[PATCH] usb: mtu3: Prevent dr_work rearm during teardown

[Myeonghun Pak <mhun512@gmail.com>]

ssusb_otg_switch_exit() drains otg_sx->dr_work with
cancel_work_sync().  A later queue_work() from ssusb_set_mode()
arms it again.  Callers that outlive the cancel are the role-switch
store, ssusb_id_notifier(), and the manual-DRD debugfs mode file.
The role switch is unregistered on the next line.  The extcon
notifier is devm-managed, and extcon_sync() invokes it after
dropping edev->lock, so unregister is not a barrier.  The mode file
is removed only after ssusb_gadget_exit(), ssusb_host_exit() and
ssusb_rscs_exit().

The late work calls mtu3_stop() or mtu3_start(), writes IPPC
registers and calls pm_runtime_get_sync().  dr_work is embedded in
the devm_kzalloc()ed struct ssusb_mtk.

disable_work_sync() rejects a later queue_work() and drains an item
already pending or running.  Exit does not enable the work again.

This issue was identified during our ongoing static-analysis research
while reviewing kernel code.

Fixes: 18cfd7b85ced ("usb: mtu3: rebuild role switch flow of extcon")
Cc: stable@vger.kernel.org # 6.10+
Assisted-by: LLM
Co-developed-by: Ijae Kim <ae878000@gmail.com>
Signed-off-by: Ijae Kim <ae878000@gmail.com>
Signed-off-by: Myeonghun Pak <mhun512@gmail.com>
---
 drivers/usb/mtu3/mtu3_dr.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/usb/mtu3/mtu3_dr.c b/drivers/usb/mtu3/mtu3_dr.c
index ffa5b9401dad..262922057b13 100644
--- a/drivers/usb/mtu3/mtu3_dr.c
+++ b/drivers/usb/mtu3/mtu3_dr.c
@@ -326,6 +326,6 @@ void ssusb_otg_switch_exit(struct ssusb_mtk *ssusb)
 {
 	struct otg_switch_mtk *otg_sx = &ssusb->otg_switch;
 
-	cancel_work_sync(&otg_sx->dr_work);
+	disable_work_sync(&otg_sx->dr_work);
 	usb_role_switch_unregister(otg_sx->role_sw);
 }

base-commit: 238650ef6c7c7cca08e032527329424c9fbd70e5
-- 
2.53.0