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/testing/selftests/kcmp/.gitignore | 3 + tools/testing/selftests/kcmp/Makefile | 9 ++ tools/testing/selftests/kcmp/kcmp_test.c | 168 +++++++++++++++++++++++++++++++ 3 files changed, 180 insertions(+) create mode 100644 tools/testing/selftests/kcmp/.gitignore create mode 100644 tools/testing/selftests/kcmp/Makefile create mode 100644 tools/testing/selftests/kcmp/kcmp_test.c (limited to 'tools/testing/selftests/kcmp') diff --git a/tools/testing/selftests/kcmp/.gitignore b/tools/testing/selftests/kcmp/.gitignore new file mode 100644 index 000000000..38ccdfe80 --- /dev/null +++ b/tools/testing/selftests/kcmp/.gitignore @@ -0,0 +1,3 @@ +# SPDX-License-Identifier: GPL-2.0-only +kcmp_test +kcmp-test-file diff --git a/tools/testing/selftests/kcmp/Makefile b/tools/testing/selftests/kcmp/Makefile new file mode 100644 index 000000000..59a1e5379 --- /dev/null +++ b/tools/testing/selftests/kcmp/Makefile @@ -0,0 +1,9 @@ +# SPDX-License-Identifier: GPL-2.0-only +CFLAGS += $(KHDR_INCLUDES) + +TEST_GEN_PROGS := kcmp_test + +EXTRA_CLEAN := $(OUTPUT)/kcmp-test-file + +include ../lib.mk + diff --git a/tools/testing/selftests/kcmp/kcmp_test.c b/tools/testing/selftests/kcmp/kcmp_test.c new file mode 100644 index 000000000..79aa438b7 --- /dev/null +++ b/tools/testing/selftests/kcmp/kcmp_test.c @@ -0,0 +1,168 @@ +// SPDX-License-Identifier: GPL-2.0 +#define _GNU_SOURCE + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include +#include +#include +#include +#include + +#include "kselftest.h" + +static long sys_kcmp(int pid1, int pid2, int type, unsigned long fd1, unsigned long fd2) +{ + return syscall(__NR_kcmp, pid1, pid2, type, fd1, fd2); +} + +static const unsigned int duped_num = 64; + +int main(int argc, char **argv) +{ + const char kpath[] = "kcmp-test-file"; + struct kcmp_epoll_slot epoll_slot; + struct epoll_event ev; + int pid1, pid2; + int pipefd[2]; + int fd1, fd2; + int epollfd; + int status; + int fddup; + + fd1 = open(kpath, O_RDWR | O_CREAT | O_TRUNC, 0644); + pid1 = getpid(); + + if (fd1 < 0) { + perror("Can't create file"); + ksft_exit_fail(); + } + + if (pipe(pipefd)) { + perror("Can't create pipe"); + ksft_exit_fail(); + } + + epollfd = epoll_create1(0); + if (epollfd < 0) { + perror("epoll_create1 failed"); + ksft_exit_fail(); + } + + memset(&ev, 0xff, sizeof(ev)); + ev.events = EPOLLIN | EPOLLOUT; + + if (epoll_ctl(epollfd, EPOLL_CTL_ADD, pipefd[0], &ev)) { + perror("epoll_ctl failed"); + ksft_exit_fail(); + } + + fddup = dup2(pipefd[1], duped_num); + if (fddup < 0) { + perror("dup2 failed"); + ksft_exit_fail(); + } + + if (epoll_ctl(epollfd, EPOLL_CTL_ADD, fddup, &ev)) { + perror("epoll_ctl failed"); + ksft_exit_fail(); + } + close(fddup); + + pid2 = fork(); + if (pid2 < 0) { + perror("fork failed"); + ksft_exit_fail(); + } + + if (!pid2) { + int pid2 = getpid(); + int ret; + + ksft_print_header(); + ksft_set_plan(3); + + fd2 = open(kpath, O_RDWR); + if (fd2 < 0) { + perror("Can't open file"); + ksft_exit_fail(); + } + + /* An example of output and arguments */ + printf("pid1: %6d pid2: %6d FD: %2ld FILES: %2ld VM: %2ld " + "FS: %2ld SIGHAND: %2ld IO: %2ld SYSVSEM: %2ld " + "INV: %2ld\n", + pid1, pid2, + sys_kcmp(pid1, pid2, KCMP_FILE, fd1, fd2), + sys_kcmp(pid1, pid2, KCMP_FILES, 0, 0), + sys_kcmp(pid1, pid2, KCMP_VM, 0, 0), + sys_kcmp(pid1, pid2, KCMP_FS, 0, 0), + sys_kcmp(pid1, pid2, KCMP_SIGHAND, 0, 0), + sys_kcmp(pid1, pid2, KCMP_IO, 0, 0), + sys_kcmp(pid1, pid2, KCMP_SYSVSEM, 0, 0), + + /* This one should fail */ + sys_kcmp(pid1, pid2, KCMP_TYPES + 1, 0, 0)); + + /* This one should return same fd */ + ret = sys_kcmp(pid1, pid2, KCMP_FILE, fd1, fd1); + if (ret) { + printf("FAIL: 0 expected but %d returned (%s)\n", + ret, strerror(errno)); + ksft_inc_fail_cnt(); + ret = -1; + } else { + printf("PASS: 0 returned as expected\n"); + ksft_inc_pass_cnt(); + } + + /* Compare with self */ + ret = sys_kcmp(pid1, pid1, KCMP_VM, 0, 0); + if (ret) { + printf("FAIL: 0 expected but %d returned (%s)\n", + ret, strerror(errno)); + ksft_inc_fail_cnt(); + ret = -1; + } else { + printf("PASS: 0 returned as expected\n"); + ksft_inc_pass_cnt(); + } + + /* Compare epoll target */ + epoll_slot = (struct kcmp_epoll_slot) { + .efd = epollfd, + .tfd = duped_num, + .toff = 0, + }; + ret = sys_kcmp(pid1, pid1, KCMP_EPOLL_TFD, pipefd[1], + (unsigned long)(void *)&epoll_slot); + if (ret) { + printf("FAIL: 0 expected but %d returned (%s)\n", + ret, strerror(errno)); + ksft_inc_fail_cnt(); + ret = -1; + } else { + printf("PASS: 0 returned as expected\n"); + ksft_inc_pass_cnt(); + } + + + if (ret) + ksft_exit_fail(); + else + ksft_exit_pass(); + } + + waitpid(pid2, &status, P_ALL); + + return 0; +} -- cgit v1.3.1