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[ Upstream commit7b960c967f] Commit05b35e7eb9("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(). Commitb4df480f68("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:b4df480f68("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: Sasha Levin <sashal@kernel.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
``make pdfdocs``. The formatted documentation can also be read online at:
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.