Revert "spi: Fix deadlock when adding SPI controllers on SPI buses" […

…5.4.286] This reverts commit aa3f3d7bef59583f2d3234173105a27ff61ef8fe which is commit 6098475d4cb48d821bdf453c61118c56e26294f0 upstream. It breaks the Android kernel abi and can be brought back in the future in an abi-safe way if it is really needed. Bug: 161946584 Change-Id: I2bd07f43254864be68c6426dc3215dcd60aa0516 Signed-off-by: Greg Kroah-Hartman <[email protected]>
psndna88 · Nov 26, 2024 · 9688ed2 · 9688ed2
1 parent 6e58fa8
commit 9688ed2
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Showing 2 changed files with 9 additions and 7 deletions.
diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
@@ -472,6 +472,12 @@ static LIST_HEAD(spi_controller_list);
  */
 static DEFINE_MUTEX(board_lock);
 
+/*
+ * Prevents addition of devices with same chip select and
+ * addition of devices below an unregistering controller.
+ */
+static DEFINE_MUTEX(spi_add_lock);
+
 /**
  * spi_alloc_device - Allocate a new SPI device
  * @ctlr: Controller to which device is connected
@@ -574,7 +580,7 @@ int spi_add_device(struct spi_device *spi)
 	 * chipselect **BEFORE** we call setup(), else we'll trash
 	 * its configuration.  Lock against concurrent add() calls.
 	 */
-	mutex_lock(&ctlr->add_lock);
+	mutex_lock(&spi_add_lock);
 
 	status = bus_for_each_dev(&spi_bus_type, NULL, spi, spi_dev_check);
 	if (status) {
@@ -618,7 +624,7 @@ int spi_add_device(struct spi_device *spi)
 	}
 
 done:
-	mutex_unlock(&ctlr->add_lock);
+	mutex_unlock(&spi_add_lock);
 	return status;
 }
 EXPORT_SYMBOL_GPL(spi_add_device);
@@ -2505,7 +2511,6 @@ int spi_register_controller(struct spi_controller *ctlr)
 	spin_lock_init(&ctlr->bus_lock_spinlock);
 	mutex_init(&ctlr->bus_lock_mutex);
 	mutex_init(&ctlr->io_mutex);
-	mutex_init(&ctlr->add_lock);
 	ctlr->bus_lock_flag = 0;
 	init_completion(&ctlr->xfer_completion);
 	if (!ctlr->max_dma_len)
@@ -2656,7 +2661,7 @@ void spi_unregister_controller(struct spi_controller *ctlr)
 
 	/* Prevent addition of new devices, unregister existing ones */
 	if (IS_ENABLED(CONFIG_SPI_DYNAMIC))
-		mutex_lock(&ctlr->add_lock);
+		mutex_lock(&spi_add_lock);
 
 	device_for_each_child(&ctlr->dev, NULL, __unregister);
 

diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h
@@ -480,9 +480,6 @@ struct spi_controller {
 	/* I/O mutex */
 	struct mutex		io_mutex;
 
-	/* Used to avoid adding the same CS twice */
-	struct mutex		add_lock;
-
 	/* lock and mutex for SPI bus locking */
 	spinlock_t		bus_lock_spinlock;
 	struct mutex		bus_lock_mutex;