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authorLinus Torvalds <torvalds@linux-foundation.org>2026-08-24 08:46:03 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2026-08-24 08:46:03 -0700
commitcf9610f9116d55c5a66ef9f1faecacabd93a9322 (patch)
tree757a3d280760c654767631cab5ad8af2d86d1848 /samples/hung_task
downloadlinux-stable-cf9610f9116d55c5a66ef9f1faecacabd93a9322.tar.gz
linux-stable-cf9610f9116d55c5a66ef9f1faecacabd93a9322.zip
Merge tag 'pinctrl-v7.3-1' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-pinctrlgrafted
Pull pin control updates from Linus Walleij: "Core changes: - Use the non-blocking mux_state_try_select() in the generic MUX pin control back-end - Free pin maps on pinctrl_generic_to_map() failure in the core helpers New hardware pin control: - Qualcomm Maili TLMM SoC, PMG1110 PMIC, and Eliza LPASS LPI TLMM SoC (this is for the low power audio, LPASS = Low Power Audio SubSystem portions) - Upboard support on top of the Intel pin controller - Apple T6030 and T6031 support (just compatible strings) - Samsung Exynos 8855 SoC - Mediatek MT6858 SoC - Rockchip RK3308B and RV1106 SoCs - Airoha EN7523 and AN7563 SoCs Improvements: - Qualcomm TLMM GPIOs are unconditionally marked as wakeup capable - Qualcomm improvements on top of the Qualcomm PDC (power domain controller) irqchip improvements from tglx:s tree - Qualcomm IPQ806x and IPQ9650 non-urgent pin grop fixups - The NPCM8xx driver has been put into shape fixing many pin and group definitions - Some non-urgent Tegra 264 pin assignments are fixed up - Some non-urgent fixups to Airoha AN7581 and AN7583 registers and pin assignments, missing features etc" * tag 'pinctrl-v7.3-1' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-pinctrl: (130 commits) dt-bindings: pinctrl: Convert TI DA850 pupd to DT schema pinctrl: meson: sync some modify from A4 pinctrl: meson: a4: Add input enable pin configuration pinctrl: realtek: rtd1625: remove unused group name spdif_sel pinctrl: realtek: rtd1625: fix base_bit for VE4 GPIO 13 dt-bindings: pinctrl: microchip,pic32mzda-pinctrl: Convert to DT schema Revert "Merge branch 'ib-rsk7204' into devel" pinctrl: rockchip: Add RV1106 pinctrl support dt-bindings: pinctrl: rockchip: Add RV1106 compatible pinctrl: rockchip: Decode drive strength in the get function pinctrl: fix PINCTRL_GENERIC_MUX not always being selectable pinctrl: airoha: add support of an7563 SoC dt-bindings: pinctrl: airoha: add support of an7563 pin controller pinctrl: airoha: try to find chip scu node by phandle first pinctrl: airoha: add support of en7523 SoC dt-bindings: pinctrl: airoha: add support of en7523 pin controller pinctrl: airoha: an7583: add support for olt pinmux pinctrl: airoha: an7583: add support for pon_alt pinmux pinctrl: airoha: an7583: add support for npu_uart pinmux dt-bindings: pinctrl: airoha: an7583: add missed features ...
Diffstat (limited to 'samples/hung_task')
-rw-r--r--samples/hung_task/Makefile2
-rw-r--r--samples/hung_task/hung_task_tests.c164
2 files changed, 166 insertions, 0 deletions
diff --git a/samples/hung_task/Makefile b/samples/hung_task/Makefile
new file mode 100644
index 000000000..86036f1a2
--- /dev/null
+++ b/samples/hung_task/Makefile
@@ -0,0 +1,2 @@
+# SPDX-License-Identifier: GPL-2.0-only
+obj-$(CONFIG_SAMPLE_HUNG_TASK) += hung_task_tests.o
diff --git a/samples/hung_task/hung_task_tests.c b/samples/hung_task/hung_task_tests.c
new file mode 100644
index 000000000..0360ec916
--- /dev/null
+++ b/samples/hung_task/hung_task_tests.c
@@ -0,0 +1,164 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * hung_task_tests.c - Sample code for testing hung tasks with mutex,
+ * semaphore, etc.
+ *
+ * Usage: Load this module and read `<debugfs>/hung_task/mutex`,
+ * `<debugfs>/hung_task/semaphore`, `<debugfs>/hung_task/rw_semaphore_read`,
+ * `<debugfs>/hung_task/rw_semaphore_write`, etc., with 2 or more processes.
+ *
+ * This is for testing kernel hung_task error messages with various locking
+ * mechanisms (e.g., mutex, semaphore, rw_semaphore_read, rw_semaphore_write, etc.).
+ * Note that this may freeze your system or cause a panic. Use only for testing purposes.
+ */
+
+#include <linux/debugfs.h>
+#include <linux/delay.h>
+#include <linux/fs.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/semaphore.h>
+#include <linux/rwsem.h>
+
+#define HUNG_TASK_DIR "hung_task"
+#define HUNG_TASK_MUTEX_FILE "mutex"
+#define HUNG_TASK_SEM_FILE "semaphore"
+#define HUNG_TASK_RWSEM_READ_FILE "rw_semaphore_read"
+#define HUNG_TASK_RWSEM_WRITE_FILE "rw_semaphore_write"
+#define SLEEP_SECOND 256
+
+static const char dummy_string[] = "This is a dummy string.";
+static DEFINE_MUTEX(dummy_mutex);
+static DEFINE_SEMAPHORE(dummy_sem, 1);
+static DECLARE_RWSEM(dummy_rwsem);
+static struct dentry *hung_task_dir;
+
+/* Mutex-based read function */
+static ssize_t read_dummy_mutex(struct file *file, char __user *user_buf,
+ size_t count, loff_t *ppos)
+{
+ /* Check if data is already read */
+ if (*ppos >= sizeof(dummy_string))
+ return 0;
+
+ /* Second task waits on mutex, entering uninterruptible sleep */
+ guard(mutex)(&dummy_mutex);
+
+ /* First task sleeps here, interruptible */
+ msleep_interruptible(SLEEP_SECOND * 1000);
+
+ return simple_read_from_buffer(user_buf, count, ppos, dummy_string,
+ sizeof(dummy_string));
+}
+
+/* Semaphore-based read function */
+static ssize_t read_dummy_semaphore(struct file *file, char __user *user_buf,
+ size_t count, loff_t *ppos)
+{
+ /* Check if data is already read */
+ if (*ppos >= sizeof(dummy_string))
+ return 0;
+
+ /* Second task waits on semaphore, entering uninterruptible sleep */
+ down(&dummy_sem);
+
+ /* First task sleeps here, interruptible */
+ msleep_interruptible(SLEEP_SECOND * 1000);
+
+ up(&dummy_sem);
+
+ return simple_read_from_buffer(user_buf, count, ppos, dummy_string,
+ sizeof(dummy_string));
+}
+
+/* Read-write semaphore read function */
+static ssize_t read_dummy_rwsem_read(struct file *file, char __user *user_buf,
+ size_t count, loff_t *ppos)
+{
+ /* Check if data is already read */
+ if (*ppos >= sizeof(dummy_string))
+ return 0;
+
+ /* Acquires read lock, allowing concurrent readers but blocks if write lock is held */
+ down_read(&dummy_rwsem);
+
+ /* Sleeps here, potentially triggering hung task detection if lock is held too long */
+ msleep_interruptible(SLEEP_SECOND * 1000);
+
+ up_read(&dummy_rwsem);
+
+ return simple_read_from_buffer(user_buf, count, ppos, dummy_string,
+ sizeof(dummy_string));
+}
+
+/* Read-write semaphore write function */
+static ssize_t read_dummy_rwsem_write(struct file *file, char __user *user_buf,
+ size_t count, loff_t *ppos)
+{
+ /* Check if data is already read */
+ if (*ppos >= sizeof(dummy_string))
+ return 0;
+
+ /* Acquires exclusive write lock, blocking all other readers and writers */
+ down_write(&dummy_rwsem);
+
+ /* Sleeps here, potentially triggering hung task detection if lock is held too long */
+ msleep_interruptible(SLEEP_SECOND * 1000);
+
+ up_write(&dummy_rwsem);
+
+ return simple_read_from_buffer(user_buf, count, ppos, dummy_string,
+ sizeof(dummy_string));
+}
+
+/* File operations for mutex */
+static const struct file_operations hung_task_mutex_fops = {
+ .read = read_dummy_mutex,
+};
+
+/* File operations for semaphore */
+static const struct file_operations hung_task_sem_fops = {
+ .read = read_dummy_semaphore,
+};
+
+/* File operations for rw_semaphore read */
+static const struct file_operations hung_task_rwsem_read_fops = {
+ .read = read_dummy_rwsem_read,
+};
+
+/* File operations for rw_semaphore write */
+static const struct file_operations hung_task_rwsem_write_fops = {
+ .read = read_dummy_rwsem_write,
+};
+
+static int __init hung_task_tests_init(void)
+{
+ hung_task_dir = debugfs_create_dir(HUNG_TASK_DIR, NULL);
+ if (IS_ERR(hung_task_dir))
+ return PTR_ERR(hung_task_dir);
+
+ /* Create debugfs files for mutex and semaphore tests */
+ debugfs_create_file(HUNG_TASK_MUTEX_FILE, 0400, hung_task_dir, NULL,
+ &hung_task_mutex_fops);
+ debugfs_create_file(HUNG_TASK_SEM_FILE, 0400, hung_task_dir, NULL,
+ &hung_task_sem_fops);
+ debugfs_create_file(HUNG_TASK_RWSEM_READ_FILE, 0400, hung_task_dir, NULL,
+ &hung_task_rwsem_read_fops);
+ debugfs_create_file(HUNG_TASK_RWSEM_WRITE_FILE, 0400, hung_task_dir, NULL,
+ &hung_task_rwsem_write_fops);
+
+ return 0;
+}
+
+static void __exit hung_task_tests_exit(void)
+{
+ debugfs_remove_recursive(hung_task_dir);
+}
+
+module_init(hung_task_tests_init);
+module_exit(hung_task_tests_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Masami Hiramatsu <mhiramat@kernel.org>");
+MODULE_AUTHOR("Zi Li <amaindex@outlook.com>");
+MODULE_DESCRIPTION("Simple sleep under lock files for testing hung task");