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While testing Fabio's patch I hit lockdep warning about possible deadlock: [ 252.063305] WARNING: possible recursive locking detected [ 252.063642] 5.14.0+ #9 Tainted: G C [ 252.063946] -------------------------------------------- [ 252.064282] ip/335 is trying to acquire lock: [ 252.064560] ffff888009ebad28 (pmutex){+.+.}-{4:4}, at: usbctrl_vendorreq+0xc5/0x4a0 [r8188eu] [ 252.065168] [ 252.065168] but task is already holding lock: [ 252.065536] ffffffffc021b3b8 (pmutex){+.+.}-{4:4}, at: netdev_open+0x3a/0x5f [r8188eu] [ 252.066085] [ 252.066085] other info that might help us debug this: [ 252.066494] Possible unsafe locking scenario: [ 252.066494] [ 252.066866] CPU0 [ 252.067025] ---- [ 252.067184] lock(pmutex); [ 252.067367] lock(pmutex); There is one problem with this warning: there is no pmutex in this driver, *BUT* all mutexes are initialized via private _rtw_mutex_init API, which had struct mutex *pmutex argument. So, all mutexes in this driver had same name in lockdep map. Of course, lockdep will complain about any nested locking. Fix it by open-coding _rtw_mutex_{init,free} wrappers, because we do not need them at all. Cc: Fabio M. De Francesco <fmdefrancesco@gmail.com> Signed-off-by: Pavel Skripkin <paskripkin@gmail.com> Link: https://lore.kernel.org/r/20210904124747.30050-1-paskripkin@gmail.com 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
``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.