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/lib/subcmd/run-command.c | 358 +++++++++++++++++++++++++++++++++++++++++ 1 file changed, 358 insertions(+) create mode 100644 tools/lib/subcmd/run-command.c (limited to 'tools/lib/subcmd/run-command.c') diff --git a/tools/lib/subcmd/run-command.c b/tools/lib/subcmd/run-command.c new file mode 100644 index 000000000..bd21b8bfd --- /dev/null +++ b/tools/lib/subcmd/run-command.c @@ -0,0 +1,358 @@ +// SPDX-License-Identifier: GPL-2.0 +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include "subcmd-util.h" +#include "run-command.h" +#include "exec-cmd.h" + +#define STRERR_BUFSIZE 128 + +static inline void close_pair(int fd[2]) +{ + close(fd[0]); + close(fd[1]); +} + +static inline void dup_devnull(int to) +{ + int fd = open("/dev/null", O_RDWR); + dup2(fd, to); + close(fd); +} + +int start_command(struct child_process *cmd) +{ + int need_in, need_out, need_err; + int fdin[2], fdout[2], fderr[2]; + char sbuf[STRERR_BUFSIZE]; + + /* + * In case of errors we must keep the promise to close FDs + * that have been passed in via ->in and ->out. + */ + + need_in = !cmd->no_stdin && cmd->in < 0; + if (need_in) { + if (pipe(fdin) < 0) { + if (cmd->out > 0) + close(cmd->out); + return -ERR_RUN_COMMAND_PIPE; + } + cmd->in = fdin[1]; + } + + need_out = !cmd->no_stdout + && !cmd->stdout_to_stderr + && cmd->out < 0; + if (need_out) { + if (pipe(fdout) < 0) { + if (need_in) + close_pair(fdin); + else if (cmd->in) + close(cmd->in); + return -ERR_RUN_COMMAND_PIPE; + } + cmd->out = fdout[0]; + } + + need_err = !cmd->no_stderr && cmd->err < 0; + if (need_err) { + if (pipe(fderr) < 0) { + if (need_in) + close_pair(fdin); + else if (cmd->in) + close(cmd->in); + if (need_out) + close_pair(fdout); + else if (cmd->out) + close(cmd->out); + return -ERR_RUN_COMMAND_PIPE; + } + cmd->err = fderr[0]; + } + + fflush(NULL); + cmd->pid = fork(); + if (!cmd->pid) { + if (cmd->no_stdin) + dup_devnull(0); + else if (need_in) { + dup2(fdin[0], 0); + close_pair(fdin); + } else if (cmd->in) { + dup2(cmd->in, 0); + close(cmd->in); + } + + if (cmd->no_stderr) + dup_devnull(2); + else if (need_err) { + dup2(fderr[1], 2); + close_pair(fderr); + } + + if (cmd->no_stdout) + dup_devnull(1); + else if (cmd->stdout_to_stderr) + dup2(2, 1); + else if (need_out) { + dup2(fdout[1], 1); + close_pair(fdout); + } else if (cmd->out > 1) { + dup2(cmd->out, 1); + close(cmd->out); + } + + if (cmd->dir && chdir(cmd->dir)) + die("exec %s: cd to %s failed (%s)", cmd->argv[0], + cmd->dir, str_error_r(errno, sbuf, sizeof(sbuf))); + if (cmd->env) { + for (; *cmd->env; cmd->env++) { + if (strchr(*cmd->env, '=')) + putenv((char*)*cmd->env); + else + unsetenv(*cmd->env); + } + } + if (cmd->preexec_cb) + cmd->preexec_cb(); + if (cmd->no_exec_cmd) + exit(cmd->no_exec_cmd(cmd)); + if (cmd->exec_cmd) { + execv_cmd(cmd->argv); + } else { + execvp(cmd->argv[0], (char *const*) cmd->argv); + } + exit(127); + } + + if (cmd->pid < 0) { + int err = errno; + if (need_in) + close_pair(fdin); + else if (cmd->in) + close(cmd->in); + if (need_out) + close_pair(fdout); + else if (cmd->out) + close(cmd->out); + if (need_err) + close_pair(fderr); + return err == ENOENT ? + -ERR_RUN_COMMAND_EXEC : + -ERR_RUN_COMMAND_FORK; + } + + if (need_in) + close(fdin[0]); + else if (cmd->in) + close(cmd->in); + + if (need_out) + close(fdout[1]); + else if (cmd->out) + close(cmd->out); + + if (need_err) + close(fderr[1]); + + return 0; +} + +static int wait_or_whine(struct child_process *cmd, bool block) +{ + bool finished; + int result; + + if (cmd->pid <= 0) { + cmd->finished = 1; + if (cmd->pid < 0 && cmd->finish_result == 0) + cmd->finish_result = -ERR_RUN_COMMAND_FORK; + return cmd->finish_result; + } + + finished = cmd->finished; + result = cmd->finish_result; + + while (!finished) { + int status, code; + pid_t waiting = waitpid(cmd->pid, &status, block ? 0 : WNOHANG); + + if (!block && waiting == 0) + break; + + if (waiting < 0 && errno == EINTR) + continue; + + finished = true; + if (waiting < 0) { + char sbuf[STRERR_BUFSIZE]; + + fprintf(stderr, " Error: waitpid failed (%s)", + str_error_r(errno, sbuf, sizeof(sbuf))); + result = -ERR_RUN_COMMAND_WAITPID; + } else if (waiting != cmd->pid) { + result = -ERR_RUN_COMMAND_WAITPID_WRONG_PID; + } else if (WIFSIGNALED(status)) { + result = -ERR_RUN_COMMAND_WAITPID_SIGNAL; + } else if (!WIFEXITED(status)) { + result = -ERR_RUN_COMMAND_WAITPID_NOEXIT; + } else { + code = WEXITSTATUS(status); + switch (code) { + case 127: + result = -ERR_RUN_COMMAND_EXEC; + break; + case 0: + result = 0; + break; + default: + result = -code; + break; + } + } + } + if (finished) { + cmd->finished = 1; + cmd->finish_result = result; + } + return result; +} + +/* + * Conservative estimate of number of characaters needed to hold an a decoded + * integer, assume each 3 bits needs a character byte and plus a possible sign + * character. + */ +#ifndef is_signed_type +#define is_signed_type(type) (((type)(-1)) < (type)1) +#endif +#define MAX_STRLEN_TYPE(type) (sizeof(type) * 8 / 3 + (is_signed_type(type) ? 1 : 0)) + +int check_if_command_finished(struct child_process *cmd) +{ +#ifdef __linux__ + char filename[6 + MAX_STRLEN_TYPE(typeof(cmd->pid)) + 7 + 1]; + char status_line[256]; + FILE *status_file; +#endif + + if (cmd->finished) + return 1; + if (cmd->pid <= 0) { + cmd->finished = 1; + if (cmd->pid < 0 && cmd->finish_result == 0) + cmd->finish_result = -ERR_RUN_COMMAND_FORK; + return 1; + } + +#ifdef __linux__ + /* + * Check by reading /proc//status as calling waitpid causes + * stdout/stderr to be closed and data lost. + */ + sprintf(filename, "/proc/%u/status", cmd->pid); + status_file = fopen(filename, "r"); + if (status_file == NULL) { + int status; + pid_t waiting; + + /* + * fopen() can fail with ENOENT if the process has been reaped. + * It can also fail with EMFILE/ENFILE if RLIMIT_NOFILE is reached. + * In those cases, use waitpid(..., WNOHANG) to robustly check + * and reap the process if it has exited. + */ + if (errno == ENOENT) + return 1; + + waiting = waitpid(cmd->pid, &status, WNOHANG); + if (waiting == cmd->pid) { + int result; + int code; + + cmd->finished = 1; + if (WIFSIGNALED(status)) { + result = -ERR_RUN_COMMAND_WAITPID_SIGNAL; + } else if (!WIFEXITED(status)) { + result = -ERR_RUN_COMMAND_WAITPID_NOEXIT; + } else { + code = WEXITSTATUS(status); + switch (code) { + case 127: + result = -ERR_RUN_COMMAND_EXEC; + break; + case 0: + result = 0; + break; + default: + result = -code; + break; + } + } + cmd->finish_result = result; + return 1; + } + if (waiting < 0 && (errno == ECHILD || errno == ESRCH)) + return 1; + return 0; + } + while (fgets(status_line, sizeof(status_line), status_file) != NULL) { + char *p; + + if (strncmp(status_line, "State:", 6)) + continue; + + fclose(status_file); + p = status_line + 6; + while (isspace(*p)) + p++; + return *p == 'Z' ? 1 : 0; + } + /* Read failed assume finish_command was called. */ + fclose(status_file); + return 1; +#else + wait_or_whine(cmd, /*block=*/false); + return cmd->finished; +#endif +} + +int finish_command(struct child_process *cmd) +{ + return wait_or_whine(cmd, /*block=*/true); +} + +int run_command(struct child_process *cmd) +{ + int code = start_command(cmd); + if (code) + return code; + return finish_command(cmd); +} + +static void prepare_run_command_v_opt(struct child_process *cmd, + const char **argv, + int opt) +{ + memset(cmd, 0, sizeof(*cmd)); + cmd->argv = argv; + cmd->no_stdin = opt & RUN_COMMAND_NO_STDIN ? 1 : 0; + cmd->exec_cmd = opt & RUN_EXEC_CMD ? 1 : 0; + cmd->stdout_to_stderr = opt & RUN_COMMAND_STDOUT_TO_STDERR ? 1 : 0; +} + +int run_command_v_opt(const char **argv, int opt) +{ + struct child_process cmd; + prepare_run_command_v_opt(&cmd, argv, opt); + return run_command(&cmd); +} -- cgit v1.3.1