Received-SPF: pass (google.com: domain of linux-kernel+bounces-155797-linux.lists.archive=gmail.com@vger.kernel.org designates 139.178.88.99 as permitted sender) client-ip=139.178.88.99;
Message-ID: <cc21ff5ddd8fbe07e75fdffd596c0aa1.sboyd@kernel.org>
Content-Type: text/plain; charset="utf-8"
Precedence: bulk
MIME-Version: 1.0
Content-Transfer-Encoding: quoted-printable
In-Reply-To: <20240423110304.1659456-6-sashal@kernel.org>
References: <20240423110304.1659456-1-sashal@kernel.org> <20240423110304.1659456-6-sashal@kernel.org>
Subject: Re: [PATCH AUTOSEL 5.4 6/8] clk: Don't hold prepare_lock when calling kref_put()
From: Stephen Boyd <sboyd@kernel.org>
Cc: Douglas Anderson <dianders@chromium.org>, Sasha Levin <sashal@kernel.org>, mturquette@baylibre.com, linux-clk@vger.kernel.org
To: Sasha Levin <sashal@kernel.org>, linux-kernel@vger.kernel.org, stable@vger.kernel.org
Date: Tue, 23 Apr 2024 12:24:51 -0700
User-Agent: alot/0.10

Quoting Sasha Levin (2024-04-23 04:03:01)
> From: Stephen Boyd <sboyd@kernel.org>
>=20
> [ Upstream commit 6f63af7511e7058f3fa4ad5b8102210741c9f947 ]
>=20
> We don't need to hold the prepare_lock when dropping a ref on a struct
> clk_core. The release function is only freeing memory and any code with
> a pointer reference has already unlinked anything pointing to the
> clk_core. This reduces the holding area of the prepare_lock a bit.
>=20
> Note that we also don't call free_clk() with the prepare_lock held.
> There isn't any reason to do that.

You'll want the patch before this, 8358a76cfb47 ("clk: Remove
prepare_lock hold assertion in __clk_release()"), to avoid lockdep
warnings. And it looks like the problem was reported on v5.15.y so all
5 patches from the series would need a backport.

 8358a76cfb47 clk: Remove prepare_lock hold assertion in __clk_release()
 6f63af7511e7 clk: Don't hold prepare_lock when calling kref_put()
 9d05ae531c2c clk: Initialize struct clk_core kref earlier
 e581cf5d2162 clk: Get runtime PM before walking tree during disable_unused
 9d1e795f754d clk: Get runtime PM before walking tree for clk_summary