linux-kernel - Re: [PATCH 4/4] module: Use the binary search for symbols resolution

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Message-ID: <BANLkTik9oekjUH6YXTda1P_dM231nEHQqA@mail.gmail.com>
Date:	Sat, 16 Apr 2011 22:32:08 +0800
From:	Wanlong Gao <wanlong.gao@...il.com>
To:	Alessio Igor Bogani <abogani@...nel.org>
Cc:	Rusty Russell <rusty@...tcorp.com.au>,
	Tim Abbott <tabbott@...lice.com>,
	Anders Kaseorg <andersk@...lice.com>,
	Jason Wessel <jason.wessel@...driver.com>,
	Tim Bird <tim.bird@...sony.com>,
	LKML <linux-kernel@...r.kernel.org>,
	Linux Embedded <linux-embedded@...r.kernel.org>
Subject: Re: [PATCH 4/4] module: Use the binary search for symbols resolution

On 4/16/11, Alessio Igor Bogani <abogani@...nel.org> wrote:
> Takes advantage of the order and locates symbols using binary search.
>
> This work was supported by a hardware donation from the CE Linux Forum.
>
> Signed-off-by: Alessio Igor Bogani <abogani@...nel.org>
> ---
>  kernel/module.c |   23 ++++++++++++++++-------
>  1 files changed, 16 insertions(+), 7 deletions(-)
>
> diff --git a/kernel/module.c b/kernel/module.c
> index b438b25..74a57c1 100644
> --- a/kernel/module.c
> +++ b/kernel/module.c
> @@ -57,6 +57,7 @@
>  #include <linux/kmemleak.h>
>  #include <linux/jump_label.h>
>  #include <linux/pfn.h>
> +#include <linux/bsearch.h>
>
>  #define CREATE_TRACE_POINTS
>  #include <trace/events/module.h>
> @@ -351,22 +352,30 @@ struct find_symbol_arg {
>  	const struct kernel_symbol *sym;
>  };
>
> +static int cmp_name(const void *va, const void *vb)
> +{
> +	const char *a;
> +	const struct kernel_symbol *b;
> +	a = va; b = vb;
> +	return strcmp(a, b->name);
> +}
> +
>  static bool find_symbol_in_symsearch(const struct symsearch *syms,
>  				     struct module *owner,
>  				     void *data)
>  {
>  	struct find_symbol_arg *fsa = data;
> +	struct kernel_symbol *sym;
>  	unsigned int symnum;
> -	int result;
>
> -	for (symnum = 0; symnum < syms->stop - syms->start; symnum++) {
> -		result = strcmp(fsa->name, syms->start[symnum].name);
> -		if (result == 0)
> -			break;
> -	}
> -	if (symnum >= syms->stop - syms->start)
> +	sym = bsearch(fsa->name, syms->start, syms->stop - syms->start,
As the bsearch func, why not change the syms->stop to syms->end ?
Hmm..Just a stupid suggestion.
Thanks
> +		sizeof(struct kernel_symbol), cmp_name);
> +
> +	if (sym == NULL)
>  		return false;
>
> +	symnum = sym - syms->start;
> +
>  	if (!fsa->gplok) {
>  		if (syms->licence == GPL_ONLY)
>  			return false;
> --
> 1.7.4.1
>
> --
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