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/pager.c | 129 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 129 insertions(+) create mode 100644 tools/lib/subcmd/pager.c (limited to 'tools/lib/subcmd/pager.c') diff --git a/tools/lib/subcmd/pager.c b/tools/lib/subcmd/pager.c new file mode 100644 index 000000000..e3d47b59b --- /dev/null +++ b/tools/lib/subcmd/pager.c @@ -0,0 +1,129 @@ +// SPDX-License-Identifier: GPL-2.0 +#include +#include +#include +#include +#include +#include +#include "pager.h" +#include "run-command.h" +#include "sigchain.h" +#include "subcmd-config.h" + +/* + * This is split up from the rest of git so that we can do + * something different on Windows. + */ + +static int spawned_pager; +static int pager_columns; + +void pager_init(const char *pager_env) +{ + subcmd_config.pager_env = pager_env; +} + +static const char *forced_pager; + +void force_pager(const char *pager) +{ + forced_pager = pager; +} + +static void pager_preexec(void) +{ + /* + * Work around bug in "less" by not starting it until we + * have real input + */ + fd_set in; + fd_set exception; + + FD_ZERO(&in); + FD_ZERO(&exception); + FD_SET(0, &in); + FD_SET(0, &exception); + select(1, &in, NULL, &exception, NULL); + + setenv("LESS", "FRSX", 0); +} + +static const char *pager_argv[] = { "sh", "-c", NULL, NULL }; +static struct child_process pager_process; + +static void wait_for_pager(void) +{ + fflush(stdout); + fflush(stderr); + /* signal EOF to pager */ + close(1); + close(2); + finish_command(&pager_process); +} + +static void wait_for_pager_signal(int signo) +{ + wait_for_pager(); + sigchain_pop(signo); + raise(signo); +} + +void setup_pager(void) +{ + const char *pager = getenv(subcmd_config.pager_env); + struct winsize sz; + + if (forced_pager) + pager = forced_pager; + if (!isatty(1) && !forced_pager) + return; + if (ioctl(1, TIOCGWINSZ, &sz) == 0) + pager_columns = sz.ws_col; + if (!pager) + pager = getenv("PAGER"); + if (!(pager || access("/usr/bin/pager", X_OK))) + pager = "/usr/bin/pager"; + if (!(pager || access("/usr/bin/less", X_OK))) + pager = "/usr/bin/less"; + if (!pager) + pager = "cat"; + if (!*pager || !strcmp(pager, "cat")) + return; + + spawned_pager = 1; /* means we are emitting to terminal */ + + /* spawn the pager */ + pager_argv[2] = pager; + pager_process.argv = pager_argv; + pager_process.in = -1; + pager_process.preexec_cb = pager_preexec; + + if (start_command(&pager_process)) + return; + + /* original process continues, but writes to the pipe */ + dup2(pager_process.in, 1); + if (isatty(2)) + dup2(pager_process.in, 2); + close(pager_process.in); + + /* this makes sure that the parent terminates after the pager */ + sigchain_push_common(wait_for_pager_signal); + atexit(wait_for_pager); +} + +int pager_in_use(void) +{ + return spawned_pager; +} + +int pager_get_columns(void) +{ + char *s; + + s = getenv("COLUMNS"); + if (s) + return atoi(s); + + return (pager_columns ? pager_columns : 80) - 2; +} -- cgit v1.3.1