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| author | Shuangpeng Bai <shuangpeng.kernel@gmail.com> | 2026-08-07 02:07:33 -0400 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2026-09-02 14:28:35 +0200 |
| commit | 178f59a0bccd3f66cdfa5184310f31a58b7257c4 (patch) | |
| tree | d83ec4c44156fececda6ecf375e12d6fd9a63e36 | |
| parent | 40102612180f86d3d4e0bcfcb3a9825b6f2cf53b (diff) | |
| download | linux-stable-178f59a0bccd3f66cdfa5184310f31a58b7257c4.tar.gz linux-stable-178f59a0bccd3f66cdfa5184310f31a58b7257c4.zip | |
usb: gadget: f_tcm: keep port count until LUN teardown completes
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 <shuangpeng.kernel@gmail.com>
Link: https://patch.msgid.link/20260807060733.3186624-1-shuangpeng.kernel@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | drivers/target/target_core_fabric_configfs.c | 8 | ||||
| -rw-r--r-- | drivers/usb/gadget/function/f_tcm.c | 2 | ||||
| -rw-r--r-- | include/target/target_core_fabric.h | 2 |
3 files changed, 11 insertions, 1 deletions
diff --git a/drivers/target/target_core_fabric_configfs.c b/drivers/target/target_core_fabric_configfs.c index 95a88f6224cd..f01ef73552fb 100644 --- a/drivers/target/target_core_fabric_configfs.c +++ b/drivers/target/target_core_fabric_configfs.c @@ -689,6 +689,14 @@ 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) diff --git a/drivers/usb/gadget/function/f_tcm.c b/drivers/usb/gadget/function/f_tcm.c index 5b31dc9db9bf..cff26812bc04 100644 --- a/drivers/usb/gadget/function/f_tcm.c +++ b/drivers/usb/gadget/function/f_tcm.c @@ -1709,7 +1709,7 @@ static const struct target_core_fabric_ops usbg_ops = { .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, diff --git a/include/target/target_core_fabric.h b/include/target/target_core_fabric.h index b188b1e90e1e..43999aefb536 100644 --- 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 *); |