[PATCH] usb: hub: Fix usb enumeration issue due to address0 race
From: Mathias Nyman <hidden>
Date: 2021-11-15 22:29:24
Also in:
stable
Subsystem:
the rest, usb subsystem · Maintainers:
Linus Torvalds, Greg Kroah-Hartman
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: <redacted> Signed-off-by: Mathias Nyman <redacted> --- drivers/usb/core/hub.c | 14 +++++++++++--- 1 file changed, 11 insertions(+), 3 deletions(-)
diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
index 86658a81d284..00c3506324e4 100644
--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c@@ -4700,8 +4700,6 @@ hub_port_init(struct usb_hub *hub, struct usb_device *udev, int port1, 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);
@@ -5016,7 +5014,6 @@ hub_port_init(struct usb_hub *hub, struct usb_device *udev, int port1, hub_port_disable(hub, port1, 0); update_devnum(udev, devnum); /* for disconnect processing */ } - mutex_unlock(hcd->address0_mutex); return retval; }
@@ -5246,6 +5243,9 @@ static void hub_port_connect(struct usb_hub *hub, int port1, u16 portstatus, unit_load = 100; status = 0; + + mutex_lock(hcd->address0_mutex); + for (i = 0; i < PORT_INIT_TRIES; i++) { /* reallocate for each attempt, since references
@@ -5282,6 +5282,8 @@ static void hub_port_connect(struct usb_hub *hub, int port1, u16 portstatus, if (status < 0) goto loop; + mutex_unlock(hcd->address0_mutex); + if (udev->quirks & USB_QUIRK_DELAY_INIT) msleep(2000);
@@ -5370,6 +5372,7 @@ static void hub_port_connect(struct usb_hub *hub, int port1, u16 portstatus, loop_disable: hub_port_disable(hub, port1, 1); + mutex_lock(hcd->address0_mutex); loop: usb_ep0_reinit(udev); release_devnum(udev);
@@ -5396,6 +5399,8 @@ static void hub_port_connect(struct usb_hub *hub, int port1, u16 portstatus, } 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)
@@ -5915,6 +5920,8 @@ static int usb_reset_and_verify_device(struct usb_device *udev) 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.
@@ -5924,6 +5931,7 @@ static int usb_reset_and_verify_device(struct usb_device *udev) if (ret >= 0 || ret == -ENOTCONN || ret == -ENODEV) break; } + mutex_unlock(hcd->address0_mutex); if (ret < 0) goto re_enumerate;
--
2.25.1