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From: Philipp Zabel <p.zabel@pengutronix.de>
To: WenTao Liang <vulab@iscas.ac.cn>
Cc: alexandre.belloni@bootlin.com, neil.armstrong@linaro.org,
	khilman@baylibre.com, jbrunet@baylibre.com,
	martin.blumenstingl@googlemail.com, ben.dooks@codethink.co.uk,
	linux-rtc@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
	linux-amlogic@lists.infradead.org, linux-kernel@vger.kernel.org,
	stable@vger.kernel.org
Subject: Re: [PATCH] rtc: meson: fix refcount leak in meson_rtc_get_bus
Date: Thu, 11 Jun 2026 10:08:55 +0200	[thread overview]
Message-ID: <aiptFzFoLzQNMlxS@pengutronix.de> (raw)
In-Reply-To: <20260611035605.59906-1-vulab@iscas.ac.cn>

On Thu, Jun 11, 2026 at 11:56:05AM +0800, WenTao Liang wrote:
> In meson_rtc_get_bus(), reset_control_reset() is called to trigger
> a hardware reset when the serial bus is not ready. The function may
> retry up to three times, but neither the successful nor the failure
> path calls reset_control_rearm() to balance the reference count,
> leaking the triggered_count on shared reset controls.

Wrong, this driver uses exclusive reset control, which does not do any
refcounting. Arguably, it should request the reset control via
devm_regulator_get_exclusive() instead of devm_regulator_get() to
make this clear.

> Fix this by adding reset_control_rearm() after reset_control_reset()
> on both the error return path and the success path within the retry
> loop, ensuring the reset control can be re-triggered on subsequent
> bus acquisition attempts.

This doesn't fix anything, reset_control_rearm() does nothing and
should not be used with exclusive reset controls.

regards
Philipp

_______________________________________________
linux-amlogic mailing list
linux-amlogic@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-amlogic

WARNING: multiple messages have this Message-ID (diff)
From: Philipp Zabel <p.zabel@pengutronix.de>
To: WenTao Liang <vulab@iscas.ac.cn>
Cc: alexandre.belloni@bootlin.com, neil.armstrong@linaro.org,
	khilman@baylibre.com, jbrunet@baylibre.com,
	martin.blumenstingl@googlemail.com, ben.dooks@codethink.co.uk,
	linux-rtc@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
	linux-amlogic@lists.infradead.org, linux-kernel@vger.kernel.org,
	stable@vger.kernel.org
Subject: Re: [PATCH] rtc: meson: fix refcount leak in meson_rtc_get_bus
Date: Thu, 11 Jun 2026 10:08:55 +0200	[thread overview]
Message-ID: <aiptFzFoLzQNMlxS@pengutronix.de> (raw)
In-Reply-To: <20260611035605.59906-1-vulab@iscas.ac.cn>

On Thu, Jun 11, 2026 at 11:56:05AM +0800, WenTao Liang wrote:
> In meson_rtc_get_bus(), reset_control_reset() is called to trigger
> a hardware reset when the serial bus is not ready. The function may
> retry up to three times, but neither the successful nor the failure
> path calls reset_control_rearm() to balance the reference count,
> leaking the triggered_count on shared reset controls.

Wrong, this driver uses exclusive reset control, which does not do any
refcounting. Arguably, it should request the reset control via
devm_regulator_get_exclusive() instead of devm_regulator_get() to
make this clear.

> Fix this by adding reset_control_rearm() after reset_control_reset()
> on both the error return path and the success path within the retry
> loop, ensuring the reset control can be re-triggered on subsequent
> bus acquisition attempts.

This doesn't fix anything, reset_control_rearm() does nothing and
should not be used with exclusive reset controls.

regards
Philipp


  parent reply	other threads:[~2026-06-11  8:09 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-06-11  3:56 [PATCH] rtc: meson: fix refcount leak in meson_rtc_get_bus WenTao Liang
2026-06-11  3:56 ` WenTao Liang
2026-06-11  4:03 ` sashiko-bot
2026-06-11  8:08 ` Philipp Zabel [this message]
2026-06-11  8:08   ` Philipp Zabel
  -- strict thread matches above, loose matches on Subject: below --
2026-06-11  3:40 WenTao Liang
2026-06-11  3:40 ` WenTao Liang
2026-06-11  3:47 ` sashiko-bot

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