1 | /* Demo leapsecond deadlock |
2 | * by: John Stultz (john.stultz@linaro.org) |
3 | * (C) Copyright IBM 2012 |
4 | * (C) Copyright 2013, 2015 Linaro Limited |
5 | * Licensed under the GPL |
6 | * |
7 | * This test demonstrates leapsecond deadlock that is possible |
8 | * on kernels from 2.6.26 to 3.3. |
9 | * |
10 | * WARNING: THIS WILL LIKELY HARD HANG SYSTEMS AND MAY LOSE DATA |
11 | * RUN AT YOUR OWN RISK! |
12 | * To build: |
13 | * $ gcc leapcrash.c -o leapcrash -lrt |
14 | */ |
15 | |
16 | |
17 | |
18 | #include <stdio.h> |
19 | #include <stdlib.h> |
20 | #include <time.h> |
21 | #include <sys/time.h> |
22 | #include <sys/timex.h> |
23 | #include <string.h> |
24 | #include <signal.h> |
25 | #include "../kselftest.h" |
26 | |
27 | /* clear NTP time_status & time_state */ |
28 | int clear_time_state(void) |
29 | { |
30 | struct timex tx; |
31 | int ret; |
32 | |
33 | /* |
34 | * We have to call adjtime twice here, as kernels |
35 | * prior to 6b1859dba01c7 (included in 3.5 and |
36 | * -stable), had an issue with the state machine |
37 | * and wouldn't clear the STA_INS/DEL flag directly. |
38 | */ |
39 | tx.modes = ADJ_STATUS; |
40 | tx.status = STA_PLL; |
41 | ret = adjtimex(&tx); |
42 | |
43 | tx.modes = ADJ_STATUS; |
44 | tx.status = 0; |
45 | ret = adjtimex(&tx); |
46 | |
47 | return ret; |
48 | } |
49 | |
50 | /* Make sure we cleanup on ctrl-c */ |
51 | void handler(int unused) |
52 | { |
53 | clear_time_state(); |
54 | exit(0); |
55 | } |
56 | |
57 | |
58 | int main(void) |
59 | { |
60 | struct timex tx; |
61 | struct timespec ts; |
62 | time_t next_leap; |
63 | int count = 0; |
64 | |
65 | setbuf(stdout, NULL); |
66 | |
67 | signal(SIGINT, handler); |
68 | signal(SIGKILL, handler); |
69 | printf("This runs for a few minutes. Press ctrl-c to stop\n" ); |
70 | |
71 | clear_time_state(); |
72 | |
73 | |
74 | /* Get the current time */ |
75 | clock_gettime(CLOCK_REALTIME, &ts); |
76 | |
77 | /* Calculate the next possible leap second 23:59:60 GMT */ |
78 | next_leap = ts.tv_sec; |
79 | next_leap += 86400 - (next_leap % 86400); |
80 | |
81 | for (count = 0; count < 20; count++) { |
82 | struct timeval tv; |
83 | |
84 | |
85 | /* set the time to 2 seconds before the leap */ |
86 | tv.tv_sec = next_leap - 2; |
87 | tv.tv_usec = 0; |
88 | if (settimeofday(&tv, NULL)) { |
89 | printf("Error: You're likely not running with proper (ie: root) permissions\n" ); |
90 | return ksft_exit_fail(); |
91 | } |
92 | tx.modes = 0; |
93 | adjtimex(&tx); |
94 | |
95 | /* hammer on adjtime w/ STA_INS */ |
96 | while (tx.time.tv_sec < next_leap + 1) { |
97 | /* Set the leap second insert flag */ |
98 | tx.modes = ADJ_STATUS; |
99 | tx.status = STA_INS; |
100 | adjtimex(&tx); |
101 | } |
102 | clear_time_state(); |
103 | printf("." ); |
104 | fflush(stdout); |
105 | } |
106 | printf("[OK]\n" ); |
107 | return ksft_exit_pass(); |
108 | } |
109 | |