From 9688ed2ea8d6f7621ba66393cdf5e7e9d7e20457 Mon Sep 17 00:00:00 2001 From: Greg Kroah-Hartman Date: Thu, 21 Nov 2024 22:00:31 +0000 Subject: [PATCH] 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 --- drivers/spi/spi.c | 13 +++++++++---- include/linux/spi/spi.h | 3 --- 2 files changed, 9 insertions(+), 7 deletions(-) diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c index d03cbe5ce044..bb0cc9538aec 100644 --- 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 index 8af03d65d07a..e70ddc6d2a1e 100644 --- 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;