linux-kernel - Re: [PATCH] staging: lustre: lnet: avoid uninitialized return value

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Date:   Wed, 17 Jan 2018 16:05:45 +0000 (GMT)
From:   James Simmons <jsimmons@...radead.org>
To:     Arnd Bergmann <arnd@...db.de>
cc:     Oleg Drokin <oleg.drokin@...el.com>,
        Andreas Dilger <andreas.dilger@...el.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        NeilBrown <neilb@...e.com>, Tejun Heo <tj@...nel.org>,
        lustre-devel@...ts.lustre.org, devel@...verdev.osuosl.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] staging: lustre: lnet: avoid uninitialized return
 value


> gcc warns that the latest workqueue change leads to returning an
> uninitialized variable:
> 
> drivers/staging/lustre/lnet/selftest/module.c: In function 'lnet_selftest_init':
> drivers/staging/lustre/lnet/selftest/module.c:98:10: error: 'rc' may be used uninitialized in this function [-Werror=maybe-uninitialized]
> 
> A failure from alloc_ordered_workqueue() tends to indicate an
> out-of-memory condition, so return -ENOMEM in both cases.
> The second error path was a preexisting bug, where we always
> returned zero after a kvmalloc_array() failure.

Reviewed-by: James Simmons <jsimmons@...radead.org>
 
> Fixes: 6106c0f82481 ("staging: lustre: lnet: convert selftest to use workqueues")
> Signed-off-by: Arnd Bergmann <arnd@...db.de>
> ---
>  drivers/staging/lustre/lnet/selftest/module.c | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/staging/lustre/lnet/selftest/module.c b/drivers/staging/lustre/lnet/selftest/module.c
> index aa6bfd5baf2f..c8d999e64f28 100644
> --- a/drivers/staging/lustre/lnet/selftest/module.c
> +++ b/drivers/staging/lustre/lnet/selftest/module.c
> @@ -95,15 +95,17 @@ lnet_selftest_init(void)
>  	lst_serial_wq = alloc_ordered_workqueue("lst_s", 0);
>  	if (!lst_serial_wq) {
>  		CERROR("Failed to create serial WI scheduler for LST\n");
> -		return rc;
> +		return -ENOMEM;
>  	}
>  	lst_init_step = LST_INIT_WI_SERIAL;
>  
>  	nscheds = cfs_cpt_number(lnet_cpt_table());
>  	lst_test_wq = kvmalloc_array(nscheds, sizeof(lst_test_wq[0]),
>  					GFP_KERNEL | __GFP_ZERO);
> -	if (!lst_test_wq)
> +	if (!lst_test_wq) {
> +		rc = -ENOMEM;
>  		goto error;
> +	}
>  
>  	lst_init_step = LST_INIT_WI_TEST;
>  	for (i = 0; i < nscheds; i++) {
> @@ -116,6 +118,7 @@ lnet_selftest_init(void)
>  		if (!lst_test_wq[i]) {
>  			CWARN("Failed to create CPU partition affinity WI scheduler %d for LST\n",
>  			      i);
> +			rc = -ENOMEM;
>  			goto error;
>  		}
>  		attrs.nice = 0;
> -- 
> 2.9.0
> 
>