[PATCH 4.9 04/62] usb: hub: Fix usb enumeration issue due to address0 race
From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Date: 2021-12-06 15:04:03
Also in:
lkml
From: Mathias Nyman <redacted>
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: <redacted>
Fixes: 638139eb95d2 ("usb: hub: allow to process more usb hub events in parallel")
Signed-off-by: Mathias Nyman <redacted>
Link: https://lore.kernel.org/r/20211115221630.871204-1-mathias.nyman@linux.intel.com (local)
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
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@@ -4460,8 +4460,6 @@ 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);
@@ -4748,7 +4746,6 @@ fail: hub_port_disable(hub, port1, 0); update_devnum(udev, devnum); /* for disconnect processing */ } - mutex_unlock(hcd->address0_mutex); return retval; }
@@ -4893,6 +4890,9 @@ static void hub_port_connect(struct usb_ unit_load = 100; status = 0; + + mutex_lock(hcd->address0_mutex); + for (i = 0; i < SET_CONFIG_TRIES; i++) { /* reallocate for each attempt, since references
@@ -4929,6 +4929,8 @@ 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);
@@ -5017,6 +5019,7 @@ 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);
@@ -5043,6 +5046,8 @@ 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)
@@ -5572,6 +5577,8 @@ static int usb_reset_and_verify_device(s bos = udev->bos; udev->bos = NULL; + mutex_lock(hcd->address0_mutex); + for (i = 0; i < SET_CONFIG_TRIES; ++i) { /* ep0 maxpacket size may change; let the HCD know about it.
@@ -5581,6 +5588,7 @@ 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;