linux-kernel - Re: [PATCH v2] staging: lustre: llite: Fix variable length array warning

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Message-ID: <1494199491.31950.52.camel@perches.com>
Date:   Sun, 07 May 2017 16:24:51 -0700
From:   Joe Perches <joe@...ches.com>
To:     Guru Das Srinagesh <gurooodas@...il.com>, oleg.drokin@...el.com,
        andreas.dilger@...el.com, jsimmons@...radead.org,
        gregkh@...uxfoundation.org
Cc:     lustre-devel@...ts.lustre.org, devel@...verdev.osuosl.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] staging: lustre: llite: Fix variable length array
 warning

On Sun, 2017-05-07 at 02:23 -0700, Guru Das Srinagesh wrote:
> Fix sparse warning "warning: Variable length array is used." by using
> kmalloc_array to allocate the required amount of memory instead and
> kfree to deallocate memory after use.
[]
> diff --git a/drivers/staging/lustre/lustre/llite/xattr.c b/drivers/staging/lustre/lustre/llite/xattr.c
[]
> @@ -86,13 +86,17 @@ ll_xattr_set_common(const struct xattr_handler *handler,
>  		    const char *name, const void *value, size_t size,
>  		    int flags)
>  {
> -	char fullname[strlen(handler->prefix) + strlen(name) + 1];
> +	int fullname_len = strlen(handler->prefix) + strlen(name) + 1;
> +	char *fullname = kmalloc_array(fullname_len, sizeof(char), GFP_KERNEL);

Are you sure about using GFP_KERNEL and that sleeping is
allowed for this function allocation?