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0ff0705a2e
Lockdep reports an AB BA lock inversion between ucsi_init() and ucsi_handle_connector_change(): AB order: 1. ucsi_init takes ucsi->ppm_lock (it runs with that locked for the duration of the function) 2. usci_init eventually end up calling ucsi_register_displayport, which takes ucsi_connector->lock BA order: 1. ucsi_handle_connector_change work is started, takes ucsi_connector->lock 2. ucsi_handle_connector_change calls ucsi_send_command which takes ucsi->ppm_lock The ppm_lock really only needs to be hold during 2 functions: ucsi_reset_ppm() and ucsi_run_command(). This commit fixes the AB BA lock inversion by making ucsi_init drop the ucsi->ppm_lock before it starts registering ports; and replacing any ucsi_run_command() calls after this point with ucsi_send_command() (which is a wrapper around run_command taking the lock while handling the command). Some of the replacing of ucsi_run_command with ucsi_send_command in the helpers used during port registration also fixes a number of code paths after registration which call ucsi_run_command() without holding the ppm_lock: 1. ucsi_altmode_update_active() call in ucsi/displayport.c 2. ucsi_register_altmodes() call from ucsi_handle_connector_change() (through ucsi_partner_change()) Cc: stable@vger.kernel.org Signed-off-by: Hans de Goede <hdegoede@redhat.com> Acked-by: Heikki Krogerus <heikki.krogerus@linux.intel.com> Reviewed-by: Guenter Roeck <linux@roeck-us.net> Link: https://lore.kernel.org/r/20200809141904.4317-2-hdegoede@redhat.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
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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.