diff options
Diffstat (limited to 'samples/hung_task')
| -rw-r--r-- | samples/hung_task/hung_task_tests.c | 81 |
1 files changed, 74 insertions, 7 deletions
diff --git a/samples/hung_task/hung_task_tests.c b/samples/hung_task/hung_task_tests.c index a5c09bd3a47d..0360ec916890 100644 --- a/samples/hung_task/hung_task_tests.c +++ b/samples/hung_task/hung_task_tests.c @@ -4,11 +4,12 @@ * semaphore, etc. * * Usage: Load this module and read `<debugfs>/hung_task/mutex`, - * `<debugfs>/hung_task/semaphore`, etc., with 2 or more processes. + * `<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, etc.). Note that this may freeze - * your system or cause a panic. Use only for testing purposes. + * 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> @@ -17,21 +18,29 @@ #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 SLEEP_SECOND 256 +#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); @@ -46,6 +55,10 @@ static ssize_t read_dummy_mutex(struct file *file, char __user *user_buf, 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); @@ -58,6 +71,46 @@ static ssize_t read_dummy_semaphore(struct file *file, char __user *user_buf, 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, @@ -68,6 +121,16 @@ 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); @@ -79,6 +142,10 @@ static int __init hung_task_tests_init(void) &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; } |