From: Florian Westphal <fw@strlen.de>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Florian Westphal <fw@strlen.de>,
Anatol Pomozov <anatol.pomozov@gmail.com>,
Dmitry Vyukov <dvyukov@google.com>,
paulmck@linux.ibm.com, LKML <linux-kernel@vger.kernel.org>
Subject: Re: seqcount usage in xt_replace_table()
Date: Thu, 10 Jan 2019 23:29:20 +0100 [thread overview]
Message-ID: <20190110222920.jqpzzv74huc2lb7f@breakpoint.cc> (raw)
In-Reply-To: <20190110202533.GK2861@worktop.programming.kicks-ass.net>
Peter Zijlstra <peterz@infradead.org> wrote:
> Would using synchronize_rcu() not also mean you can get rid of that
> xt_write_recseq*() stuff entirely?
No, because those are used to synchronize with cpus that read
the ruleset counters, see
net/ipv4/netfilter/ip_tables.c:get_counters().
> Anyway, synchronize_rcu() can also take a little while, but I don't
> think anywere near 30 seconds.
Ok, I think in that case it would be best to just replace the
recseq value sampling with smp_mb + synchronize_rcu plus a comment
that explains why its done.
next prev parent reply other threads:[~2019-01-10 22:29 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-01-08 19:33 Anatol Pomozov
2019-01-08 22:37 ` Florian Westphal
2019-01-10 12:41 ` Peter Zijlstra
2019-01-10 12:53 ` Dmitry Vyukov
2019-01-10 20:18 ` Peter Zijlstra
2019-01-10 14:48 ` Florian Westphal
2019-01-10 20:20 ` Peter Zijlstra
2019-01-10 20:25 ` Peter Zijlstra
2019-01-10 22:29 ` Florian Westphal [this message]
2019-01-11 8:34 ` Peter Zijlstra
2019-01-11 14:08 ` Paul E. McKenney
2019-01-10 14:52 ` Paul E. McKenney
2019-01-09 0:02 ` Andrea Parri
2019-01-09 0:36 ` Anatol Pomozov
2019-01-09 5:35 ` Dmitry Vyukov
2019-01-09 11:24 ` Andrea Parri
2019-01-09 11:55 ` Dmitry Vyukov
2019-01-09 12:11 ` Andrea Parri
2019-01-09 12:29 ` Dmitry Vyukov
2019-01-09 17:10 ` Paul E. McKenney
2019-01-10 8:49 ` Dmitry Vyukov
2019-01-10 12:30 ` Andrea Parri
2019-01-10 12:38 ` Dmitry Vyukov
2019-01-10 12:46 ` Andrea Parri
2019-01-10 13:25 ` Dmitry Vyukov
2019-01-10 14:50 ` Paul E. McKenney
2019-01-10 12:44 ` Peter Zijlstra
2019-01-10 12:54 ` Dmitry Vyukov
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