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The expected flow of operations when using PXP is to query the PXP status and wait for it to transition to "ready" before attempting to create an exec_queue. This flow is followed by the Mesa driver, but there is no guarantee that an incorrectly coded (or malicious) app will not attempt to create the queue first without querying the status. Therefore, we need to clarify what the expected behavior of the queue creation ioctl is in this scenario. Currently, the ioctl always fails with an -EBUSY code no matter the error, but for consistency it is better to distinguish between "failed to init" (-EIO) and "not ready" (-EBUSY), the same way the query ioctl does. Note that, while this is a change in the return code of an ioctl, the behavior of the ioctl in this particular corner case was not clearly spec'd, so no one should have been relying on it (and we know that Mesa, which is the only known userspace for this, didn't). v2: Minor rework of the doc (Rodrigo) Fixes:72d479601d("drm/xe/pxp/uapi: Add userspace and LRC support for PXP-using queues") Signed-off-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com> Cc: John Harrison <John.C.Harrison@Intel.com> Cc: José Roberto de Souza <jose.souza@intel.com> Reviewed-by: José Roberto de Souza <jose.souza@intel.com> Reviewed-by: John Harrison <John.C.Harrison@Intel.com> Acked-by: Rodrigo Vivi <rodrigo.vivi@intel.com> Link: https://lore.kernel.org/r/20250522225401.3953243-7-daniele.ceraolospurio@intel.com (cherry picked from commit21784ca960) Signed-off-by: Thomas Hellström <thomas.hellstrom@linux.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.