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/interconnect/debugfs-client.c | 183 ++++++++++++++++++++++++++++++++++ 1 file changed, 183 insertions(+) create mode 100644 drivers/interconnect/debugfs-client.c (limited to 'drivers/interconnect/debugfs-client.c') diff --git a/drivers/interconnect/debugfs-client.c b/drivers/interconnect/debugfs-client.c new file mode 100644 index 000000000..91f86d923 --- /dev/null +++ b/drivers/interconnect/debugfs-client.c @@ -0,0 +1,183 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright (c) 2023, Qualcomm Innovation Center, Inc. All rights reserved. + */ +#include +#include +#include + +#include "internal.h" + +/* + * This can be dangerous, therefore don't provide any real compile time + * configuration option for this feature. + * People who want to use this will need to modify the source code directly. + */ +#undef INTERCONNECT_ALLOW_WRITE_DEBUGFS + +#if defined(INTERCONNECT_ALLOW_WRITE_DEBUGFS) && defined(CONFIG_DEBUG_FS) + +static LIST_HEAD(debugfs_paths); +static DEFINE_MUTEX(debugfs_lock); + +static struct platform_device *pdev; +static struct icc_path *cur_path; + +static char *src_node; +static char *dst_node; +static u32 avg_bw; +static u32 peak_bw; +static u32 tag; + +struct debugfs_path { + const char *src; + const char *dst; + struct icc_path *path; + struct list_head list; +}; + +static struct icc_path *get_path(const char *src, const char *dst) +{ + struct debugfs_path *path; + + list_for_each_entry(path, &debugfs_paths, list) { + if (!strcmp(path->src, src) && !strcmp(path->dst, dst)) + return path->path; + } + + return NULL; +} + +static int icc_get_set(void *data, u64 val) +{ + struct debugfs_path *debugfs_path; + char *src, *dst; + int ret = 0; + + mutex_lock(&debugfs_lock); + + rcu_read_lock(); + src = rcu_dereference(src_node); + dst = rcu_dereference(dst_node); + + /* + * If we've already looked up a path, then use the existing one instead + * of calling icc_get() again. This allows for updating previous BW + * votes when "get" is written to multiple times for multiple paths. + */ + cur_path = get_path(src, dst); + if (cur_path) { + rcu_read_unlock(); + goto out; + } + + src = kstrdup(src, GFP_ATOMIC); + dst = kstrdup(dst, GFP_ATOMIC); + rcu_read_unlock(); + + if (!src || !dst) { + ret = -ENOMEM; + goto err_free; + } + + cur_path = icc_get(&pdev->dev, src, dst); + if (IS_ERR(cur_path)) { + ret = PTR_ERR(cur_path); + goto err_free; + } + + debugfs_path = kzalloc_obj(*debugfs_path); + if (!debugfs_path) { + ret = -ENOMEM; + goto err_put; + } + + debugfs_path->path = cur_path; + debugfs_path->src = src; + debugfs_path->dst = dst; + list_add_tail(&debugfs_path->list, &debugfs_paths); + + goto out; + +err_put: + icc_put(cur_path); +err_free: + kfree(src); + kfree(dst); +out: + mutex_unlock(&debugfs_lock); + return ret; +} + +DEFINE_DEBUGFS_ATTRIBUTE(icc_get_fops, NULL, icc_get_set, "%llu\n"); + +static int icc_commit_set(void *data, u64 val) +{ + int ret; + + mutex_lock(&debugfs_lock); + + if (!cur_path) { + ret = -EINVAL; + goto out; + } + + if (IS_ERR(cur_path)) { + ret = PTR_ERR(cur_path); + goto out; + } + + icc_set_tag(cur_path, tag); + ret = icc_set_bw(cur_path, avg_bw, peak_bw); +out: + mutex_unlock(&debugfs_lock); + return ret; +} + +DEFINE_DEBUGFS_ATTRIBUTE(icc_commit_fops, NULL, icc_commit_set, "%llu\n"); + +int icc_debugfs_client_init(struct dentry *icc_dir) +{ + struct dentry *client_dir; + int ret; + + pdev = platform_device_alloc("icc-debugfs-client", PLATFORM_DEVID_NONE); + if (!pdev) + return -ENOMEM; + + ret = platform_device_add(pdev); + if (ret) { + pr_err("%s: failed to add platform device: %d\n", __func__, ret); + platform_device_put(pdev); + return ret; + } + + src_node = kstrdup("", GFP_KERNEL); + dst_node = kstrdup("", GFP_KERNEL); + if (!src_node || !dst_node) { + kfree(dst_node); + kfree(src_node); + return -ENOMEM; + } + + client_dir = debugfs_create_dir("test_client", icc_dir); + + debugfs_create_str("src_node", 0600, client_dir, &src_node); + debugfs_create_str("dst_node", 0600, client_dir, &dst_node); + debugfs_create_file("get", 0200, client_dir, NULL, &icc_get_fops); + debugfs_create_u32("avg_bw", 0600, client_dir, &avg_bw); + debugfs_create_u32("peak_bw", 0600, client_dir, &peak_bw); + debugfs_create_u32("tag", 0600, client_dir, &tag); + debugfs_create_file("commit", 0200, client_dir, NULL, &icc_commit_fops); + + return 0; +} + +#else + +int icc_debugfs_client_init(struct dentry *icc_dir) +{ + return 0; +} + +#endif -- cgit v1.3.1