From: Thierry Reding <thierry.reding@gmail.com>
To: Jeffy Chen <jeffy.chen@rock-chips.com>
Cc: linux-kernel@vger.kernel.org, dmitry.torokhov@gmail.com,
heiko@sntech.de, briannorris@chromium.org, rjw@rjwysocki.net,
dianders@chromium.org, tfiga@chromium.org, broonie@kernel.org,
seanpaul@chromium.org, linux-pwm@vger.kernel.org
Subject: Re: [RFC PATCH v4 7/8] pwm: Add dummy pwmchip for orphan pwms
Date: Tue, 17 Oct 2017 14:40:31 +0200 [thread overview]
Message-ID: <20171017124031.GA27983@ulmo> (raw)
In-Reply-To: <20171017101624.12506-8-jeffy.chen@rock-chips.com>
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On Tue, Oct 17, 2017 at 06:16:23PM +0800, Jeffy Chen wrote:
> When the pwm driver is unbound while the pwm is still requested, the
> pwm core would not actually remove the pwmchip(return -EBUSY instead).
>
> So it would hold some references to the invalid resources(e.g. pwmchip).
>
> And the customer who requested the pwm would have those references too,
> and may crash the kernel when trying to access them later.
>
> Add a dummy pwmchip, and assign orphan pwms to it to avoid that.
>
> Signed-off-by: Jeffy Chen <jeffy.chen@rock-chips.com>
> ---
>
> Changes in v4:
> Fix compile warning.
>
> Changes in v3:
> Assign orphan pwms to dummy pwmchip instead of adding device link in the
> customer driver.
What happened to this? Device links were specifically designed to avoid
situations like these.
A dummy PWM chip doesn't seem like the right solution to this.
Thierry
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next prev parent reply other threads:[~2017-10-17 12:40 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-10-17 10:16 [RFC PATCH v4 0/8] rockchip: kevin: Enable edp display Jeffy Chen
2017-10-17 10:16 ` [RFC PATCH v4 1/8] arm64: dts: rockchip: Enable edp disaplay on kevin Jeffy Chen
2017-10-17 10:16 ` [RFC PATCH v4 2/8] drm/rockchip: analogix_dp: Fix error handling path Jeffy Chen
2017-10-17 17:57 ` Sean Paul
2017-10-17 10:16 ` [RFC PATCH v4 3/8] drm/rockchip: dw-mipi-dsi: " Jeffy Chen
2017-10-17 18:02 ` Sean Paul
2017-10-17 10:16 ` [RFC PATCH v4 4/8] drm/rockchip: dw_hdmi: " Jeffy Chen
2017-10-17 18:10 ` Sean Paul
2017-10-19 1:54 ` jeffy
2017-10-17 10:16 ` [RFC PATCH v4 5/8] drm/rockchip: inno_hdmi: " Jeffy Chen
2017-10-17 18:18 ` Sean Paul
2017-10-17 10:16 ` [RFC PATCH v4 6/8] drm/bridge/analogix: Do not use device's drvdata Jeffy Chen
2017-10-17 18:18 ` Sean Paul
2017-10-17 23:43 ` Jingoo Han
2017-10-18 4:46 ` Archit Taneja
2017-10-17 10:16 ` [RFC PATCH v4 7/8] pwm: Add dummy pwmchip for orphan pwms Jeffy Chen
2017-10-17 12:40 ` Thierry Reding [this message]
2017-10-17 17:04 ` Brian Norris
2017-10-17 18:24 ` Dmitry Torokhov
2017-10-17 18:46 ` Mark Brown
2017-10-17 18:53 ` Brian Norris
2017-10-17 19:05 ` Mark Brown
2017-10-18 5:16 ` jeffy
2017-10-17 10:16 ` [RFC PATCH v4 8/8] drm/rockchip: Add device links for master and components Jeffy Chen
2017-10-17 18:24 ` Sean Paul
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