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authorMatthias Kaehlcke <mka@chromium.org>2023-01-10 20:32:53 +0300
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2023-01-24 09:24:35 +0300
commitbab5687f4d1b01da8f2bdbcd38d7863ed17be555 (patch)
tree589ea8064b9c996e48d8ac6a2e655ca10ed59f52 /drivers/usb/misc
parentcbb0da62573c8fb8a21de8fde272acc8756c4fb4 (diff)
downloadlinux-bab5687f4d1b01da8f2bdbcd38d7863ed17be555.tar.xz
usb: misc: onboard_hub: Move 'attach' work to the driver
commit cde37881e2e14590675d0acdfbad408300d9ca95 upstream. Currently each onboard_hub platform device owns an 'attach' work, which is scheduled when the device probes. With this deadlocks have been reported on a Raspberry Pi 3 B+ [1], which has nested onboard hubs. The flow of the deadlock is something like this (with the onboard_hub driver built as a module) [2]: - USB root hub is instantiated - core hub driver calls onboard_hub_create_pdevs(), which creates the 'raw' platform device for the 1st level hub - 1st level hub is probed by the core hub driver - core hub driver calls onboard_hub_create_pdevs(), which creates the 'raw' platform device for the 2nd level hub - onboard_hub platform driver is registered - platform device for 1st level hub is probed - schedules 'attach' work - platform device for 2nd level hub is probed - schedules 'attach' work - onboard_hub USB driver is registered - device (and parent) lock of hub is held while the device is re-probed with the onboard_hub driver - 'attach' work (running in another thread) calls driver_attach(), which blocks on one of the hub device locks - onboard_hub_destroy_pdevs() is called by the core hub driver when one of the hubs is detached - destroying the pdevs invokes onboard_hub_remove(), which waits for the 'attach' work to complete - waits forever, since the 'attach' work can't acquire the device lock Use a single work struct for the driver instead of having a work struct per onboard hub platform driver instance. With that it isn't necessary to cancel the work in onboard_hub_remove(), which fixes the deadlock. The work is only cancelled when the driver is unloaded. [1] https://lore.kernel.org/r/d04bcc45-3471-4417-b30b-5cf9880d785d@i2se.com/ [2] https://lore.kernel.org/all/Y6OrGbqaMy2iVDWB@google.com/ Cc: stable@vger.kernel.org Fixes: 8bc063641ceb ("usb: misc: Add onboard_usb_hub driver") Link: https://lore.kernel.org/r/d04bcc45-3471-4417-b30b-5cf9880d785d@i2se.com/ Link: https://lore.kernel.org/all/Y6OrGbqaMy2iVDWB@google.com/ Reported-by: Stefan Wahren <stefan.wahren@i2se.com> Signed-off-by: Matthias Kaehlcke <mka@chromium.org> Link: https://lore.kernel.org/r/20230110172954.v2.2.I16b51f32db0c32f8a8532900bfe1c70c8572881a@changeid Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/usb/misc')
-rw-r--r--drivers/usb/misc/onboard_usb_hub.c12
1 files changed, 6 insertions, 6 deletions
diff --git a/drivers/usb/misc/onboard_usb_hub.c b/drivers/usb/misc/onboard_usb_hub.c
index 03d5f4d5b1a5..044e75ad4d20 100644
--- a/drivers/usb/misc/onboard_usb_hub.c
+++ b/drivers/usb/misc/onboard_usb_hub.c
@@ -27,7 +27,10 @@
#include "onboard_usb_hub.h"
+static void onboard_hub_attach_usb_driver(struct work_struct *work);
+
static struct usb_device_driver onboard_hub_usbdev_driver;
+static DECLARE_WORK(attach_usb_driver_work, onboard_hub_attach_usb_driver);
/************************** Platform driver **************************/
@@ -45,7 +48,6 @@ struct onboard_hub {
bool is_powered_on;
bool going_away;
struct list_head udev_list;
- struct work_struct attach_usb_driver_work;
struct mutex lock;
};
@@ -271,8 +273,7 @@ static int onboard_hub_probe(struct platform_device *pdev)
* This needs to be done deferred to avoid self-deadlocks on systems
* with nested onboard hubs.
*/
- INIT_WORK(&hub->attach_usb_driver_work, onboard_hub_attach_usb_driver);
- schedule_work(&hub->attach_usb_driver_work);
+ schedule_work(&attach_usb_driver_work);
return 0;
}
@@ -285,9 +286,6 @@ static int onboard_hub_remove(struct platform_device *pdev)
hub->going_away = true;
- if (&hub->attach_usb_driver_work != current_work())
- cancel_work_sync(&hub->attach_usb_driver_work);
-
mutex_lock(&hub->lock);
/* unbind the USB devices to avoid dangling references to this device */
@@ -447,6 +445,8 @@ static void __exit onboard_hub_exit(void)
{
usb_deregister_device_driver(&onboard_hub_usbdev_driver);
platform_driver_unregister(&onboard_hub_driver);
+
+ cancel_work_sync(&attach_usb_driver_work);
}
module_exit(onboard_hub_exit);