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 --- fs/lockd/procfs.c | 92 +++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 92 insertions(+) create mode 100644 fs/lockd/procfs.c (limited to 'fs/lockd/procfs.c') diff --git a/fs/lockd/procfs.c b/fs/lockd/procfs.c new file mode 100644 index 000000000..a01f08c8c --- /dev/null +++ b/fs/lockd/procfs.c @@ -0,0 +1,92 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Procfs support for lockd + * + * Copyright (c) 2014 Jeff Layton + */ + +#include +#include +#include +#include +#include + +#include "netns.h" +#include "procfs.h" + +/* + * We only allow strings that start with 'Y', 'y', or '1'. + */ +static ssize_t +nlm_end_grace_write(struct file *file, const char __user *buf, size_t size, + loff_t *pos) +{ + char *data; + struct lockd_net *ln = net_generic(current->nsproxy->net_ns, + lockd_net_id); + + if (size < 1) + return -EINVAL; + + data = simple_transaction_get(file, buf, size); + if (IS_ERR(data)) + return PTR_ERR(data); + + switch(data[0]) { + case 'Y': + case 'y': + case '1': + locks_end_grace(&ln->lockd_manager); + break; + default: + return -EINVAL; + } + + return size; +} + +static ssize_t +nlm_end_grace_read(struct file *file, char __user *buf, size_t size, + loff_t *pos) +{ + struct lockd_net *ln = net_generic(current->nsproxy->net_ns, + lockd_net_id); + char resp[3]; + + resp[0] = list_empty(&ln->lockd_manager.list) ? 'Y' : 'N'; + resp[1] = '\n'; + resp[2] = '\0'; + + return simple_read_from_buffer(buf, size, pos, resp, sizeof(resp)); +} + +static const struct proc_ops lockd_end_grace_proc_ops = { + .proc_write = nlm_end_grace_write, + .proc_read = nlm_end_grace_read, + .proc_lseek = default_llseek, + .proc_release = simple_transaction_release, +}; + +int __init +lockd_create_procfs(void) +{ + struct proc_dir_entry *entry; + + entry = proc_mkdir("fs/lockd", NULL); + if (!entry) + return -ENOMEM; + entry = proc_create("nlm_end_grace", S_IRUGO|S_IWUSR, entry, + &lockd_end_grace_proc_ops); + if (!entry) { + remove_proc_entry("fs/lockd", NULL); + return -ENOMEM; + } + return 0; +} + +void __exit +lockd_remove_procfs(void) +{ + remove_proc_entry("fs/lockd/nlm_end_grace", NULL); + remove_proc_entry("fs/lockd", NULL); +} -- cgit v1.3.1