From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ingo Molnar Subject: Re: [PATCH 2/2] ipvs: Use cond_resched_rcu_lock() helper when dumping connections Date: Fri, 26 Apr 2013 08:15:34 +0200 Message-ID: <20130426061534.GB25912@gmail.com> References: <1366940708-10180-1-git-send-email-horms@verge.net.au> <1366940708-10180-3-git-send-email-horms@verge.net.au> Mime-Version: 1.0 Return-path: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=x-received:sender:date:from:to:cc:subject:message-id:references :mime-version:content-type:content-disposition:in-reply-to :user-agent; bh=Ecq5gNtJfufYEzdR2ooj9AAiCraLn/sf4mO0VopDEzQ=; b=jW4yA/f2K+zQXNXflf7wlNSOvObM5z96p+SxiPP5/m9YpXXRjzQgewWF2XdRcCKQE3 pJOTxchxJvN/fJ4kvZfg71ubX0Ep+RSVzVH7Ua2jNRuEAzSFoQgkcB3BAUdxEn0z+AsK BMY4gwVSZC/5ark/+B8/o+SYdVq4DvxI6IQZVEvSHYNz/POVGjUGAAdKg6RNOZbSvLeL xctfYTvBdcBSzq+1JwAETRNsTydSR4Qq1TXpns3x6nOAy8Yq1/TrLBQV9pU4gm+7/yGe k5UJJSYKdLkkBzF460MwpRt4t78eD0UU7XKXftVygZvbB5Lz+wtWvCizMZV7/wXPpGuF rk7Q== Content-Disposition: inline In-Reply-To: <1366940708-10180-3-git-send-email-horms@verge.net.au> Sender: lvs-devel-owner@vger.kernel.org List-ID: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Simon Horman Cc: Eric Dumazet , Julian Anastasov , Ingo Molnar , Peter Zijlstra , lvs-devel@vger.kernel.org, netdev@vger.kernel.org, netfilter-devel@vger.kernel.org, linux-kernel@vger.kernel.org, Pablo Neira Ayuso , Dipankar Sarma , "Paul E. McKenney" * Simon Horman wrote: > This avoids the situation where a dump of a large number of connections > may prevent scheduling for a long time while also avoiding excessive > calls to rcu_read_unlock() and rcu_read_lock(). > > Cc: Eric Dumazet > Cc: Julian Anastasov > Signed-off-by: Simon Horman > --- > net/netfilter/ipvs/ip_vs_conn.c | 6 ++---- > 1 file changed, 2 insertions(+), 4 deletions(-) > > diff --git a/net/netfilter/ipvs/ip_vs_conn.c b/net/netfilter/ipvs/ip_vs_conn.c > index a083bda..42a7b33 100644 > --- a/net/netfilter/ipvs/ip_vs_conn.c > +++ b/net/netfilter/ipvs/ip_vs_conn.c > @@ -975,8 +975,7 @@ static void *ip_vs_conn_array(struct seq_file *seq, loff_t pos) > return cp; > } > } > - rcu_read_unlock(); > - rcu_read_lock(); > + cond_resched_rcu_lock(); > } > > return NULL; > @@ -1015,8 +1014,7 @@ static void *ip_vs_conn_seq_next(struct seq_file *seq, void *v, loff_t *pos) > iter->l = &ip_vs_conn_tab[idx]; > return cp; > } > - rcu_read_unlock(); > - rcu_read_lock(); > + cond_resched_rcu_lock(); Feel free to route this via the networking tree. Note that this change isn't a pure clean-up but has functional effects as well: on !PREEMPT or PREEMPT_VOLUNTARY kernels it will add in a potential cond_resched() - while previously it would only rcu unlock and relock (which in itself isn't scheduling). This should probably be pointed out in the changelog. Thanks, Ingo