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 --- tools/perf/util/mutex.c | 125 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 125 insertions(+) create mode 100644 tools/perf/util/mutex.c (limited to 'tools/perf/util/mutex.c') diff --git a/tools/perf/util/mutex.c b/tools/perf/util/mutex.c new file mode 100644 index 000000000..7aa1f3f55 --- /dev/null +++ b/tools/perf/util/mutex.c @@ -0,0 +1,125 @@ +// SPDX-License-Identifier: GPL-2.0 +#include "mutex.h" + +#include "debug.h" +#include +#include + +static void check_err(const char *fn, int err) +{ + char sbuf[STRERR_BUFSIZE]; + + if (err == 0) + return; + + pr_err("%s error: '%s'\n", fn, str_error_r(err, sbuf, sizeof(sbuf))); +} + +#define CHECK_ERR(err) check_err(__func__, err) + +static void __mutex_init(struct mutex *mtx, bool pshared, bool recursive) +{ + pthread_mutexattr_t attr; + + CHECK_ERR(pthread_mutexattr_init(&attr)); + +#ifndef NDEBUG + /* In normal builds enable error checking, such as recursive usage. */ + CHECK_ERR(pthread_mutexattr_settype(&attr, PTHREAD_MUTEX_ERRORCHECK)); +#endif + if (recursive) + CHECK_ERR(pthread_mutexattr_settype(&attr, PTHREAD_MUTEX_RECURSIVE)); + if (pshared) + CHECK_ERR(pthread_mutexattr_setpshared(&attr, PTHREAD_PROCESS_SHARED)); + CHECK_ERR(pthread_mutex_init(&mtx->lock, &attr)); + CHECK_ERR(pthread_mutexattr_destroy(&attr)); +} + +void mutex_init(struct mutex *mtx) +{ + __mutex_init(mtx, /*pshared=*/false, /*recursive=*/false); +} + +void mutex_init_pshared(struct mutex *mtx) +{ + __mutex_init(mtx, /*pshared=*/true, /*recursive=*/false); +} + +void mutex_init_recursive(struct mutex *mtx) +{ + __mutex_init(mtx, /*pshared=*/false, /*recursive=*/true); +} + +void mutex_destroy(struct mutex *mtx) +{ + CHECK_ERR(pthread_mutex_destroy(&mtx->lock)); +} + +void mutex_lock(struct mutex *mtx) + NO_THREAD_SAFETY_ANALYSIS +{ + CHECK_ERR(pthread_mutex_lock(&mtx->lock)); +} + +void mutex_unlock(struct mutex *mtx) + NO_THREAD_SAFETY_ANALYSIS +{ + CHECK_ERR(pthread_mutex_unlock(&mtx->lock)); +} + +bool mutex_trylock(struct mutex *mtx) +{ + int ret = pthread_mutex_trylock(&mtx->lock); + + if (ret == 0) + return true; /* Lock acquired. */ + + if (ret == EBUSY) + return false; /* Lock busy. */ + + /* Print error. */ + CHECK_ERR(ret); + return false; +} + +static void __cond_init(struct cond *cnd, bool pshared) +{ + pthread_condattr_t attr; + + CHECK_ERR(pthread_condattr_init(&attr)); + if (pshared) + CHECK_ERR(pthread_condattr_setpshared(&attr, PTHREAD_PROCESS_SHARED)); + + CHECK_ERR(pthread_cond_init(&cnd->cond, &attr)); + CHECK_ERR(pthread_condattr_destroy(&attr)); +} + +void cond_init(struct cond *cnd) +{ + __cond_init(cnd, /*pshared=*/false); +} + +void cond_init_pshared(struct cond *cnd) +{ + __cond_init(cnd, /*pshared=*/true); +} + +void cond_destroy(struct cond *cnd) +{ + CHECK_ERR(pthread_cond_destroy(&cnd->cond)); +} + +void cond_wait(struct cond *cnd, struct mutex *mtx) +{ + CHECK_ERR(pthread_cond_wait(&cnd->cond, &mtx->lock)); +} + +void cond_signal(struct cond *cnd) +{ + CHECK_ERR(pthread_cond_signal(&cnd->cond)); +} + +void cond_broadcast(struct cond *cnd) +{ + CHECK_ERR(pthread_cond_broadcast(&cnd->cond)); +} -- cgit v1.3.1