linux-kernel - Re: [PATCH v2 2/6] staging: rtl8188eu: use safe iterator in rtw_free_all

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Message-ID: <20210517203205.GB3620180@roeck-us.net>
Date:   Mon, 17 May 2021 13:32:05 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     Martin Kaiser <martin@...ser.cx>
Cc:     Larry Finger <Larry.Finger@...inger.net>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Christophe JAILLET <christophe.jaillet@...adoo.fr>,
        Dan Carpenter <dan.carpenter@...cle.com>,
        linux-staging@...ts.linux.dev, kernel-janitors@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 2/6] staging: rtl8188eu: use safe iterator in
 rtw_free_all_stainfo

On Mon, May 17, 2021 at 10:18:22PM +0200, Martin Kaiser wrote:
> This is another case where we may remove list entries while we iterate over
> the list. Use list_for_each_entry_safe to avoid an endless loop.
> 
> Fixes: 23017c8842d2 ("staging: rtl8188eu: Use list iterators and helpers")
> Signed-off-by: Martin Kaiser <martin@...ser.cx>

Reviewed-by: Guenter Roeck <linux@...ck-us.net>

> ---
> v2:
>  - use list_for_each_entry_safe
> 
> Without this patch, unloading the module goes into an endless loop
> sometimes.
> 
>  drivers/staging/rtl8188eu/core/rtw_sta_mgt.c | 8 +++-----
>  1 file changed, 3 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/staging/rtl8188eu/core/rtw_sta_mgt.c b/drivers/staging/rtl8188eu/core/rtw_sta_mgt.c
> index 7941ca0397ed..5af7af5f5a5a 100644
> --- a/drivers/staging/rtl8188eu/core/rtw_sta_mgt.c
> +++ b/drivers/staging/rtl8188eu/core/rtw_sta_mgt.c
> @@ -379,9 +379,9 @@ u32 rtw_free_stainfo(struct adapter *padapter, struct sta_info *psta)
>  /*  free all stainfo which in sta_hash[all] */
>  void rtw_free_all_stainfo(struct adapter *padapter)
>  {
> -	struct list_head *plist, *phead;
> +	struct list_head *phead;
>  	s32 index;
> -	struct sta_info *psta = NULL;
> +	struct sta_info *psta, *temp;
>  	struct sta_priv *pstapriv = &padapter->stapriv;
>  	struct sta_info *pbcmc_stainfo = rtw_get_bcmc_stainfo(padapter);
>  
> @@ -392,9 +392,7 @@ void rtw_free_all_stainfo(struct adapter *padapter)
>  
>  	for (index = 0; index < NUM_STA; index++) {
>  		phead = &pstapriv->sta_hash[index];
> -		list_for_each(plist, phead) {
> -			psta = list_entry(plist, struct sta_info, hash_list);
> -
> +		list_for_each_entry_safe(psta, temp, phead, hash_list) {
>  			if (pbcmc_stainfo != psta)
>  				rtw_free_stainfo(padapter, psta);
>  		}
> -- 
> 2.20.1
>