mirror of
https://github.com/torvalds/linux.git
synced 2026-04-18 06:44:00 -04:00
813f336269
Since commit f2e388a019 ("hrtimer: Reduce trace noise in hrtimer_start()"),
hrtimer_cancel tracepoint is no longer called when a hrtimer is re-armed. So
instead of a hrtimer_cancel followed by hrtimer_start tracepoint events, there
is now only a since hrtimer_start tracepoint event with the new was_armed field
set to 1, to indicated that the hrtimer was previously armed.
Update timer_start_deadlock accordingly so it traces hrtimer_start tracepoint
instead, with was_armed used as guard.
Signed-off-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
Tested-by: Mykyta Yatsenko <yatsenko@meta.com>
Acked-by: Mykyta Yatsenko <yatsenko@meta.com>
Link: https://lore.kernel.org/r/20260415120329.129192-1-shung-hsi.yu@suse.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
71 lines
1.5 KiB
C
71 lines
1.5 KiB
C
// SPDX-License-Identifier: GPL-2.0
|
|
/* Copyright (c) 2026 Meta Platforms, Inc. and affiliates. */
|
|
#include <vmlinux.h>
|
|
#include <bpf/bpf_helpers.h>
|
|
#include <bpf/bpf_tracing.h>
|
|
|
|
#define CLOCK_MONOTONIC 1
|
|
|
|
char _license[] SEC("license") = "GPL";
|
|
|
|
struct elem {
|
|
struct bpf_timer timer;
|
|
};
|
|
|
|
struct {
|
|
__uint(type, BPF_MAP_TYPE_ARRAY);
|
|
__uint(max_entries, 1);
|
|
__type(key, int);
|
|
__type(value, struct elem);
|
|
} timer_map SEC(".maps");
|
|
|
|
volatile int in_timer_start;
|
|
volatile int tp_called;
|
|
|
|
static int timer_cb(void *map, int *key, struct elem *value)
|
|
{
|
|
return 0;
|
|
}
|
|
|
|
SEC("tp_btf/hrtimer_start")
|
|
int BPF_PROG(tp_hrtimer_start, struct hrtimer *hrtimer, enum hrtimer_mode mode, bool was_armed)
|
|
{
|
|
struct bpf_timer *timer;
|
|
int key = 0;
|
|
|
|
if (!in_timer_start || !was_armed)
|
|
return 0;
|
|
|
|
tp_called = 1;
|
|
timer = bpf_map_lookup_elem(&timer_map, &key);
|
|
|
|
/*
|
|
* Call bpf_timer_start() from the tracepoint within hrtimer logic
|
|
* on the same timer to make sure it doesn't deadlock.
|
|
*/
|
|
bpf_timer_start(timer, 1000000000, 0);
|
|
return 0;
|
|
}
|
|
|
|
SEC("syscall")
|
|
int start_timer(void *ctx)
|
|
{
|
|
struct bpf_timer *timer;
|
|
int key = 0;
|
|
|
|
timer = bpf_map_lookup_elem(&timer_map, &key);
|
|
/* claude may complain here that there is no NULL check. Ignoring it. */
|
|
bpf_timer_init(timer, &timer_map, CLOCK_MONOTONIC);
|
|
bpf_timer_set_callback(timer, timer_cb);
|
|
|
|
/*
|
|
* call hrtimer_start() twice, so that 2nd call does
|
|
* trace_hrtimer_start(was_armed=1) tracepoint.
|
|
*/
|
|
in_timer_start = 1;
|
|
bpf_timer_start(timer, 1000000000, 0);
|
|
bpf_timer_start(timer, 1000000000, 0);
|
|
in_timer_start = 0;
|
|
return 0;
|
|
}
|