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/most/most_cdev.c | 546 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 546 insertions(+) create mode 100644 drivers/most/most_cdev.c (limited to 'drivers/most/most_cdev.c') diff --git a/drivers/most/most_cdev.c b/drivers/most/most_cdev.c new file mode 100644 index 000000000..5df508d8d --- /dev/null +++ b/drivers/most/most_cdev.c @@ -0,0 +1,546 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * cdev.c - Character device component for Mostcore + * + * Copyright (C) 2013-2015 Microchip Technology Germany II GmbH & Co. KG + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#define CHRDEV_REGION_SIZE 50 + +static const struct class most_cdev_class = { + .name = "most_cdev" +}; + +static struct cdev_component { + dev_t devno; + struct ida minor_id; + unsigned int major; + struct most_component cc; +} comp; + +struct comp_channel { + wait_queue_head_t wq; + spinlock_t unlink; /* synchronization lock to unlink channels */ + struct cdev cdev; + struct device *dev; + struct mutex io_mutex; + struct most_interface *iface; + struct most_channel_config *cfg; + unsigned int channel_id; + dev_t devno; + size_t mbo_offs; + DECLARE_KFIFO_PTR(fifo, typeof(struct mbo *)); + int access_ref; + struct list_head list; +}; + +#define to_channel(d) container_of(d, struct comp_channel, cdev) +static LIST_HEAD(channel_list); +static DEFINE_SPINLOCK(ch_list_lock); + +static inline bool ch_has_mbo(struct comp_channel *c) +{ + return channel_has_mbo(c->iface, c->channel_id, &comp.cc) > 0; +} + +static inline struct mbo *ch_get_mbo(struct comp_channel *c, struct mbo **mbo) +{ + if (!kfifo_peek(&c->fifo, mbo)) { + *mbo = most_get_mbo(c->iface, c->channel_id, &comp.cc); + if (*mbo) + kfifo_in(&c->fifo, mbo, 1); + } + return *mbo; +} + +static struct comp_channel *get_channel(struct most_interface *iface, int id) +{ + struct comp_channel *c, *tmp; + unsigned long flags; + + spin_lock_irqsave(&ch_list_lock, flags); + list_for_each_entry_safe(c, tmp, &channel_list, list) { + if ((c->iface == iface) && (c->channel_id == id)) { + spin_unlock_irqrestore(&ch_list_lock, flags); + return c; + } + } + spin_unlock_irqrestore(&ch_list_lock, flags); + return NULL; +} + +static void stop_channel(struct comp_channel *c) +{ + struct mbo *mbo; + + while (kfifo_out((struct kfifo *)&c->fifo, &mbo, 1)) + most_put_mbo(mbo); + most_stop_channel(c->iface, c->channel_id, &comp.cc); +} + +static void destroy_cdev(struct comp_channel *c) +{ + unsigned long flags; + + device_destroy(&most_cdev_class, c->devno); + cdev_del(&c->cdev); + spin_lock_irqsave(&ch_list_lock, flags); + list_del(&c->list); + spin_unlock_irqrestore(&ch_list_lock, flags); +} + +static void destroy_channel(struct comp_channel *c) +{ + ida_free(&comp.minor_id, MINOR(c->devno)); + kfifo_free(&c->fifo); + kfree(c); +} + +/** + * comp_open - implements the syscall to open the device + * @inode: inode pointer + * @filp: file pointer + * + * This stores the channel pointer in the private data field of + * the file structure and activates the channel within the core. + */ +static int comp_open(struct inode *inode, struct file *filp) +{ + struct comp_channel *c; + int ret; + + c = to_channel(inode->i_cdev); + filp->private_data = c; + + if (((c->cfg->direction == MOST_CH_RX) && + ((filp->f_flags & O_ACCMODE) != O_RDONLY)) || + ((c->cfg->direction == MOST_CH_TX) && + ((filp->f_flags & O_ACCMODE) != O_WRONLY))) { + return -EACCES; + } + + mutex_lock(&c->io_mutex); + if (!c->dev) { + mutex_unlock(&c->io_mutex); + return -ENODEV; + } + + if (c->access_ref) { + mutex_unlock(&c->io_mutex); + return -EBUSY; + } + + c->mbo_offs = 0; + ret = most_start_channel(c->iface, c->channel_id, &comp.cc); + if (!ret) + c->access_ref = 1; + mutex_unlock(&c->io_mutex); + return ret; +} + +/** + * comp_close - implements the syscall to close the device + * @inode: inode pointer + * @filp: file pointer + * + * This stops the channel within the core. + */ +static int comp_close(struct inode *inode, struct file *filp) +{ + struct comp_channel *c = to_channel(inode->i_cdev); + + mutex_lock(&c->io_mutex); + spin_lock(&c->unlink); + c->access_ref = 0; + spin_unlock(&c->unlink); + if (c->dev) { + stop_channel(c); + mutex_unlock(&c->io_mutex); + } else { + mutex_unlock(&c->io_mutex); + destroy_channel(c); + } + return 0; +} + +/** + * comp_write - implements the syscall to write to the device + * @filp: file pointer + * @buf: pointer to user buffer + * @count: number of bytes to write + * @offset: offset from where to start writing + */ +static ssize_t comp_write(struct file *filp, const char __user *buf, + size_t count, loff_t *offset) +{ + int ret; + size_t to_copy, left; + struct mbo *mbo = NULL; + struct comp_channel *c = filp->private_data; + + mutex_lock(&c->io_mutex); + while (c->dev && !ch_get_mbo(c, &mbo)) { + mutex_unlock(&c->io_mutex); + + if ((filp->f_flags & O_NONBLOCK)) + return -EAGAIN; + if (wait_event_interruptible(c->wq, ch_has_mbo(c) || !c->dev)) + return -ERESTARTSYS; + mutex_lock(&c->io_mutex); + } + + if (unlikely(!c->dev)) { + ret = -ENODEV; + goto unlock; + } + + to_copy = min(count, c->cfg->buffer_size - c->mbo_offs); + left = copy_from_user(mbo->virt_address + c->mbo_offs, buf, to_copy); + if (left == to_copy) { + ret = -EFAULT; + goto unlock; + } + + c->mbo_offs += to_copy - left; + if (c->mbo_offs >= c->cfg->buffer_size || + c->cfg->data_type == MOST_CH_CONTROL || + c->cfg->data_type == MOST_CH_ASYNC) { + kfifo_skip(&c->fifo); + mbo->buffer_length = c->mbo_offs; + c->mbo_offs = 0; + most_submit_mbo(mbo); + } + + ret = to_copy - left; +unlock: + mutex_unlock(&c->io_mutex); + return ret; +} + +/** + * comp_read - implements the syscall to read from the device + * @filp: file pointer + * @buf: pointer to user buffer + * @count: number of bytes to read + * @offset: offset from where to start reading + */ +static ssize_t +comp_read(struct file *filp, char __user *buf, size_t count, loff_t *offset) +{ + size_t to_copy, not_copied, copied; + struct mbo *mbo = NULL; + struct comp_channel *c = filp->private_data; + + mutex_lock(&c->io_mutex); + while (c->dev && !kfifo_peek(&c->fifo, &mbo)) { + mutex_unlock(&c->io_mutex); + if (filp->f_flags & O_NONBLOCK) + return -EAGAIN; + if (wait_event_interruptible(c->wq, + (!kfifo_is_empty(&c->fifo) || + (!c->dev)))) + return -ERESTARTSYS; + mutex_lock(&c->io_mutex); + } + + /* make sure we don't submit to gone devices */ + if (unlikely(!c->dev)) { + mutex_unlock(&c->io_mutex); + return -ENODEV; + } + + to_copy = min_t(size_t, + count, + mbo->processed_length - c->mbo_offs); + + not_copied = copy_to_user(buf, + mbo->virt_address + c->mbo_offs, + to_copy); + + copied = to_copy - not_copied; + + c->mbo_offs += copied; + if (c->mbo_offs >= mbo->processed_length) { + kfifo_skip(&c->fifo); + most_put_mbo(mbo); + c->mbo_offs = 0; + } + mutex_unlock(&c->io_mutex); + return copied; +} + +static __poll_t comp_poll(struct file *filp, poll_table *wait) +{ + struct comp_channel *c = filp->private_data; + __poll_t mask = 0; + + poll_wait(filp, &c->wq, wait); + + mutex_lock(&c->io_mutex); + if (c->cfg->direction == MOST_CH_RX) { + if (!c->dev || !kfifo_is_empty(&c->fifo)) + mask |= EPOLLIN | EPOLLRDNORM; + } else { + if (!c->dev || !kfifo_is_empty(&c->fifo) || ch_has_mbo(c)) + mask |= EPOLLOUT | EPOLLWRNORM; + } + mutex_unlock(&c->io_mutex); + return mask; +} + +/* + * Initialization of struct file_operations + */ +static const struct file_operations channel_fops = { + .owner = THIS_MODULE, + .read = comp_read, + .write = comp_write, + .open = comp_open, + .release = comp_close, + .poll = comp_poll, +}; + +/** + * comp_disconnect_channel - disconnect a channel + * @iface: pointer to interface instance + * @channel_id: channel index + * + * This frees allocated memory and removes the cdev that represents this + * channel in user space. + */ +static int comp_disconnect_channel(struct most_interface *iface, int channel_id) +{ + struct comp_channel *c; + + c = get_channel(iface, channel_id); + if (!c) + return -EINVAL; + + mutex_lock(&c->io_mutex); + spin_lock(&c->unlink); + c->dev = NULL; + spin_unlock(&c->unlink); + destroy_cdev(c); + if (c->access_ref) { + stop_channel(c); + wake_up_interruptible(&c->wq); + mutex_unlock(&c->io_mutex); + } else { + mutex_unlock(&c->io_mutex); + destroy_channel(c); + } + return 0; +} + +/** + * comp_rx_completion - completion handler for rx channels + * @mbo: pointer to buffer object that has completed + * + * This searches for the channel linked to this MBO and stores it in the local + * fifo buffer. + */ +static int comp_rx_completion(struct mbo *mbo) +{ + struct comp_channel *c; + + if (!mbo) + return -EINVAL; + + c = get_channel(mbo->ifp, mbo->hdm_channel_id); + if (!c) + return -EINVAL; + + spin_lock(&c->unlink); + if (!c->access_ref || !c->dev) { + spin_unlock(&c->unlink); + return -ENODEV; + } + kfifo_in(&c->fifo, &mbo, 1); + spin_unlock(&c->unlink); +#ifdef DEBUG_MESG + if (kfifo_is_full(&c->fifo)) + dev_warn(c->dev, "Fifo is full\n"); +#endif + wake_up_interruptible(&c->wq); + return 0; +} + +/** + * comp_tx_completion - completion handler for tx channels + * @iface: pointer to interface instance + * @channel_id: channel index/ID + * + * This wakes sleeping processes in the wait-queue. + */ +static int comp_tx_completion(struct most_interface *iface, int channel_id) +{ + struct comp_channel *c; + + c = get_channel(iface, channel_id); + if (!c) + return -EINVAL; + + if ((channel_id < 0) || (channel_id >= iface->num_channels)) { + dev_warn(c->dev, "Channel ID out of range\n"); + return -EINVAL; + } + + wake_up_interruptible(&c->wq); + return 0; +} + +/** + * comp_probe - probe function of the driver module + * @iface: pointer to interface instance + * @channel_id: channel index/ID + * @cfg: pointer to actual channel configuration + * @name: name of the device to be created + * @args: pointer to array of component parameters (from configfs) + * + * This allocates a channel object and creates the device node in /dev + * + * Returns 0 on success or error code otherwise. + */ +static int comp_probe(struct most_interface *iface, int channel_id, + struct most_channel_config *cfg, char *name, char *args) +{ + struct comp_channel *c; + unsigned long cl_flags; + int retval; + int current_minor; + + if (!cfg || !name) + return -EINVAL; + + c = get_channel(iface, channel_id); + if (c) + return -EEXIST; + + current_minor = ida_alloc(&comp.minor_id, GFP_KERNEL); + if (current_minor < 0) + return current_minor; + + c = kzalloc_obj(*c); + if (!c) { + retval = -ENOMEM; + goto err_remove_ida; + } + + c->devno = MKDEV(comp.major, current_minor); + cdev_init(&c->cdev, &channel_fops); + c->cdev.owner = THIS_MODULE; + retval = cdev_add(&c->cdev, c->devno, 1); + if (retval < 0) + goto err_free_c; + c->iface = iface; + c->cfg = cfg; + c->channel_id = channel_id; + c->access_ref = 0; + spin_lock_init(&c->unlink); + INIT_KFIFO(c->fifo); + retval = kfifo_alloc(&c->fifo, cfg->num_buffers, GFP_KERNEL); + if (retval) + goto err_del_cdev_and_free_channel; + init_waitqueue_head(&c->wq); + mutex_init(&c->io_mutex); + spin_lock_irqsave(&ch_list_lock, cl_flags); + list_add_tail(&c->list, &channel_list); + spin_unlock_irqrestore(&ch_list_lock, cl_flags); + c->dev = device_create(&most_cdev_class, NULL, c->devno, NULL, "%s", name); + + if (IS_ERR(c->dev)) { + retval = PTR_ERR(c->dev); + goto err_free_kfifo_and_del_list; + } + kobject_uevent(&c->dev->kobj, KOBJ_ADD); + return 0; + +err_free_kfifo_and_del_list: + kfifo_free(&c->fifo); + list_del(&c->list); +err_del_cdev_and_free_channel: + cdev_del(&c->cdev); +err_free_c: + kfree(c); +err_remove_ida: + ida_free(&comp.minor_id, current_minor); + return retval; +} + +static struct cdev_component comp = { + .cc = { + .mod = THIS_MODULE, + .name = "cdev", + .probe_channel = comp_probe, + .disconnect_channel = comp_disconnect_channel, + .rx_completion = comp_rx_completion, + .tx_completion = comp_tx_completion, + }, +}; + + +static int __init most_cdev_init(void) +{ + int err; + + err = class_register(&most_cdev_class); + if (err) + return err; + + ida_init(&comp.minor_id); + + err = alloc_chrdev_region(&comp.devno, 0, CHRDEV_REGION_SIZE, "cdev"); + if (err < 0) + goto dest_ida; + comp.major = MAJOR(comp.devno); + err = most_register_component(&comp.cc); + if (err) + goto free_cdev; + err = most_register_configfs_subsys(&comp.cc); + if (err) + goto deregister_comp; + return 0; + +deregister_comp: + most_deregister_component(&comp.cc); +free_cdev: + unregister_chrdev_region(comp.devno, CHRDEV_REGION_SIZE); +dest_ida: + ida_destroy(&comp.minor_id); + class_unregister(&most_cdev_class); + return err; +} + +static void __exit most_cdev_exit(void) +{ + struct comp_channel *c, *tmp; + + most_deregister_configfs_subsys(&comp.cc); + most_deregister_component(&comp.cc); + + list_for_each_entry_safe(c, tmp, &channel_list, list) { + destroy_cdev(c); + destroy_channel(c); + } + unregister_chrdev_region(comp.devno, CHRDEV_REGION_SIZE); + ida_destroy(&comp.minor_id); + class_unregister(&most_cdev_class); +} + +module_init(most_cdev_init); +module_exit(most_cdev_exit); +MODULE_AUTHOR("Christian Gromm "); +MODULE_LICENSE("GPL"); +MODULE_DESCRIPTION("character device component for mostcore"); -- cgit v1.3.1