We can't rely on the contents of the devres list during
spi_unregister_controller(), as the list is already torn down at the
time we perform devres_find() for devm_spi_release_controller. This
causes devices registered with devm_spi_alloc_{master,slave}() to be
mistakenly identified as legacy, non-devm managed devices and have their
reference counters decremented below 0.
------------[ cut here ]------------
WARNING: CPU: 1 PID: 660 at lib/refcount.c:28 refcount_warn_saturate+0x108/0x174
[<
b0396f04>] (refcount_warn_saturate) from [<
b03c56a4>] (kobject_put+0x90/0x98)
[<
b03c5614>] (kobject_put) from [<
b0447b4c>] (put_device+0x20/0x24)
r4:
b6700140
[<
b0447b2c>] (put_device) from [<
b07515e8>] (devm_spi_release_controller+0x3c/0x40)
[<
b07515ac>] (devm_spi_release_controller) from [<
b045343c>] (release_nodes+0x84/0xc4)
r5:
b6700180 r4:
b6700100
[<
b04533b8>] (release_nodes) from [<
b0454160>] (devres_release_all+0x5c/0x60)
r8:
b1638c54 r7:
b117ad94 r6:
b1638c10 r5:
b117ad94 r4:
b163dc10
[<
b0454104>] (devres_release_all) from [<
b044e41c>] (__device_release_driver+0x144/0x1ec)
r5:
b117ad94 r4:
b163dc10
[<
b044e2d8>] (__device_release_driver) from [<
b044f70c>] (device_driver_detach+0x84/0xa0)
r9:
00000000 r8:
00000000 r7:
b117ad94 r6:
b163dc54 r5:
b1638c10 r4:
b163dc10
[<
b044f688>] (device_driver_detach) from [<
b044d274>] (unbind_store+0xe4/0xf8)
Instead, determine the devm allocation state as a flag on the
controller which is guaranteed to be stable during cleanup.
Fixes:
5e844cc37a5c ("spi: Introduce device-managed SPI controller allocation")
Signed-off-by: William A. Kennington III <wak@google.com>
Link: https://lore.kernel.org/r/20210407095527.2771582-1-wak@google.com
Signed-off-by: Mark Brown <broonie@kernel.org>
ctlr = __spi_alloc_controller(dev, size, slave);
if (ctlr) {
+ ctlr->devm_allocated = true;
*ptr = ctlr;
devres_add(dev, ptr);
} else {
}
EXPORT_SYMBOL_GPL(devm_spi_register_controller);
-static int devm_spi_match_controller(struct device *dev, void *res, void *ctlr)
-{
- return *(struct spi_controller **)res == ctlr;
-}
-
static int __unregister(struct device *dev, void *null)
{
spi_unregister_device(to_spi_device(dev));
/* Release the last reference on the controller if its driver
* has not yet been converted to devm_spi_alloc_master/slave().
*/
- if (!devres_find(ctlr->dev.parent, devm_spi_release_controller,
- devm_spi_match_controller, ctlr))
+ if (!ctlr->devm_allocated)
put_device(&ctlr->dev);
/* free bus id */
#define SPI_MASTER_GPIO_SS BIT(5) /* GPIO CS must select slave */
+ /* flag indicating this is a non-devres managed controller */
+ bool devm_allocated;
+
/* flag indicating this is an SPI slave controller */
bool slave;