This is a note to let you know that I've just added the patch titled
spi: add defer_optimize_message controller flag
to the 6.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
spi-add-defer_optimize_message-controller-flag.patch
and it can be found in the queue-6.9 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit bd18cef36942a09fbb1dbf4748bb8afce992b43b
Author: David Lechner <dlechner@xxxxxxxxxxxx>
Date: Mon Jul 8 20:05:29 2024 -0500
spi: add defer_optimize_message controller flag
[ Upstream commit ca52aa4c60f76566601b42e935b8a78f0fb4f8eb ]
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@xxxxxxxxxxxxxx>
Closes: https://lore.kernel.org/linux-spi/Zn6HMrYG2b7epUxT@xxxxxxxxxxxxxx/
Reported-by: Marc Kleine-Budde <mkl@xxxxxxxxxxxxxx>
Closes: https://lore.kernel.org/linux-spi/20240628-awesome-discerning-bear-1621f9-mkl@xxxxxxxxxxxxxx/
Fixes: 7b1d87af14d9 ("spi: add spi_optimize_message() APIs")
Signed-off-by: David Lechner <dlechner@xxxxxxxxxxxx>
Link: https://patch.msgid.link/20240708-spi-mux-fix-v1-2-6c8845193128@xxxxxxxxxxxx
Signed-off-by: Mark Brown <broonie@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/spi/spi-mux.c b/drivers/spi/spi-mux.c
index bd988f53753e2..031b5795d1060 100644
--- a/drivers/spi/spi-mux.c
+++ b/drivers/spi/spi-mux.c
@@ -162,6 +162,7 @@ static int spi_mux_probe(struct spi_device *spi)
ctlr->bus_num = -1;
ctlr->dev.of_node = spi->dev.of_node;
ctlr->must_async = true;
+ ctlr->defer_optimize_message = true;
ret = devm_spi_register_controller(&spi->dev, ctlr);
if (ret)
diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index a1958e86f75c8..9304fd03bf764 100644
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -2137,7 +2137,8 @@ static void __spi_unoptimize_message(struct spi_message *msg)
*/
static void spi_maybe_unoptimize_message(struct spi_message *msg)
{
- if (!msg->pre_optimized && msg->optimized)
+ if (!msg->pre_optimized && msg->optimized &&
+ !msg->spi->controller->defer_optimize_message)
__spi_unoptimize_message(msg);
}
@@ -4285,6 +4286,11 @@ static int __spi_optimize_message(struct spi_device *spi,
static int spi_maybe_optimize_message(struct spi_device *spi,
struct spi_message *msg)
{
+ if (spi->controller->defer_optimize_message) {
+ msg->spi = spi;
+ return 0;
+ }
+
if (msg->pre_optimized)
return 0;
@@ -4315,6 +4321,13 @@ int spi_optimize_message(struct spi_device *spi, struct spi_message *msg)
{
int ret;
+ /*
+ * Pre-optimization is not supported and optimization is deferred e.g.
+ * when using spi-mux.
+ */
+ if (spi->controller->defer_optimize_message)
+ return 0;
+
ret = __spi_optimize_message(spi, msg);
if (ret)
return ret;
@@ -4341,6 +4354,9 @@ EXPORT_SYMBOL_GPL(spi_optimize_message);
*/
void spi_unoptimize_message(struct spi_message *msg)
{
+ if (msg->spi->controller->defer_optimize_message)
+ return;
+
__spi_unoptimize_message(msg);
msg->pre_optimized = false;
}
diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h
index c459809efee4f..64a4deb18dd00 100644
--- a/include/linux/spi/spi.h
+++ b/include/linux/spi/spi.h
@@ -532,6 +532,9 @@ extern struct spi_device *spi_new_ancillary_device(struct spi_device *spi, u8 ch
* @queue_empty: signal green light for opportunistically skipping the queue
* for spi_sync transfers.
* @must_async: disable all fast paths in the core
+ * @defer_optimize_message: set to true if controller cannot pre-optimize messages
+ * and needs to defer the optimization step until the message is actually
+ * being transferred
*
* Each SPI controller can communicate with one or more @spi_device
* children. These make a small bus, sharing MOSI, MISO and SCK signals
@@ -775,6 +778,7 @@ struct spi_controller {
/* Flag for enabling opportunistic skipping of the queue in spi_sync */
bool queue_empty;
bool must_async;
+ bool defer_optimize_message;
};
static inline void *spi_controller_get_devdata(struct spi_controller *ctlr)
