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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-Archived-By: MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.4 X-Mimecast-MFC-PROC-ID: KlunXadVJwyShhMEf8MpFlEAlySFLMuUW5ncPqdwy1k_1792514689 X-Mimecast-Originator: redhat.com Content-Transfer-Encoding: 8bit content-type: text/plain; charset="US-ASCII"; x-default=true X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20261020_094457_185387_C2E50733 X-CRM114-Status: GOOD ( 14.16 ) X-Spam-Score: 1.2 (+) X-BeenThere: kexec@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "kexec" X-Spam-Status: No, score=-16.2 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=4.0.1 X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 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