linux-kernel - Re: [PATCH v9 3/7] srcu: Fix invoke_rcu

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Message-ID: <20201103144714.GA432431@lothringen>
Date:   Tue, 3 Nov 2020 15:47:14 +0100
From:   Frederic Weisbecker <frederic@...nel.org>
To:     "Joel Fernandes (Google)" <joel@...lfernandes.org>
Cc:     linux-kernel@...r.kernel.org,
        Josh Triplett <josh@...htriplett.org>,
        Lai Jiangshan <jiangshanlai@...il.com>,
        Marco Elver <elver@...gle.com>,
        Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
        "Paul E. McKenney" <paulmck@...nel.org>, rcu@...r.kernel.org,
        Steven Rostedt <rostedt@...dmis.org>,
        "Uladzislau Rezki (Sony)" <urezki@...il.com>, fweisbec@...il.com,
        neeraj.iitr10@...il.com
Subject: Re: [PATCH v9 3/7] srcu: Fix invoke_rcu_callbacks() segcb length
 adjustment

On Tue, Nov 03, 2020 at 09:25:59AM -0500, Joel Fernandes (Google) wrote:
> With earlier patches, the negative counting of the unsegmented list
> cannot be used to adjust the segmented one. To fix this, sample the
> unsegmented length in advance, and use it after CB execution to adjust
> the segmented list's length.
> 
> Reviewed-by: Frederic Weisbecker <frederic@...nel.org>
> Suggested-by: Frederic Weisbecker <frederic@...nel.org>
> Signed-off-by: Joel Fernandes (Google) <joel@...lfernandes.org>

This breaks bisection, you need to either fix up the previous patch
by adding this diff inside or better yet: expand what you did
in "rcu/tree: Make rcu_do_batch count how many callbacks were executed"
to also handle srcu before introducing the segcb count.

Thanks.