From: nicolas saenz julienne <nsaenz@kernel.org>
To: Saravana Kannan <saravanak@google.com>,
Tudor Ambarus <tudor.ambarus@microchip.com>
Cc: mturquette@baylibre.com, sboyd@kernel.org, maxime@cerno.tech,
gregkh@linuxfoundation.org, rafael@kernel.org,
khilman@kernel.org, ulf.hansson@linaro.org, len.brown@intel.com,
pavel@ucw.cz, robh+dt@kernel.org, frowand.list@gmail.com,
maz@kernel.org, tglx@linutronix.de, geert@linux-m68k.org,
nsaenzjulienne@suse.de, linux@roeck-us.net,
guillaume.tucker@collabora.com, linux-clk@vger.kernel.org,
linux-kernel@vger.kernel.org, corbet@lwn.net,
nicolas.ferre@microchip.com, claudiu.beznea@microchip.com,
linux-doc@vger.kernel.org, linux-pm@vger.kernel.org,
devicetree@vger.kernel.org, linux-acpi@vger.kernel.org,
kernel-team@android.com, linux-rpi-kernel@lists.infradead.org,
Marek Szyprowski <m.szyprowski@samsung.com>
Subject: Re: [PATCH 1/2] clk: Do not register provider with a NULL dev->of_node
Date: Fri, 23 Apr 2021 20:21:59 +0200 [thread overview]
Message-ID: <528ab89224ba27f6164135a8ac00a828e7113805.camel@kernel.org> (raw)
In-Reply-To: <CAGETcx-81hPTW_EVexMWaxGSOknuK-zESqKdiuQvye=n3TaHkA@mail.gmail.com>
Hi Saravana, Tudor,
On Fri, 2021-04-23 at 10:24 -0700, Saravana Kannan wrote:
> On Fri, Apr 23, 2021 at 10:14 AM Tudor Ambarus
> <tudor.ambarus@microchip.com> wrote:
> >
> > commit 6579c8d97ad7 ("clk: Mark fwnodes when their clock provider is added")
> > revealed that clk/bcm/clk-raspberrypi.c driver calls
> > devm_of_clk_add_hw_provider(), with a NULL dev->of_node.
> >
> > devm_of_clk_add_hw_provider() should not register the provider with
> > a NULL dev->of_node, as there is no of_node. Apart of the NULL pointer
> > dereference that will result when calling fwnode_dev_initialized() in
> > of_clk_add_hw_provider(), another problem is that when two drivers calling
> > of_clk_add_hw_provider() with np = NULL, their unregistration order is not
> > guaranteed to be correct. Avoid all the problems and just return -ENODEV
> > when the callers of devm_of_clk_add_hw_provider() use a NULL dev->of_node,
> > which seems the natural way to do.
> >
> > Reported-by: Marek Szyprowski <m.szyprowski@samsung.com>
> > Fixes: 6579c8d97ad7 ("clk: Mark fwnodes when their clock provider is added")
> > Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com>
> > ---
> > drivers/clk/clk.c | 12 +++++++-----
> > 1 file changed, 7 insertions(+), 5 deletions(-)
> >
> > diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
> > index e2ec1b745243..8b5077cc5e67 100644
> > --- a/drivers/clk/clk.c
> > +++ b/drivers/clk/clk.c
> > @@ -4634,11 +4634,10 @@ static struct device_node *get_clk_provider_node(struct device *dev)
> > * @get: callback for decoding clk_hw
> > * @data: context pointer for @get callback
> > *
> > - * Registers clock provider for given device's node. If the device has no DT
> > - * node or if the device node lacks of clock provider information (#clock-cells)
> > - * then the parent device's node is scanned for this information. If parent node
> > - * has the #clock-cells then it is used in registration. Provider is
> > - * automatically released at device exit.
> > + * Registers clock provider for given device's node. If the device node lacks
> > + * of clock provider information (#clock-cells) then the parent device's node is
> > + * scanned for this information. If parent node has the #clock-cells then it is
> > + * used in registration. Provider is automatically released at device exit.
> > *
> > * Return: 0 on success or an errno on failure.
> > */
> > @@ -4650,6 +4649,9 @@ int devm_of_clk_add_hw_provider(struct device *dev,
> > struct device_node **ptr, *np;
> > int ret;
> >
> > + if (!dev->of_node)
> > + return -ENODEV;
> > +
>
> Based on the other discussions, for now, just return 0. The error
> might cause other issues in other drivers. We can clean this up later.
+1, Let's return 0 and do nothing skip the logic in the driver.
Now, from what I read in devm_of_clk_add_hw_provider(), there is a use case for
entering with '!dev->of_node'. See get_clk_provider_node()'s usage. So I think
we should only bail if that function fails to provide a device_node.
Regards,
Nicolas
next prev parent reply other threads:[~2021-04-23 18:22 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-23 17:13 [PATCH 0/2] clk: Do not register provider with a NULL dev->of_node Tudor Ambarus
2021-04-23 17:13 ` [PATCH 1/2] " Tudor Ambarus
2021-04-23 17:24 ` Saravana Kannan
2021-04-23 18:21 ` nicolas saenz julienne [this message]
2021-04-23 18:35 ` Tudor.Ambarus
2021-04-23 17:13 ` [PATCH 2/2] clk: bcm: rpi: Do not call devm_of_clk_add_hw_provider " Tudor Ambarus
2021-04-23 19:12 ` [PATCH] clk: Skip clk provider registration when np is NULL Tudor Ambarus
2021-04-23 19:16 ` Tudor.Ambarus
2021-04-24 1:17 ` Stephen Boyd
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