linux-kernel - Re: [PATCH v2 2/2] staging: r8188eu: Use kzalloc() with GFP

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Message-ID: <YgvQZDBLCsvwTtJM@kroah.com>
Date:   Tue, 15 Feb 2022 17:10:12 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     "Fabio M. De Francesco" <fmdefrancesco@...il.com>
Cc:     Larry Finger <Larry.Finger@...inger.net>,
        Phillip Potter <phil@...lpotter.co.uk>,
        linux-staging@...ts.linux.dev, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 2/2] staging: r8188eu: Use kzalloc() with GFP_ATOMIC
 in atomic context

On Tue, Feb 08, 2022 at 07:04:26PM +0100, Fabio M. De Francesco wrote:
> Use the GFP_ATOMIC flag of kzalloc() with two memory allocation in rtw_set_key() 
> because it is not allowed to sleep while it executes in atomic context.
> 
> With the GFP_ATOMIC type flag, the allocation is high priority and thus it 
> cannot sleep.
> 
> This issue is detected by Smatch which emits the following warning:
> 
> "drivers/staging/r8188eu/core/rtw_mlme.c:1603 rtw_set_key() warn: sleeping in atomic context".
> 
> Fixes: 79f712ea994d ("staging: r8188eu: Remove wrappers for kalloc() and kzalloc()")
> Fixes: 15865124feed ("staging: r8188eu: introduce new core dir for RTL8188eu driver")
> Signed-off-by: Fabio M. De Francesco <fmdefrancesco@...il.com>
> ---
>  drivers/staging/r8188eu/core/rtw_mlme.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/staging/r8188eu/core/rtw_mlme.c b/drivers/staging/r8188eu/core/rtw_mlme.c
> index f5b2df72e0f4..860835e29b79 100644
> --- a/drivers/staging/r8188eu/core/rtw_mlme.c
> +++ b/drivers/staging/r8188eu/core/rtw_mlme.c
> @@ -1600,12 +1600,12 @@ int rtw_set_key(struct adapter *adapter, struct security_priv *psecuritypriv, in
>  	struct mlme_priv		*pmlmepriv = &adapter->mlmepriv;
>  	int	res = _SUCCESS;
>  
> -	pcmd = kzalloc(sizeof(*pcmd), GFP_KERNEL);
> +	pcmd = kzalloc(sizeof(*pcmd), GFP_ATOMIC);
>  	if (!pcmd) {
>  		res = _FAIL;  /* try again */
>  		goto exit;
>  	}
> -	psetkeyparm = kzalloc(sizeof(*psetkeyparm), GFP_KERNEL);
> +	psetkeyparm = kzalloc(sizeof(*psetkeyparm), GFP_ATOMIC);
>  	if (!psetkeyparm) {
>  		kfree(pcmd);
>  		res = _FAIL;
> -- 
> 2.34.1

What code path is calling this in atomic context?

thanks,

greg k-h