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 --- lib/clz_ctz.c | 43 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 43 insertions(+) create mode 100644 lib/clz_ctz.c (limited to 'lib/clz_ctz.c') diff --git a/lib/clz_ctz.c b/lib/clz_ctz.c new file mode 100644 index 000000000..8778ec44b --- /dev/null +++ b/lib/clz_ctz.c @@ -0,0 +1,43 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * lib/clz_ctz.c + * + * Copyright (C) 2013 Chanho Min + * + * The functions in this file aren't called directly, but are required by + * GCC builtins such as __builtin_ctz, and therefore they can't be removed + * despite appearing unreferenced in kernel source. + * + * __c[lt]z[sd]i2 can be overridden by linking arch-specific versions. + */ + +#include +#include + +int __weak __ctzsi2(int val); +int __weak __attribute_const__ __ctzsi2(int val) +{ + return __ffs(val); +} +EXPORT_SYMBOL(__ctzsi2); + +int __weak __clzsi2(int val); +int __weak __attribute_const__ __clzsi2(int val) +{ + return 32 - fls(val); +} +EXPORT_SYMBOL(__clzsi2); + +int __weak __clzdi2(u64 val); +int __weak __attribute_const__ __clzdi2(u64 val) +{ + return 64 - fls64(val); +} +EXPORT_SYMBOL(__clzdi2); + +int __weak __ctzdi2(u64 val); +int __weak __attribute_const__ __ctzdi2(u64 val) +{ + return __ffs64(val); +} +EXPORT_SYMBOL(__ctzdi2); -- cgit v1.3.1