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 --- net/ceph/string_table.c | 106 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 106 insertions(+) create mode 100644 net/ceph/string_table.c (limited to 'net/ceph/string_table.c') diff --git a/net/ceph/string_table.c b/net/ceph/string_table.c new file mode 100644 index 000000000..3191d9d16 --- /dev/null +++ b/net/ceph/string_table.c @@ -0,0 +1,106 @@ +// SPDX-License-Identifier: GPL-2.0 +#include +#include +#include +#include +#include + +static DEFINE_SPINLOCK(string_tree_lock); +static struct rb_root string_tree = RB_ROOT; + +struct ceph_string *ceph_find_or_create_string(const char* str, size_t len) +{ + struct ceph_string *cs, *exist; + struct rb_node **p, *parent; + int ret; + + exist = NULL; + spin_lock(&string_tree_lock); + p = &string_tree.rb_node; + while (*p) { + exist = rb_entry(*p, struct ceph_string, node); + ret = ceph_compare_string(exist, str, len); + if (ret > 0) + p = &(*p)->rb_left; + else if (ret < 0) + p = &(*p)->rb_right; + else + break; + exist = NULL; + } + if (exist && !kref_get_unless_zero(&exist->kref)) { + rb_erase(&exist->node, &string_tree); + RB_CLEAR_NODE(&exist->node); + exist = NULL; + } + spin_unlock(&string_tree_lock); + if (exist) + return exist; + + cs = kmalloc(sizeof(*cs) + len + 1, GFP_NOFS); + if (!cs) + return NULL; + + kref_init(&cs->kref); + cs->len = len; + memcpy(cs->str, str, len); + cs->str[len] = 0; + +retry: + exist = NULL; + parent = NULL; + p = &string_tree.rb_node; + spin_lock(&string_tree_lock); + while (*p) { + parent = *p; + exist = rb_entry(*p, struct ceph_string, node); + ret = ceph_compare_string(exist, str, len); + if (ret > 0) + p = &(*p)->rb_left; + else if (ret < 0) + p = &(*p)->rb_right; + else + break; + exist = NULL; + } + ret = 0; + if (!exist) { + rb_link_node(&cs->node, parent, p); + rb_insert_color(&cs->node, &string_tree); + } else if (!kref_get_unless_zero(&exist->kref)) { + rb_erase(&exist->node, &string_tree); + RB_CLEAR_NODE(&exist->node); + ret = -EAGAIN; + } + spin_unlock(&string_tree_lock); + if (ret == -EAGAIN) + goto retry; + + if (exist) { + kfree(cs); + cs = exist; + } + + return cs; +} +EXPORT_SYMBOL(ceph_find_or_create_string); + +void ceph_release_string(struct kref *ref) +{ + struct ceph_string *cs = container_of(ref, struct ceph_string, kref); + + spin_lock(&string_tree_lock); + if (!RB_EMPTY_NODE(&cs->node)) { + rb_erase(&cs->node, &string_tree); + RB_CLEAR_NODE(&cs->node); + } + spin_unlock(&string_tree_lock); + + kfree_rcu(cs, rcu); +} +EXPORT_SYMBOL(ceph_release_string); + +bool ceph_strings_empty(void) +{ + return RB_EMPTY_ROOT(&string_tree); +} -- cgit v1.3.1