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/stream.c | 341 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 341 insertions(+) create mode 100644 tools/perf/util/stream.c (limited to 'tools/perf/util/stream.c') diff --git a/tools/perf/util/stream.c b/tools/perf/util/stream.c new file mode 100644 index 000000000..7bccd2378 --- /dev/null +++ b/tools/perf/util/stream.c @@ -0,0 +1,341 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Compare and figure out the top N hottest streams + * Copyright (c) 2020, Intel Corporation. + * Author: Jin Yao + */ + +#include +#include +#include +#include "debug.h" +#include "hist.h" +#include "sort.h" +#include "stream.h" +#include "evlist.h" + +static void evsel_streams__delete(struct evsel_streams *es, int nr_evsel) +{ + for (int i = 0; i < nr_evsel; i++) + zfree(&es[i].streams); + + free(es); +} + +void evlist_streams__delete(struct evlist_streams *els) +{ + evsel_streams__delete(els->ev_streams, els->nr_evsel); + free(els); +} + +static struct evlist_streams *evlist_streams__new(int nr_evsel, + int nr_streams_max) +{ + struct evlist_streams *els; + struct evsel_streams *es; + + els = zalloc(sizeof(*els)); + if (!els) + return NULL; + + es = calloc(nr_evsel, sizeof(struct evsel_streams)); + if (!es) { + free(els); + return NULL; + } + + for (int i = 0; i < nr_evsel; i++) { + struct evsel_streams *s = &es[i]; + + s->streams = calloc(nr_streams_max, sizeof(struct stream)); + if (!s->streams) + goto err; + + s->nr_streams_max = nr_streams_max; + } + + els->ev_streams = es; + els->nr_evsel = nr_evsel; + return els; + +err: + evsel_streams__delete(es, nr_evsel); + return NULL; +} + +/* + * The cnodes with high hit number are hot callchains. + */ +static void evsel_streams__set_hot_cnode(struct evsel_streams *es, + struct callchain_node *cnode) +{ + int i, idx = 0; + u64 hit; + + if (es->nr_streams < es->nr_streams_max) { + i = es->nr_streams; + es->streams[i].cnode = cnode; + es->nr_streams++; + return; + } + + /* + * Considering a few number of hot streams, only use simple + * way to find the cnode with smallest hit number and replace. + */ + hit = (es->streams[0].cnode)->hit; + for (i = 1; i < es->nr_streams; i++) { + if ((es->streams[i].cnode)->hit < hit) { + hit = (es->streams[i].cnode)->hit; + idx = i; + } + } + + if (cnode->hit > hit) + es->streams[idx].cnode = cnode; +} + +static void update_hot_callchain(struct hist_entry *he, + struct evsel_streams *es) +{ + struct rb_root *root = &he->sorted_chain; + struct rb_node *rb_node = rb_first(root); + struct callchain_node *cnode; + + while (rb_node) { + cnode = rb_entry(rb_node, struct callchain_node, rb_node); + evsel_streams__set_hot_cnode(es, cnode); + rb_node = rb_next(rb_node); + } +} + +static void init_hot_callchain(struct hists *hists, struct evsel_streams *es) +{ + struct rb_node *next = rb_first_cached(&hists->entries); + + while (next) { + struct hist_entry *he; + + he = rb_entry(next, struct hist_entry, rb_node); + update_hot_callchain(he, es); + next = rb_next(&he->rb_node); + } + + es->streams_hits = callchain_total_hits(hists); +} + +static int evlist__init_callchain_streams(struct evlist *evlist, + struct evlist_streams *els) +{ + struct evsel_streams *es = els->ev_streams; + struct evsel *pos; + int i = 0; + + BUG_ON(els->nr_evsel < evlist__nr_entries(evlist)); + + evlist__for_each_entry(evlist, pos) { + struct hists *hists = evsel__hists(pos); + + hists__output_resort(hists, NULL); + init_hot_callchain(hists, &es[i]); + es[i].evsel = pos; + i++; + } + + return 0; +} + +struct evlist_streams *evlist__create_streams(struct evlist *evlist, + int nr_streams_max) +{ + int nr_evsel = evlist__nr_entries(evlist), ret = -1; + struct evlist_streams *els = evlist_streams__new(nr_evsel, + nr_streams_max); + + if (!els) + return NULL; + + ret = evlist__init_callchain_streams(evlist, els); + if (ret) { + evlist_streams__delete(els); + return NULL; + } + + return els; +} + +struct evsel_streams *evsel_streams__entry(struct evlist_streams *els, + const struct evsel *evsel) +{ + struct evsel_streams *es = els->ev_streams; + + for (int i = 0; i < els->nr_evsel; i++) { + if (es[i].evsel == evsel) + return &es[i]; + } + + return NULL; +} + +static struct stream *stream__callchain_match(struct stream *base_stream, + struct evsel_streams *es_pair) +{ + for (int i = 0; i < es_pair->nr_streams; i++) { + struct stream *pair_stream = &es_pair->streams[i]; + + if (callchain_cnode_matched(base_stream->cnode, + pair_stream->cnode)) { + return pair_stream; + } + } + + return NULL; +} + +static struct stream *stream__match(struct stream *base_stream, + struct evsel_streams *es_pair) +{ + return stream__callchain_match(base_stream, es_pair); +} + +static void stream__link(struct stream *base_stream, struct stream *pair_stream) +{ + base_stream->pair_cnode = pair_stream->cnode; + pair_stream->pair_cnode = base_stream->cnode; +} + +void evsel_streams__match(struct evsel_streams *es_base, + struct evsel_streams *es_pair) +{ + for (int i = 0; i < es_base->nr_streams; i++) { + struct stream *base_stream = &es_base->streams[i]; + struct stream *pair_stream; + + pair_stream = stream__match(base_stream, es_pair); + if (pair_stream) + stream__link(base_stream, pair_stream); + } +} + +static void print_callchain_pair(struct stream *base_stream, int idx, + struct evsel_streams *es_base, + struct evsel_streams *es_pair) +{ + struct callchain_node *base_cnode = base_stream->cnode; + struct callchain_node *pair_cnode = base_stream->pair_cnode; + struct callchain_list *base_chain, *pair_chain; + char buf1[512], buf2[512], cbuf1[256], cbuf2[256]; + char *s1, *s2; + double pct; + + printf("\nhot chain pair %d:\n", idx); + + pct = (double)base_cnode->hit / (double)es_base->streams_hits; + scnprintf(buf1, sizeof(buf1), "cycles: %ld, hits: %.2f%%", + callchain_avg_cycles(base_cnode), pct * 100.0); + + pct = (double)pair_cnode->hit / (double)es_pair->streams_hits; + scnprintf(buf2, sizeof(buf2), "cycles: %ld, hits: %.2f%%", + callchain_avg_cycles(pair_cnode), pct * 100.0); + + printf("%35s\t%35s\n", buf1, buf2); + + printf("%35s\t%35s\n", + "---------------------------", + "--------------------------"); + + pair_chain = list_first_entry(&pair_cnode->val, + struct callchain_list, + list); + + list_for_each_entry(base_chain, &base_cnode->val, list) { + if (&pair_chain->list == &pair_cnode->val) + return; + + s1 = callchain_list__sym_name(base_chain, cbuf1, sizeof(cbuf1), + false); + s2 = callchain_list__sym_name(pair_chain, cbuf2, sizeof(cbuf2), + false); + + scnprintf(buf1, sizeof(buf1), "%35s\t%35s", s1, s2); + printf("%s\n", buf1); + pair_chain = list_next_entry(pair_chain, list); + } +} + +static void print_stream_callchain(struct stream *stream, int idx, + struct evsel_streams *es, bool pair) +{ + struct callchain_node *cnode = stream->cnode; + struct callchain_list *chain; + char buf[512], cbuf[256], *s; + double pct; + + printf("\nhot chain %d:\n", idx); + + pct = (double)cnode->hit / (double)es->streams_hits; + scnprintf(buf, sizeof(buf), "cycles: %ld, hits: %.2f%%", + callchain_avg_cycles(cnode), pct * 100.0); + + if (pair) { + printf("%35s\t%35s\n", "", buf); + printf("%35s\t%35s\n", + "", "--------------------------"); + } else { + printf("%35s\n", buf); + printf("%35s\n", "--------------------------"); + } + + list_for_each_entry(chain, &cnode->val, list) { + s = callchain_list__sym_name(chain, cbuf, sizeof(cbuf), false); + + if (pair) + scnprintf(buf, sizeof(buf), "%35s\t%35s", "", s); + else + scnprintf(buf, sizeof(buf), "%35s", s); + + printf("%s\n", buf); + } +} + +static void callchain_streams_report(struct evsel_streams *es_base, + struct evsel_streams *es_pair) +{ + struct stream *base_stream; + int i, idx = 0; + + printf("[ Matched hot streams ]\n"); + for (i = 0; i < es_base->nr_streams; i++) { + base_stream = &es_base->streams[i]; + if (base_stream->pair_cnode) { + print_callchain_pair(base_stream, ++idx, + es_base, es_pair); + } + } + + idx = 0; + printf("\n[ Hot streams in old perf data only ]\n"); + for (i = 0; i < es_base->nr_streams; i++) { + base_stream = &es_base->streams[i]; + if (!base_stream->pair_cnode) { + print_stream_callchain(base_stream, ++idx, + es_base, false); + } + } + + idx = 0; + printf("\n[ Hot streams in new perf data only ]\n"); + for (i = 0; i < es_pair->nr_streams; i++) { + base_stream = &es_pair->streams[i]; + if (!base_stream->pair_cnode) { + print_stream_callchain(base_stream, ++idx, + es_pair, true); + } + } +} + +void evsel_streams__report(struct evsel_streams *es_base, + struct evsel_streams *es_pair) +{ + return callchain_streams_report(es_base, es_pair); +} -- cgit v1.3.1