Re: [2.6 patch][1/3] ipc/ BUG -> BUG_ON conversions

[Adrian Bunk <bunk@fs.tum.de>]

On Sat, Aug 28, 2004 at 12:05:10PM -0400, Kyle Moffett wrote:
> On Aug 28, 2004, at 11:15, Adrian Bunk wrote:
> >The patch below does BUG -> BUG_ON conversions in ipc/ .
> >--- linux-2.6.9-rc1-mm1-full-3.4/ipc/shm.c.old	2004-08-28 
> >15:55:28.000000000 +0200
> >+++ linux-2.6.9-rc1-mm1-full-3.4/ipc/shm.c	2004-08-28 
> >16:02:56.000000000 +0200
> >@@ -86,8 +86,7 @@
> > static inline void shm_inc (int id) {
> > 	struct shmid_kernel *shp;
> >
> >-	if(!(shp = shm_lock(id)))
> >-		BUG();
> >+	BUG_ON(!(shp = shm_lock(id)));
> 
> This won't work:
> 
> With debugging mode:
> if (unlikely(!(shp = shm_lock(id)))) BUG();
> 
> Without debugging mode:
> do { } while(0)

Where in 2.6.9-rc1-mm1 is this "Without debugging mode" defined?

> Anything you put in BUG_ON() must *NOT* have side effects.
>...

I'd have said exactly the same some time ago, but I was convinced by 
Arjan that if done correctly, a BUG_ON() with side effects is possible  
with no extra cost even if you want to make BUG configurably do nothing.

cu
Adrian

-- 

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       "Only a promise," Lao Er said.
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