driver core: have match() callback in struct bus_type take a const *

In the match() callback, the struct device_driver * should not be
changed, so change the function callback to be a const *.  This is one
step of many towards making the driver core safe to have struct
device_driver in read-only memory.

Because the match() callback is in all busses, all busses are modified
to handle this properly.  This does entail switching some container_of()
calls to container_of_const() to properly handle the constant *.

For some busses, like PCI and USB and HV, the const * is cast away in
the match callback as those busses do want to modify those structures at
this point in time (they have a local lock in the driver structure.)
That will have to be changed in the future if they wish to have their
struct device * in read-only-memory.

Cc: Rafael J. Wysocki <rafael@kernel.org>
Reviewed-by: Alex Elder <elder@kernel.org>
Acked-by: Sumit Garg <sumit.garg@linaro.org>
Link: https://lore.kernel.org/r/2024070136-wrongdoer-busily-01e8@gregkh
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 2 insertions, 4 deletions

diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h
index e8e1e798924f..3fc559686d38 100644
--- a/include/linux/spi/spi.h
+++ b/include/linux/spi/spi.h
@@ -351,10 +351,8 @@ struct spi_driver {
 	struct device_driver	driver;
 };
 
-static inline struct spi_driver *to_spi_driver(struct device_driver *drv)
-{
-	return drv ? container_of(drv, struct spi_driver, driver) : NULL;
-}
+#define to_spi_driver(__drv)   \
+	( __drv ? container_of_const(__drv, struct spi_driver, driver) : NULL )
 
 extern int __spi_register_driver(struct module *owner, struct spi_driver *sdrv);