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smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b="NNV0IcN/"; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 5D2F1606A324 for ; Fri, 30 Oct 2026 13:41:22 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=NNV0IcN/ Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9C1651F000C1; Fri, 30 Oct 2026 13:41:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793367682; bh=OnmTI2TmNztdeWp6xVf8mln9QukGvhxUcITWVh2aeg0=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=NNV0IcN/T1x4uk/6xUMmczMHDMjA10KxECC7FCade0M2t2SjGRrLc7DundGou1KTp uqskAND9/s3Vjvwdv9mxrcO2csTqh1TaELZoj6uHGxq+63vd6xlNNb0TXVrmYO/aIZ G350lBfPsDCXTmijg56uuZY1+LaoQ1IioK1UUFu0YxIj4vLugbnG9rBedZMYqLexNp FATQVAryPGVUez09RMlqDxdZu1xvTfGjHxQ8M1u3NsKrfej8mGgNHQbIz5vBSOoNKj 4eH0VuJtfp13xDZq9pzOYMCTNXBfAAwqBLHUV8Ah82zS2UyNLqT9R/t99RdY0u9q1B hjUIrCJJZf7ow== Message-ID: <43ac2e84-56fe-4a52-b445-0be8ccb0d573@kernel.org> Date: Fri, 30 Oct 2026 14:41:17 +0100 X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 6/9] w1: netlink: drop the slave after the bus is unlocked To: Greg Kroah-Hartman Cc: Josef Bacik , linux-kernel@vger.kernel.org, stable References: <20261027-llm-char-misc-w1-v1-0-d2e6bfafb6a4@linuxfoundation.org> <20261027-llm-char-misc-w1-v1-6-d2e6bfafb6a4@linuxfoundation.org> From: Krzysztof Kozlowski Content-Language: en-US Autocrypt: addr=krzk@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit On 27/10/2026 17:04, Greg Kroah-Hartman wrote: > From: Josef Bacik > > w1_process_cb() executes the commands of a netlink message with bus_mutex > held, and drops the reference to the slave which the message was > addressed to before it unlocks the mutex. If the slave has been detached > in the meantime, this is the last reference, and w1_unref_slave() tears > the slave down on the spot. That waits > > - in device_unregister(), for the sysfs callbacks of the slave which are > running, and > > - in w1_therm_remove_slave(), for the readers which have taken a > reference to the family data, > > and both kinds take bus_mutex to talk to the slave. Whoever is waiting > for the mutex at that moment is never going to finish, and neither is the > thread of the bus master. > > Unlock the bus first. The reference keeps the slave, and with it the > master, alive until then. > > Fixes: d3a8a9dbb903 ("w1: hold bus_mutex in netlink and search") > Cc: stable > Signed-off-by: Josef Bacik > Signed-off-by: Greg Kroah-Hartman Reviewed-by: Krzysztof Kozlowski Best regards, Krzysztof