From 4617721c502b2ddaa4e324e86da4997edf738fa5 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Wed, 2 Sep 2026 09:55:01 -0400 Subject: ftrace: Synchronize the initialization of ftrace_ops There's some internal state that ftrace_ops needs to have set, but since it can be declared outside of the ftrace.c code, it calls ftrace_ops_init() on the ops in every global function. The issue is that if two tasks call it on the same ops at the same time it is possible to have the initialization of one corrupt the initialization of the other call. Create a ops_mutex to use to synchronize every initialization of the ftrace_ops. The mutex is taken within checking the ftrace_ops flag that states it was initializied but the flag is checked again after the mutex has been taken. Checking first outside the mutex allows it to shortcut having to take the mutex. But then the check needs to be done again after the mute is taken in case of races. Cc: stable@vger.kernel.org Link: https://patch.msgid.link/20260902095501.6b59af20@gandalf.local.home Fixes: f04f24fb7e48d ("ftrace, kprobes: Fix a deadlock on ftrace_regex_lock") Reported-by: sashiko-bot@kernel.org Close: https://lore.kernel.org/all/20260829025528.49A831F000E9@smtp.kernel.org/ Signed-off-by: Steven Rostedt --- drivers/accel/drm_accel.c | 208 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 208 insertions(+) create mode 100644 drivers/accel/drm_accel.c (limited to 'drivers/accel/drm_accel.c') diff --git a/drivers/accel/drm_accel.c b/drivers/accel/drm_accel.c new file mode 100644 index 000000000..ca3357acd --- /dev/null +++ b/drivers/accel/drm_accel.c @@ -0,0 +1,208 @@ +// SPDX-License-Identifier: GPL-2.0 + +/* + * Copyright 2022 HabanaLabs, Ltd. + * All Rights Reserved. + * + */ + +#include +#include +#include + +#include +#include +#include +#include +#include +#include +#include + +DEFINE_XARRAY_ALLOC(accel_minors_xa); + +static const struct device_type accel_sysfs_device_minor = { + .name = "accel_minor" +}; + +static char *accel_devnode(const struct device *dev, umode_t *mode) +{ + return kasprintf(GFP_KERNEL, "accel/%s", dev_name(dev)); +} + +static const struct class accel_class = { + .name = "accel", + .devnode = accel_devnode, +}; + +static int accel_sysfs_init(void) +{ + return class_register(&accel_class); +} + +static void accel_sysfs_destroy(void) +{ + class_unregister(&accel_class); +} + +static int accel_name_info(struct seq_file *m, void *data) +{ + struct drm_info_node *node = (struct drm_info_node *) m->private; + struct drm_minor *minor = node->minor; + struct drm_device *dev = minor->dev; + struct drm_master *master; + + mutex_lock(&dev->master_mutex); + master = dev->master; + seq_printf(m, "%s", dev->driver->name); + if (dev->dev) + seq_printf(m, " dev=%s", dev_name(dev->dev)); + if (master && master->unique) + seq_printf(m, " master=%s", master->unique); + if (dev->unique) + seq_printf(m, " unique=%s", dev->unique); + seq_puts(m, "\n"); + mutex_unlock(&dev->master_mutex); + + return 0; +} + +static const struct drm_info_list accel_debugfs_list[] = { + {"name", accel_name_info, 0} +}; +#define ACCEL_DEBUGFS_ENTRIES ARRAY_SIZE(accel_debugfs_list) + +/** + * accel_debugfs_register() - Register debugfs for device + * @dev: Pointer to the device instance. + * + * Creates common files for accelerators. + */ +void accel_debugfs_register(struct drm_device *dev) +{ + struct drm_minor *minor = dev->accel; + + minor->debugfs_root = dev->debugfs_root; + + drm_debugfs_create_files(accel_debugfs_list, ACCEL_DEBUGFS_ENTRIES, + dev->debugfs_root, minor); +} + +/** + * accel_set_device_instance_params() - Set some device parameters for accel device + * @kdev: Pointer to the device instance. + * @index: The minor's index + * + * This function creates the dev_t of the device using the accel major and + * the device's minor number. In addition, it sets the class and type of the + * device instance to the accel sysfs class and device type, respectively. + */ +void accel_set_device_instance_params(struct device *kdev, int index) +{ + kdev->devt = MKDEV(ACCEL_MAJOR, index); + kdev->class = &accel_class; + kdev->type = &accel_sysfs_device_minor; +} + +/** + * accel_open - open method for ACCEL file + * @inode: device inode + * @filp: file pointer. + * + * This function must be used by drivers as their &file_operations.open method. + * It looks up the correct ACCEL device and instantiates all the per-file + * resources for it. It also calls the &drm_driver.open driver callback. + * + * Return: 0 on success or negative errno value on failure. + */ +int accel_open(struct inode *inode, struct file *filp) +{ + struct drm_device *dev; + struct drm_minor *minor; + int retcode; + + minor = drm_minor_acquire(&accel_minors_xa, iminor(inode)); + if (IS_ERR(minor)) + return PTR_ERR(minor); + + dev = minor->dev; + + atomic_fetch_inc(&dev->open_count); + + /* share address_space across all char-devs of a single device */ + filp->f_mapping = dev->anon_inode->i_mapping; + + retcode = drm_open_helper(filp, minor); + if (retcode) + goto err_undo; + + return 0; + +err_undo: + atomic_dec(&dev->open_count); + drm_minor_release(minor); + return retcode; +} +EXPORT_SYMBOL_GPL(accel_open); + +static int accel_stub_open(struct inode *inode, struct file *filp) +{ + const struct file_operations *new_fops; + struct drm_minor *minor; + int err; + + minor = drm_minor_acquire(&accel_minors_xa, iminor(inode)); + if (IS_ERR(minor)) + return PTR_ERR(minor); + + new_fops = fops_get(minor->dev->driver->fops); + if (!new_fops) { + err = -ENODEV; + goto out; + } + + replace_fops(filp, new_fops); + if (filp->f_op->open) + err = filp->f_op->open(inode, filp); + else + err = 0; + +out: + drm_minor_release(minor); + + return err; +} + +static const struct file_operations accel_stub_fops = { + .owner = THIS_MODULE, + .open = accel_stub_open, + .llseek = noop_llseek, +}; + +void accel_core_exit(void) +{ + unregister_chrdev(ACCEL_MAJOR, "accel"); + accel_sysfs_destroy(); + WARN_ON(!xa_empty(&accel_minors_xa)); +} + +int __init accel_core_init(void) +{ + int ret; + + ret = accel_sysfs_init(); + if (ret < 0) { + DRM_ERROR("Cannot create ACCEL class: %d\n", ret); + goto error; + } + + ret = register_chrdev(ACCEL_MAJOR, "accel", &accel_stub_fops); + if (ret < 0) + DRM_ERROR("Cannot register ACCEL major: %d\n", ret); + +error: + /* + * Any cleanup due to errors will be done in drm_core_exit() that + * will call accel_core_exit() + */ + return ret; +} -- cgit v1.3.1