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Wysocki" , Danilo Krummrich Cc: linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org, linux-scsi@vger.kernel.org, Tarun Sahu , Stuart Hayes , Laurence Oberman , Bjorn Helgaas , kexec@lists.infradead.org, "Ewan Milne" , "John Meneghini" , "Lombardi, Maurizio" , "Bart Van Assche" , "John Garry" , "Jeremy Allison" , "Martin K . Petersen" , "Pasha Tatashin" , David Jeffery Subject: [PATCH 1/9] driver core: rely on put_device to free dev->p Date: Tue, 20 Oct 2026 12:44:27 -0400 Message-ID: <20261020164435.80499-2-djeffery@redhat.com> In-Reply-To: <20261020164435.80499-1-djeffery@redhat.com> References: <20261020164435.80499-1-djeffery@redhat.com> X-Mailing-List: driver-core@lists.linux.dev List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.4 X-Mimecast-MFC-PROC-ID: 3q_6WVdu7_GptmcfWcFOWUY6veQgClAyX6gggWyl4Ic_1792514689 X-Mimecast-Originator: redhat.com Content-Transfer-Encoding: 8bit content-type: text/plain; charset="US-ASCII"; x-default=true From: Tarun Sahu device_add allocate private_data for device and assigns to dev->p. If device_add fails in later steps of the function, it cleans up this dev->p which is not necessary because In the next call, put_device free it anyway (if reference to the device is 0 which will be unless someone concurrently get the reference to this device). This avoids unnecessary races introduced in system. After device is added in device_kset->list by device_add and later steps in the device_add function failures occur, it will free dev->p manually, while in between there might be a user of device_kset->list will take reference to the device just added by device_add. and might try to access dev->p. So relying on put_device to free dev->p prevents such problem. Signed-off-by: Tarun Sahu Signed-off-by: David Jeffery Tested-by: Laurence Oberman --- drivers/base/core.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/drivers/base/core.c b/drivers/base/core.c index 4c0c373998a1..83263e3fa5d4 100644 --- a/drivers/base/core.c +++ b/drivers/base/core.c @@ -2618,6 +2618,7 @@ static void device_release(struct kobject *kobj) struct device *dev = kobj_to_dev(kobj); struct device_private *p = dev->p; + dev->p = NULL; /* * Some platform devices are driven without driver attached * and managed resources may have been acquired. Make sure @@ -3828,8 +3829,6 @@ int device_add(struct device *dev) parent_error: put_device(parent); name_error: - kfree(dev->p); - dev->p = NULL; goto done; } EXPORT_SYMBOL_GPL(device_add); -- 2.55.0