Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::3:7 as permitted sender) client-ip=2620:137:e000::3:7;
Date:   Wed, 6 Dec 2023 09:39:17 -0800
From:   Stephen Hemminger <stephen@networkplumber.org>
To:     Judy Hsiao <judyhsiao@chromium.org>
Cc:     Eric Dumazet <edumazet@google.com>,
        David Ahern <dsahern@kernel.org>,
        Simon Horman <horms@kernel.org>,
        Douglas Anderson <dianders@chromium.org>,
        Brian Haley <haleyb.dev@gmail.com>,
        "David S. Miller" <davem@davemloft.net>,
        Jakub Kicinski <kuba@kernel.org>,
        Joel Granados <joel.granados@gmail.com>,
        Julian Anastasov <ja@ssi.bg>,
        Leon Romanovsky <leon@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>, linux-kernel@vger.kernel.org,
        netdev@vger.kernel.org
Subject: Re: [PATCH v2] neighbour: Don't let neigh_forced_gc() disable
 preemption for long
Message-ID: <20231206093917.04fd57b5@hermes.local>
In-Reply-To: <20231206033913.1290566-1-judyhsiao@chromium.org>
References: <20231206033913.1290566-1-judyhsiao@chromium.org>
MIME-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
Content-Transfer-Encoding: 7bit
Precedence: bulk

On Wed,  6 Dec 2023 03:38:33 +0000
Judy Hsiao <judyhsiao@chromium.org> wrote:

> diff --git a/net/core/neighbour.c b/net/core/neighbour.c
> index df81c1f0a570..552719c3bbc3 100644
> --- a/net/core/neighbour.c
> +++ b/net/core/neighbour.c
> @@ -253,9 +253,11 @@ static int neigh_forced_gc(struct neigh_table *tbl)
>  {
>  	int max_clean = atomic_read(&tbl->gc_entries) -
>  			READ_ONCE(tbl->gc_thresh2);
> +	u64 tmax = ktime_get_ns() + NSEC_PER_MSEC;
>  	unsigned long tref = jiffies - 5 * HZ;
>  	struct neighbour *n, *tmp;
>  	int shrunk = 0;
> +	int loop = 0;
>  
>  	NEIGH_CACHE_STAT_INC(tbl, forced_gc_runs);
>  
> @@ -278,11 +280,16 @@ static int neigh_forced_gc(struct neigh_table *tbl)
>  				shrunk++;
>  			if (shrunk >= max_clean)
>  				break;
> +			if (++loop == 16) {

Overall looks good.
Minor comments:
	- loop count should probably be unsigned
        - the magic constant 16 should be a sysctl tuneable