From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id BB31848A2A0; Mon, 31 Aug 2026 13:38:15 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788183496; cv=none; b=mWbo/EtbO5hmfgEys0K54rLj1Jd0kw1uRVFj5IvhpksaiYPoY48RfYTeHq3jtHI5PIWKLmpnu2g+HEGllw7jMPWCrfQPRyRENWOZdCfyy/oEKBiB+HIJCgv0ysiH97rtTW/onvI2Xgdh9Jo+Y6vvI7famk/4itc4le88gP/quJI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788183496; c=relaxed/simple; bh=FOYpELJOaS1P0sDXeTx486Ydf+g+sO3kPqrnnGU27RA=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=X/tWX5Zg3bJOTeEwGLeV9zzj8W9Ox96ReOymgOEvBGnfppknHoA/1hkpH5VqVIeLAaCPdvaCcErCwnZ69mV/Zlbv2/Cnk0vaJ843CrKEtq6+eAcyNKAMRxScTPGHk/TJBwgHcJt9vURXhXAuRnqMbiYVILEhDiV0kHC1n5xXTD4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=Q98BG+fD; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="Q98BG+fD" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 20B061F00A3E; Mon, 31 Aug 2026 13:38:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1788183495; bh=8mnUQ12pErh1BT66Y/Tgm4C3BkW/vOk4dGwvdmEAzVI=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=Q98BG+fDnHGI7biqE+5OUxFbHOTZIlqQPmMgzCP0ZFSLjAMtMJjgKPNx/BM8fKXLN QIrOVGmvy8ppcr3nif2ApnaK8T8epN8/K+54RaDpxigSiMCI1TJwxP/662QvvE1y9W JEDXqfWqu+yte9OmxSPCjied5cHx2AVuWFf0eryY= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Shuangpeng Bai Subject: [PATCH 7.2 19/71] usb: gadget: f_tcm: keep port count until LUN teardown completes Date: Mon, 31 Aug 2026 15:33:44 +0200 Message-ID: <20260831133400.001676738@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260831133359.055927882@linuxfoundation.org> References: <20260831133359.055927882@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 7.2-stable review patch. If anyone has any objections, please let me know. ------------------ From: Shuangpeng Bai commit c39d0916da47d94909391876c9e5bd429ea7b1b9 upstream. tcm_usbg_drop_nexus() permits session removal once tpg_port_count reaches zero. However, usbg_port_unlink() currently decrements that count from the fabric_pre_unlink() callback, before core_dev_del_lun() waits for active se_lun references to drain. If removal of the last LUN races a nexus removal, the latter can observe a zero port count and call target_remove_session(). This frees sess_cmd_map while an in-flight struct usbg_cmd, including its work item, can still be accessed. Overlapping the last-LUN unlink with nexus removal reproduces this lifetime violation as a DEBUG_OBJECTS "free active" warning for usbg_cmd_work, followed by a target-core BUG/Oops. The generic target-core unlink path has no callback after core_dev_del_lun() completes. Add an optional fabric_post_unlink() callback and use it for the f_tcm port count. The count now remains nonzero until core_dev_del_lun() has finished draining active LUN references, preventing nexus removal from freeing the session during command completion. Fixes: c52661d60f63 ("usb-gadget: Initial merge of target module for UASP + BOT") Cc: stable@vger.kernel.org Signed-off-by: Shuangpeng Bai Link: https://patch.msgid.link/20260807060733.3186624-1-shuangpeng.kernel@gmail.com Signed-off-by: Greg Kroah-Hartman --- drivers/target/target_core_fabric_configfs.c | 8 ++++++++ drivers/usb/gadget/function/f_tcm.c | 2 +- include/target/target_core_fabric.h | 2 ++ 3 files changed, 11 insertions(+), 1 deletion(-) --- a/drivers/target/target_core_fabric_configfs.c +++ b/drivers/target/target_core_fabric_configfs.c @@ -690,6 +690,14 @@ static void target_fabric_port_unlink( } core_dev_del_lun(se_tpg, lun); + + if (tf->tf_ops->fabric_post_unlink) { + /* + * Allow fabrics to release state that must remain valid until + * core_dev_del_lun() has drained all active LUN references. + */ + tf->tf_ops->fabric_post_unlink(se_tpg, lun); + } } static void target_fabric_port_release(struct config_item *item) --- a/drivers/usb/gadget/function/f_tcm.c +++ b/drivers/usb/gadget/function/f_tcm.c @@ -2024,7 +2024,7 @@ static const struct target_core_fabric_o .fabric_enable_tpg = usbg_enable_tpg, .fabric_drop_tpg = usbg_drop_tpg, .fabric_post_link = usbg_port_link, - .fabric_pre_unlink = usbg_port_unlink, + .fabric_post_unlink = usbg_port_unlink, .fabric_init_nodeacl = usbg_init_nodeacl, .tfc_wwn_attrs = usbg_wwn_attrs, --- a/include/target/target_core_fabric.h +++ b/include/target/target_core_fabric.h @@ -95,6 +95,8 @@ struct target_core_fabric_ops { struct se_lun *); void (*fabric_pre_unlink)(struct se_portal_group *, struct se_lun *); + void (*fabric_post_unlink)(struct se_portal_group *se_tpg, + struct se_lun *lun); struct se_tpg_np *(*fabric_make_np)(struct se_portal_group *, struct config_group *, const char *); void (*fabric_drop_np)(struct se_tpg_np *);