linux-kernel - Re: [PATCH 3/3] module: use ZERO_OR_NULL

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Date:	Tue, 31 Jan 2012 09:42:52 +1030
From:	Rusty Russell <rusty@...tcorp.com.au>
To:	Dmitry Antipov <dmitry.antipov@...aro.org>
Cc:	linux-kernel@...r.kernel.org, linaro-dev@...ts.linaro.org,
	patches@...aro.org, Dmitry Antipov <dmitry.antipov@...aro.org>
Subject: Re: [PATCH 3/3] module: use ZERO_OR_NULL_PTR allocation pointer checking

On Mon, 30 Jan 2012 12:44:40 +0400, Dmitry Antipov <dmitry.antipov@...aro.org> wrote:
> Use ZERO_OR_NULL_PTR allocation pointer checking where allocation
> function may return ZERO_SIZE_PTR.
> 
> Signed-off-by: Dmitry Antipov <dmitry.antipov@...aro.org>
> ---
>  kernel/module.c |   12 ++++++------
>  1 files changed, 6 insertions(+), 6 deletions(-)
> 
> diff --git a/kernel/module.c b/kernel/module.c
> index 2c93276..5183f91 100644
> --- a/kernel/module.c
> +++ b/kernel/module.c
> @@ -438,7 +438,7 @@ static int percpu_modalloc(struct module *mod,
>  	}
>  
>  	mod->percpu = __alloc_reserved_percpu(size, align);
> -	if (!mod->percpu) {
> +	if (unlikely(ZERO_OR_NULL_PTR(mod->percpu))) {
>  		printk(KERN_WARNING
>  		       "%s: Could not allocate %lu bytes percpu data\n",
>  		       mod->name, size);

printk() is marked __cold.  You don't need unlikely() here.

> @@ -2652,7 +2652,7 @@ static int move_module(struct module *mod, struct load_info *info)
>  	 * after the module is initialized.
>  	 */
>  	kmemleak_ignore(ptr);
> -	if (!ptr && mod->init_size) {
> +	if (unlikely(ZERO_OR_NULL_PTR(ptr)) && mod->init_size) {
>  		module_free(mod, mod->module_core);
>  		return -ENOMEM;
>  	}

You want to just change this to:

        if (!ptr) {

Thanks,
Rusty.
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