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/copyfile.c | 146 +++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 146 insertions(+) create mode 100644 tools/perf/util/copyfile.c (limited to 'tools/perf/util/copyfile.c') diff --git a/tools/perf/util/copyfile.c b/tools/perf/util/copyfile.c new file mode 100644 index 000000000..47e03de7c --- /dev/null +++ b/tools/perf/util/copyfile.c @@ -0,0 +1,146 @@ +// SPDX-License-Identifier: GPL-2.0 +#include "util/copyfile.h" +#include "util/namespaces.h" +#include +#include +#include +#include +#include +#include +#include +#include +#include + +static int slow_copyfile(const char *from, const char *to, struct nsinfo *nsi) +{ + int err = -1; + char *line = NULL; + size_t n; + FILE *from_fp, *to_fp; + struct nscookie nsc; + + nsinfo__mountns_enter(nsi, &nsc); + from_fp = fopen(from, "r"); + nsinfo__mountns_exit(&nsc); + if (from_fp == NULL) + goto out; + + to_fp = fopen(to, "w"); + if (to_fp == NULL) + goto out_fclose_from; + + while (getline(&line, &n, from_fp) > 0) + if (fputs(line, to_fp) == EOF) + goto out_fclose_to; + err = 0; +out_fclose_to: + fclose(to_fp); + free(line); +out_fclose_from: + fclose(from_fp); +out: + return err; +} + +int copyfile_offset(int ifd, loff_t off_in, int ofd, loff_t off_out, u64 size) +{ + void *ptr; + loff_t pgoff; + + pgoff = off_in & ~(page_size - 1); + off_in -= pgoff; + + ptr = mmap(NULL, off_in + size, PROT_READ, MAP_PRIVATE, ifd, pgoff); + if (ptr == MAP_FAILED) + return -1; + + while (size) { + ssize_t ret = pwrite(ofd, ptr + off_in, size, off_out); + if (ret < 0 && errno == EINTR) + continue; + if (ret <= 0) + break; + + size -= ret; + off_in += ret; + off_out += ret; + } + munmap(ptr, off_in + size); + + return size ? -1 : 0; +} + +static int copyfile_mode_ns(const char *from, const char *to, mode_t mode, + struct nsinfo *nsi) +{ + int fromfd, tofd; + struct stat st; + int err; + char *tmp = NULL, *ptr = NULL; + struct nscookie nsc; + + nsinfo__mountns_enter(nsi, &nsc); + err = stat(from, &st); + nsinfo__mountns_exit(&nsc); + if (err) + goto out; + err = -1; + + /* extra 'x' at the end is to reserve space for '.' */ + if (asprintf(&tmp, "%s.XXXXXXx", to) < 0) { + tmp = NULL; + goto out; + } + ptr = strrchr(tmp, '/'); + if (!ptr) + goto out; + ptr = memmove(ptr + 1, ptr, strlen(ptr) - 1); + *ptr = '.'; + + tofd = mkstemp(tmp); + if (tofd < 0) + goto out; + + if (st.st_size == 0) { /* /proc? do it slowly... */ + err = slow_copyfile(from, tmp, nsi); + if (!err && fchmod(tofd, mode)) + err = -1; + goto out_close_to; + } + + if (fchmod(tofd, mode)) + goto out_close_to; + + nsinfo__mountns_enter(nsi, &nsc); + fromfd = open(from, O_RDONLY); + nsinfo__mountns_exit(&nsc); + if (fromfd < 0) + goto out_close_to; + + err = copyfile_offset(fromfd, 0, tofd, 0, st.st_size); + + close(fromfd); +out_close_to: + close(tofd); + if (!err) + err = link(tmp, to); + unlink(tmp); +out: + free(tmp); + return err; +} + +int copyfile_ns(const char *from, const char *to, struct nsinfo *nsi) +{ + return copyfile_mode_ns(from, to, 0755, nsi); +} + +int copyfile_mode(const char *from, const char *to, mode_t mode) +{ + return copyfile_mode_ns(from, to, mode, NULL); +} + +int copyfile(const char *from, const char *to) +{ + return copyfile_mode(from, to, 0755); +} -- cgit v1.3.1