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Date: Tue, 17 Mar 2026 17:20:51 +0100
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Subject: Re: [PATCH v2] device property: Make modifications of fwnode "flags"
 thread safe
To: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Douglas Anderson <dianders@chromium.org>,
 Greg Kroah-Hartman <gregkh@linuxfoundation.org>, stable@vger.kernel.org,
 Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
 Mark Brown <broonie@kernel.org>,
 Wolfram Sang <wsa+renesas@sang-engineering.com>, Andrew Lunn
 <andrew@lunn.ch>, Daniel Scally <djrscally@gmail.com>,
 "David S. Miller" <davem@davemloft.net>, Eric Dumazet <edumazet@google.com>,
 Fabio Estevam <festevam@gmail.com>, Frank Li <Frank.Li@nxp.com>,
 Heikki Krogerus <heikki.krogerus@linux.intel.com>,
 Heiner Kallweit <hkallweit1@gmail.com>, Jakub Kicinski <kuba@kernel.org>,
 Len Brown <lenb@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
 Pengutronix Kernel Team <kernel@pengutronix.de>,
 Rob Herring <robh@kernel.org>, Russell King <linux@armlinux.org.uk>,
 Sakari Ailus <sakari.ailus@linux.intel.com>,
 Saravana Kannan <saravanak@kernel.org>, Sascha Hauer
 <s.hauer@pengutronix.de>, devicetree@vger.kernel.org,
 driver-core@lists.linux.dev, imx@lists.linux.dev,
 linux-acpi@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
 linux-i2c@vger.kernel.org, linux-kernel@vger.kernel.org,
 linux-spi@vger.kernel.org, netdev@vger.kernel.org
References: <20260317090112.v2.1.I0a4d03104ecd5103df3d76f66c8d21b1d15a2e38@changeid>
 <CAJZ5v0hwO16=mP_vB=wi7x8CjROAw_Nd_Tq-hEohrDW3C58RbA@mail.gmail.com>
From: Danilo Krummrich <dakr@kernel.org>
Content-Language: en-US
In-Reply-To: <CAJZ5v0hwO16=mP_vB=wi7x8CjROAw_Nd_Tq-hEohrDW3C58RbA@mail.gmail.com>
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On 3/17/2026 5:11 PM, Rafael J. Wysocki wrote:
> On Tue, Mar 17, 2026 at 5:04 PM Douglas Anderson <dianders@chromium.org> wrote:
>>
>> In various places in the kernel, we modify the fwnode "flags" member
>> by doing either:
>>   fwnode->flags |= SOME_FLAG;
>>   fwnode->flags &= ~SOME_FLAG;
>>
>> This type of modification is not thread-safe. If two threads are both
>> mucking with the flags at the same time then one can clobber the
>> other.
>>
>> While flags are often modified while under the "fwnode_link_lock",
>> this is not universally true.
>>
>> Create some accessor functions for setting, clearing, and testing the
>> FWNODE flags and move all users to these accessor functions. New
>> accessor functions use set_bit() and clear_bit(), which are
>> thread-safe.
>>
>> Cc: stable@vger.kernel.org
>> Fixes: c2c724c868c4 ("driver core: Add fw_devlink_parse_fwtree()")
>> Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
>> Acked-by: Mark Brown <broonie@kernel.org>
>> Reviewed-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
>> Signed-off-by: Douglas Anderson <dianders@chromium.org>
> 
> Rafael J. Wysocki (Intel) <rafael@kernel.org>

ACK or RB?