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/gpio/gpio-watch.c | 100 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 100 insertions(+) create mode 100644 tools/gpio/gpio-watch.c (limited to 'tools/gpio/gpio-watch.c') diff --git a/tools/gpio/gpio-watch.c b/tools/gpio/gpio-watch.c new file mode 100644 index 000000000..41e76d244 --- /dev/null +++ b/tools/gpio/gpio-watch.c @@ -0,0 +1,100 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * gpio-watch - monitor unrequested lines for property changes using the + * character device + * + * Copyright (C) 2019 BayLibre SAS + * Author: Bartosz Golaszewski + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +int main(int argc, char **argv) +{ + struct gpio_v2_line_info_changed chg; + struct gpio_v2_line_info req; + struct pollfd pfd; + int fd, i, j, ret; + char *event, *end; + ssize_t rd; + + if (argc < 3) + goto err_usage; + + fd = open(argv[1], O_RDWR | O_CLOEXEC); + if (fd < 0) { + perror("unable to open gpiochip"); + return EXIT_FAILURE; + } + + for (i = 0, j = 2; i < argc - 2; i++, j++) { + memset(&req, 0, sizeof(req)); + + req.offset = strtoul(argv[j], &end, 0); + if (*end != '\0') + goto err_usage; + + ret = ioctl(fd, GPIO_V2_GET_LINEINFO_WATCH_IOCTL, &req); + if (ret) { + perror("unable to set up line watch"); + return EXIT_FAILURE; + } + } + + pfd.fd = fd; + pfd.events = POLLIN | POLLPRI; + + for (;;) { + ret = poll(&pfd, 1, 5000); + if (ret < 0) { + perror("error polling the linechanged fd"); + return EXIT_FAILURE; + } else if (ret > 0) { + memset(&chg, 0, sizeof(chg)); + rd = read(pfd.fd, &chg, sizeof(chg)); + if (rd < 0 || rd != sizeof(chg)) { + if (rd != sizeof(chg)) + errno = EIO; + + perror("error reading line change event"); + return EXIT_FAILURE; + } + + switch (chg.event_type) { + case GPIO_V2_LINE_CHANGED_REQUESTED: + event = "requested"; + break; + case GPIO_V2_LINE_CHANGED_RELEASED: + event = "released"; + break; + case GPIO_V2_LINE_CHANGED_CONFIG: + event = "config changed"; + break; + default: + fprintf(stderr, + "invalid event type received from the kernel\n"); + return EXIT_FAILURE; + } + + printf("line %u: %s at %" PRIu64 "\n", + chg.info.offset, event, (uint64_t)chg.timestamp_ns); + } + } + + return 0; + +err_usage: + printf("%s: ...\n", argv[0]); + return EXIT_FAILURE; +} -- cgit v1.3.1