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Since forcewake uses a reference counting get/put model, there are many
places where we need to be careful to drop the forcewake reference when
bailing out of a function early on an error path. Add scope-based
cleanup options that can be used in place of explicit get/put to help
prevent mistakes in this area.
Examples:
CLASS(xe_force_wake, fw_ref)(gt_to_fw(gt), XE_FW_GT);
Obtain forcewake on the XE_FW_GT domain and hold it until the
end of the current block. The wakeref will be dropped
automatically when the current scope is exited by any means
(return, break, reaching the end of the block, etc.).
xe_with_force_wake(fw_ref, gt_to_fw(ss->gt), XE_FORCEWAKE_ALL) {
...
}
Hold all forcewake domains for the following block. As with the
CLASS usage, forcewake will be dropped automatically when the
block is exited by any means.
Use of these cleanup helpers should allow us to remove some ugly
goto-based error handling and help avoid mistakes in functions with lots
of early error exits.
An 'xe_force_wake_release_only' class is also added for cases where a
forcewake reference is passed in from another function and the current
function is responsible for releasing it in every flow and error path.
v2:
- Create a separate constructor that just wraps xe_force_wake_get for
use in the class. This eliminates the need to update the signature
of xe_force_wake_get(). (Michal)
v3:
- Wrap xe_with_force_wake's 'done' marker in __UNIQUE_ID. (Gustavo)
- Add a note to xe_force_wake_get()'s kerneldoc explaining that
scope-based cleanup is preferred when possible. (Gustavo)
- Add an xe_force_wake_release_only class. (Gustavo)
v4:
- Add NULL check on fw in release_only variant. (Gustavo)
Cc: Michal Wajdeczko <michal.wajdeczko@intel.com>
Cc: Gustavo Sousa <gustavo.sousa@intel.com>
Reviewed-by: Gustavo Sousa <gustavo.sousa@intel.com>
Link: https://patch.msgid.link/20251118164338.3572146-30-matthew.d.roper@intel.com
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
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 reStructuredText 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.