f924211946
commit 7b960c967f2aa01ab8f45c5a0bd78e754cffdeee upstream.
Commit 05b35e7eb9a1 ("smsc95xx: add phylib support") amended
smsc95xx_resume() to call phy_init_hw(). That function waits for the
device to runtime resume even though it is placed in the runtime resume
path, causing a deadlock.
The problem is that phy_init_hw() calls down to smsc95xx_mdiobus_read(),
which never uses the _nopm variant of usbnet_read_cmd().
Commit b4df480f68ae ("usbnet: smsc95xx: add reset_resume function with
reset operation") causes a similar deadlock on resume if the device was
already runtime suspended when entering system sleep:
That's because the commit introduced smsc95xx_reset_resume(), which
calls down to smsc95xx_reset(), which neglects to use _nopm accessors.
Fix by auto-detecting whether a device access is performed by the
suspend/resume task_struct and use the _nopm variant if so. This works
because the PM core guarantees that suspend/resume callbacks are run in
task context.
Stacktrace for posterity:
INFO: task kworker/2:1:49 blocked for more than 122 seconds.
Workqueue: usb_hub_wq hub_event
schedule
rpm_resume
__pm_runtime_resume
usb_autopm_get_interface
usbnet_read_cmd
__smsc95xx_read_reg
__smsc95xx_phy_wait_not_busy
__smsc95xx_mdio_read
smsc95xx_mdiobus_read
__mdiobus_read
mdiobus_read
smsc_phy_reset
phy_init_hw
smsc95xx_resume
usb_resume_interface
usb_resume_both
usb_runtime_resume
__rpm_callback
rpm_callback
rpm_resume
__pm_runtime_resume
usb_autoresume_device
hub_event
process_one_work
Fixes: b4df480f68ae ("usbnet: smsc95xx: add reset_resume function with reset operation")
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Cc: stable@vger.kernel.org # v3.16+
Cc: Andre Edich <andre.edich@microchip.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
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https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.