linux-kernel - Re: [PATCH 05/12] staging: lustre: Optimize error handling in class_register

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Date:	Tue, 26 Jul 2016 15:11:40 -0400
From:	Oleg Drokin <oleg.drokin@...el.com>
To:	SF Markus Elfring <elfring@...rs.sourceforge.net>
Cc:	<devel@...verdev.osuosl.org>, <lustre-devel@...ts.lustre.org>,
	"Andreas Dilger" <andreas.dilger@...el.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	LKML <linux-kernel@...r.kernel.org>,
	<kernel-janitors@...r.kernel.org>,
	Julia Lawall <julia.lawall@...6.fr>,
	Bhumika Goyal <bhumirks@...il.com>
Subject: Re: [PATCH 05/12] staging: lustre: Optimize error handling in class_register_type()


On Jul 26, 2016, at 3:05 PM, SF Markus Elfring wrote:

> From: Markus Elfring <elfring@...rs.sourceforge.net>
> Date: Tue, 26 Jul 2016 14:23:23 +0200
> 
> Return a constant error code without storing it in the local variable "rc"
> after a failed memory allocation at the beginning of this function.
> 
> Signed-off-by: Markus Elfring <elfring@...rs.sourceforge.net>
> ---
> drivers/staging/lustre/lustre/obdclass/genops.c | 3 +--
> 1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/drivers/staging/lustre/lustre/obdclass/genops.c b/drivers/staging/lustre/lustre/obdclass/genops.c
> index fd5e61f..4752091 100644
> --- a/drivers/staging/lustre/lustre/obdclass/genops.c
> +++ b/drivers/staging/lustre/lustre/obdclass/genops.c
> @@ -152,10 +152,9 @@ int class_register_type(struct obd_ops *dt_ops, struct md_ops *md_ops,
> 		return -EEXIST;
> 	}
> 
> -	rc = -ENOMEM;

NAK.
when you do this, the next statement below breaks:

> 	type = kzalloc(sizeof(*type), GFP_NOFS);
> 	if (!type)
> -		return rc;
> +		return -ENOMEM;
> 
> 	type->typ_dt_ops = kzalloc(sizeof(*type->typ_dt_ops), GFP_NOFS);
> 	if (!type->typ_dt_ops) {
…
                goto failed;

 failed:
…
return rc;

So we are now returning an unitialized rc, did you get a gcc warning about it when compiling?