From: William A. Kennington III wak@google.com
[ Upstream commit 794aaf01444d4e765e2b067cba01cc69c1c68ed9 ]
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 Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/spi/spi.c | 9 ++------- include/linux/spi/spi.h | 3 +++ 2 files changed, 5 insertions(+), 7 deletions(-)
diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c index ca9970a63fdf..da71a53b0df7 100644 --- a/drivers/spi/spi.c +++ b/drivers/spi/spi.c @@ -2076,6 +2076,7 @@ struct spi_controller *__devm_spi_alloc_controller(struct device *dev,
ctlr = __spi_alloc_controller(dev, size, slave); if (ctlr) { + ctlr->devm_allocated = true; *ptr = ctlr; devres_add(dev, ptr); } else { @@ -2304,11 +2305,6 @@ int devm_spi_register_controller(struct device *dev, } 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)); @@ -2353,8 +2349,7 @@ void spi_unregister_controller(struct spi_controller *ctlr) /* 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 */ diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h index 715bd276a041..a8f6606dd498 100644 --- a/include/linux/spi/spi.h +++ b/include/linux/spi/spi.h @@ -452,6 +452,9 @@ struct spi_controller {
#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;