linux-kernel - Re: [PATCH v3 6/8] pwm: rzg2l-gpt: Add suspend/resume support

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Message-ID: <ydqyvme43ul6ui7bl37kv3kuhn7js7tvkje2u4a3vasiw4kgdv@w2govkhaa3xz>
Date: Mon, 1 Dec 2025 16:28:58 +0100
From: Uwe Kleine-König <ukleinek@...nel.org>
To: Biju Das <biju.das.jz@...renesas.com>
Cc: "biju.das.au" <biju.das.au@...il.com>, 
	Philipp Zabel <p.zabel@...gutronix.de>, "linux-pwm@...r.kernel.org" <linux-pwm@...r.kernel.org>, 
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, Geert Uytterhoeven <geert+renesas@...der.be>, 
	Prabhakar Mahadev Lad <prabhakar.mahadev-lad.rj@...renesas.com>, 
	"linux-renesas-soc@...r.kernel.org" <linux-renesas-soc@...r.kernel.org>, "linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>
Subject: Re: [PATCH v3 6/8] pwm: rzg2l-gpt: Add suspend/resume support

Hello Biju,

On Mon, Dec 01, 2025 at 03:04:08PM +0000, Biju Das wrote:
> You mean to avoid unbalance between suspend()/resume(), we should not
> do error handling in resume()??

Consider the following resume function:

	static int myresume(...)
	{
		ret = enable_some_resource(...);
		if (ret)
			return ret;

		ret = enable_some_other_resource(...)
		if (ret) {
			disable_some_resource();
			return ret;

		}

		return 0;
	}

If disable_some_resource() can fail it might happen that the first call
to myresume() is left with some_resource enabled and some_other_resource
disabled (i.e. if both enable_some_other_resource() and
disable_some_resource() fail). Now if the resume is retried
some_resource is enabled a second time without being tracked and a later
suspend (or remove) won't bring the enable count to 0 and thus leak a
resource.

Best regards
Uwe

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