49e74c8f9a
Only along the submission path can we guarantee that the locked request
is indeed from a foreign engine, and so the nesting of engine/rq is
permissible. On the submission tasklet (process_csb()), we may find
ourselves competing with the normal nesting of rq/engine, invalidating
our nesting. As we only use the spinlock for debug purposes, skip the
debug if we cannot acquire the spinlock for safe validation - catching
99% of the bugs is better than causing a hard lockup.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Fixes: c95d31c3df1b ("drm/i915/execlists: Lock the request while validating it during promotion")
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191203152631.3107653-2-chris@chris-wilson.co.uk
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.