ca52aa4c60
Adding spi_optimize_message() broke the spi-mux driver because it calls spi_async() from it's transfer_one_message() callback. This resulted in passing an incorrectly optimized message to the controller. For example, if the underlying controller has an optimize_message() callback, this would have not been called and can cause a crash when the underlying controller driver tries to transfer the message. Also, since the spi-mux driver swaps out the controller pointer by replacing msg->spi, __spi_unoptimize_message() was being called with a different controller than the one used in __spi_optimize_message(). This could cause a crash when attempting to free the message resources when __spi_unoptimize_message() is called in spi_finalize_current_message() since it is being called with a controller that did not allocate the resources. This is fixed by adding a defer_optimize_message flag for controllers. This flag causes all of the spi_[maybe_][un]optimize_message() calls to be a no-op (other than attaching a pointer to the spi device to the message). This allows the spi-mux driver to pass an unmodified message to spi_async() in spi_mux_transfer_one_message() after the spi device has been swapped out. This causes __spi_optimize_message() and __spi_unoptimize_message() to be called only once per message and with the correct/same controller in each case. Reported-by: Oleksij Rempel <o.rempel@pengutronix.de> Closes: https://lore.kernel.org/linux-spi/Zn6HMrYG2b7epUxT@pengutronix.de/ Reported-by: Marc Kleine-Budde <mkl@pengutronix.de> Closes: https://lore.kernel.org/linux-spi/20240628-awesome-discerning-bear-1621f9-mkl@pengutronix.de/ Fixes: 7b1d87af14d9 ("spi: add spi_optimize_message() APIs") Signed-off-by: David Lechner <dlechner@baylibre.com> Link: https://patch.msgid.link/20240708-spi-mux-fix-v1-2-6c8845193128@baylibre.com Signed-off-by: Mark Brown <broonie@kernel.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 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.