This is a note to let you know that I've just added the patch titled usb: hub: Fix usb enumeration issue due to address0 race to the 5.10-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: usb-hub-fix-usb-enumeration-issue-due-to-address0-race.patch and it can be found in the queue-5.10 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From 6ae6dc22d2d1ce6aa77a6da8a761e61aca216f8b Mon Sep 17 00:00:00 2001 From: Mathias Nyman <mathias.nyman@xxxxxxxxxxxxxxx> Date: Tue, 16 Nov 2021 00:16:30 +0200 Subject: usb: hub: Fix usb enumeration issue due to address0 race From: Mathias Nyman <mathias.nyman@xxxxxxxxxxxxxxx> commit 6ae6dc22d2d1ce6aa77a6da8a761e61aca216f8b upstream. xHC hardware can only have one slot in default state with address 0 waiting for a unique address at a time, otherwise "undefined behavior may occur" according to xhci spec 5.4.3.4 The address0_mutex exists to prevent this across both xhci roothubs. If hub_port_init() fails, it may unlock the mutex and exit with a xhci slot in default state. If the other xhci roothub calls hub_port_init() at this point we end up with two slots in default state. Make sure the address0_mutex protects the slot default state across hub_port_init() retries, until slot is addressed or disabled. Note, one known minor case is not fixed by this patch. If device needs to be reset during resume, but fails all hub_port_init() retries in usb_reset_and_verify_device(), then it's possible the slot is still left in default state when address0_mutex is unlocked. Cc: <stable@xxxxxxxxxxxxxxx> Fixes: 638139eb95d2 ("usb: hub: allow to process more usb hub events in parallel") Signed-off-by: Mathias Nyman <mathias.nyman@xxxxxxxxxxxxxxx> Link: https://lore.kernel.org/r/20211115221630.871204-1-mathias.nyman@xxxxxxxxxxxxxxx Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/usb/core/hub.c | 14 +++++++++++--- 1 file changed, 11 insertions(+), 3 deletions(-) --- a/drivers/usb/core/hub.c +++ b/drivers/usb/core/hub.c @@ -4628,8 +4628,6 @@ hub_port_init(struct usb_hub *hub, struc if (oldspeed == USB_SPEED_LOW) delay = HUB_LONG_RESET_TIME; - mutex_lock(hcd->address0_mutex); - /* Reset the device; full speed may morph to high speed */ /* FIXME a USB 2.0 device may morph into SuperSpeed on reset. */ retval = hub_port_reset(hub, port1, udev, delay, false); @@ -4940,7 +4938,6 @@ fail: hub_port_disable(hub, port1, 0); update_devnum(udev, devnum); /* for disconnect processing */ } - mutex_unlock(hcd->address0_mutex); return retval; } @@ -5170,6 +5167,9 @@ static void hub_port_connect(struct usb_ unit_load = 100; status = 0; + + mutex_lock(hcd->address0_mutex); + for (i = 0; i < PORT_INIT_TRIES; i++) { /* reallocate for each attempt, since references @@ -5206,6 +5206,8 @@ static void hub_port_connect(struct usb_ if (status < 0) goto loop; + mutex_unlock(hcd->address0_mutex); + if (udev->quirks & USB_QUIRK_DELAY_INIT) msleep(2000); @@ -5294,6 +5296,7 @@ static void hub_port_connect(struct usb_ loop_disable: hub_port_disable(hub, port1, 1); + mutex_lock(hcd->address0_mutex); loop: usb_ep0_reinit(udev); release_devnum(udev); @@ -5320,6 +5323,8 @@ loop: } done: + mutex_unlock(hcd->address0_mutex); + hub_port_disable(hub, port1, 1); if (hcd->driver->relinquish_port && !hub->hdev->parent) { if (status != -ENOTCONN && status != -ENODEV) @@ -5839,6 +5844,8 @@ static int usb_reset_and_verify_device(s bos = udev->bos; udev->bos = NULL; + mutex_lock(hcd->address0_mutex); + for (i = 0; i < PORT_INIT_TRIES; ++i) { /* ep0 maxpacket size may change; let the HCD know about it. @@ -5848,6 +5855,7 @@ static int usb_reset_and_verify_device(s if (ret >= 0 || ret == -ENOTCONN || ret == -ENODEV) break; } + mutex_unlock(hcd->address0_mutex); if (ret < 0) goto re_enumerate; Patches currently in stable-queue which might be from mathias.nyman@xxxxxxxxxxxxxxx are queue-5.10/usb-hub-fix-locking-issues-with-address0_mutex.patch queue-5.10/usb-hub-fix-usb-enumeration-issue-due-to-address0-race.patch