Subject: Re: [PATCH 03/10] batman-adv: Make DAT capability changes atomic

From: Sergei Shtylyov <sergei.shtylyov-M4DtvfQ/[email-masked]>
Date: Tue, 11 Aug 2015 22:36:50 +0300

Hello.

On 08/11/2015 07:35 PM, Antonio Quartulli wrote:

> From: Linus Lüssing <[email-masked]>

> Bitwise OR/AND assignments in C aren't guaranteed to be atomic. One
> OGM handler might undo the set/clear of a specific bit from another
> handler run in between.

> Fix this by using the atomic set_bit()/clear_bit()/test_bit() functions.

> Fixes: 17cf0ea455f1 ("batman-adv: tvlv - add distributed arp table container")
> Signed-off-by: Linus Lüssing <[email-masked]>
> Signed-off-by: Marek Lindner <[email-masked]>
> Signed-off-by: Antonio Quartulli <[email-masked]>
> ---
>   net/batman-adv/distributed-arp-table.c | 7 ++++---
>   net/batman-adv/types.h                 | 4 ++--
>   2 files changed, 6 insertions(+), 5 deletions(-)

> diff --git a/net/batman-adv/distributed-arp-table.c b/net/batman-adv/distributed-arp-table.c
> index fb54e6a..244dcf6 100644
> --- a/net/batman-adv/distributed-arp-table.c
> +++ b/net/batman-adv/distributed-arp-table.c
[...]
> @@ -453,7 +454,7 @@ static bool batadv_is_orig_node_eligible(struct batadv_dat_candidate *res,
>   	int j;
>
>   	/* check if orig node candidate is running DAT */
> -	if (!(candidate->capabilities & BATADV_ORIG_CAPA_HAS_DAT))
> +	if (!(test_bit(BATADV_ORIG_CAPA_HAS_DAT, &candidate->capabilities)))

    () around the tst_bit() call not needed.

[...]

MBR, Sergei