      __builtin_expect((x) != 0, 1)
> +#define unlikely(x)    __builtin_expect((x) != 0, 0)
> 
>  /* This macro obfuscates arithmetic on a variable address so that gcc
>     shouldn't recognize the original var, and make assumptions about it */

Wouldn't "!!(x)" make more sense here than "(x) != 0"?
(I don't like comparing pointers with integers.)

-- 
Kasper Dupont -- der bruger for meget tid på usenet.
For sending spam use mailto:razor-report@daimi.au.dk

Re: [patch] 2.5.9 remove warnings

[Ingo Oeser]

On Tue, Apr 23, 2002 at 11:08:08PM +0200, Kasper Dupont wrote:
> Wouldn't "!!(x)" make more sense here than "(x) != 0"?
> (I don't like comparing pointers with integers.)

No, == 0 means, that the pointer is invalid, so != 0 means, the
pointer is valid. You can find this in the C99-Standard at least.

So, this is perfectly normal ;-)

Regards

Ingo Oeser
-- 
Science is what we can tell a computer. Art is everything else. --- D.E.Knuth