Re: [PATCH] x86, olpc: Eliminate BUG_ON and memset after alloc_bootmem

[David Rientjes <rientjes@google.com>]

On Sat, 19 Jul 2014, Himangi Saraogi wrote:

> alloc_bootmem and related functions never return NULL and always return
> a zeroed region of memory.  Thus a BUG_ON the NULL test or memset after
> calls to these functions is unnecessary.
> 
> The following Coccinelle semantic patch was used for making the change:
> 
> @@
> expression E;
> statement S;
> @@
> 
> E = \(alloc_bootmem\|alloc_bootmem_low\|alloc_bootmem_pages\|alloc_bootmem_low_pages\)(...)
> ... when != E
> - BUG_ON (E == NULL);
> 
> @@
> expression E,E1;
> @@
> 
> E = \(alloc_bootmem\|alloc_bootmem_low\|alloc_bootmem_pages\|alloc_bootmem_low_pages\)(...)
> ... when != E
> - memset(E,0,E1);
> 
> Signed-off-by: Himangi Saraogi <himangi774@gmail.com>
> Acked-by: Julia Lawall <julia.lawall@lip6.fr>

Acked-by: David Rientjes <rientjes@google.com>

Many callers of alloc_bootmem() do not check for the return value because 
of this, there's no fallback available at this part in bootstrap so 
there's nothing else that can be done.