linux-kernel - Re: [PATCH v4 2/3] x86: pmc_atom: don't check for NULL twice

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Wed, 19 Nov 2014 12:36:06 +0100 (CET)
From:	Thomas Gleixner <tglx@...utronix.de>
To:	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
cc:	"H . Peter Anvin" <hpa@...ux.intel.com>, x86@...nel.org,
	Aubrey Li <aubrey.li@...ux.intel.com>,
	"Rafael J . Wysocki" <rafael.j.wysocki@...el.com>,
	"Kumar P, Mahesh" <mahesh.kumar.p@...el.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 2/3] x86: pmc_atom: don't check for NULL twice

On Wed, 12 Nov 2014, Andy Shevchenko wrote:

> debugfs_remove_recursive() is NULL-aware, thus, we may safely remove the check
> here. There is no need to assing NULL to variable since it will be not used
> anywhere.
> 
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
> Acked-by: Aubrey Li <aubrey.li@...ux.intel.com>
> ---
>  arch/x86/kernel/pmc_atom.c | 4 ----
>  1 file changed, 4 deletions(-)
> 
> diff --git a/arch/x86/kernel/pmc_atom.c b/arch/x86/kernel/pmc_atom.c
> index 19b8efa..bcc91ea 100644
> --- a/arch/x86/kernel/pmc_atom.c
> +++ b/arch/x86/kernel/pmc_atom.c
> @@ -202,11 +202,7 @@ static const struct file_operations pmc_sleep_tmr_ops = {
>  
>  static void pmc_dbgfs_unregister(struct pmc_dev *pmc)
>  {
> -	if (!pmc->dbgfs_dir)
> -		return;
> -
>  	debugfs_remove_recursive(pmc->dbgfs_dir);
> -	pmc->dbgfs_dir = NULL;
>  }

So while the patch is correct per se, the whole function is useless.

pmc_dbgfs_register()

	dir = debugfs_create_dir("pmc_atom", NULL);

	....
	if (!f)
		goto err;

	pmc->dbgfs_dir = dir;
	return 0;
err:
	pmc_dbgfs_unregister(pmc);

So pmc->dbgfs_dir is always NULL when this is called....

Aside of that, if DEBUGFS=n the code keeps pmc->regmap ioremapped for
no reason.

Looking deeper:

The pmc_power_off function is installed _BEFORE_ pmc_hw_reg_setup() is
called, which might not be called if the ioremap fails ....

Thanks,

	tglx


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/