Messages in this thread Patch in this message | | | Date | Sun, 31 May 2015 13:10:07 +0800 | From | Wang YanQing <> | Subject | [PATCH v2] timekeeping: always make sure wall_to_monotonic isn't positive |
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I meet two issues on an IMX6 development board without enable RTC device(so timekeeping_init will initialize the boot time and monotonic to 0).
Issue 1:exportfs -a generate: "exportfs: /opt/nfs/arm does not support NFS export" Issue 2:cat /proc/stat: "btime 4294967236"
Exact reproduction of the same issues on x86 after run below code: " int main(void) { struct timeval val; int ret;
val.tv_sec = 0; val.tv_usec = 0; ret = settimeofday(&val, NULL); return 0; } " Reason: The reason is positive wall_to_monotonic push boot time back to the time before Epoch, getboottime will return negative value.
In issue 1: negative boot time cause get_expiry overflow time_t when input expire time is 2147483647, then cache_flush always clear entries just added in ip_map_parse. In issue 2: show_stat use "unsigned long" to print negative value return by getboottime.
This patch fix these two issues.
Note: this patch will cause we can't use settimeofday with time earlier than current time on system which timekeeping_init initialize the xtime, boot and monotonic to 0 before set current time to a more reasonable time point.
Signed-off-by: Wang YanQing <udknight@gmail.com> --- Changes v1-v2: 1: fix subject, use "isn't positive" instead of "is negative". 2: rewrite changelog. 3: simplify code as suggested by John Stultz.
It really take me some times to realize how stupid and buggy the version 1 patch is, but I am ready to be told this version is even stupider:)
Thanks.
kernel/time/timekeeping.c | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-)
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c index 0d784b3..b501aa6 100644 --- a/kernel/time/timekeeping.c +++ b/kernel/time/timekeeping.c @@ -895,6 +895,7 @@ int do_settimeofday64(const struct timespec64 *ts) struct timekeeper *tk = &tk_core.timekeeper; struct timespec64 ts_delta, xt; unsigned long flags; + int ret = 0; if (!timespec64_valid_strict(ts)) return -EINVAL; @@ -908,10 +909,15 @@ int do_settimeofday64(const struct timespec64 *ts) ts_delta.tv_sec = ts->tv_sec - xt.tv_sec; ts_delta.tv_nsec = ts->tv_nsec - xt.tv_nsec; + if (timespec64_compare(&tk->wall_to_monotonic, &ts_delta) > 0) { + ret = -EINVAL; + goto out; + } + tk_set_wall_to_mono(tk, timespec64_sub(tk->wall_to_monotonic, ts_delta)); tk_set_xtime(tk, ts); - +out: timekeeping_update(tk, TK_CLEAR_NTP | TK_MIRROR | TK_CLOCK_WAS_SET); write_seqcount_end(&tk_core.seq); @@ -920,7 +926,7 @@ int do_settimeofday64(const struct timespec64 *ts) /* signal hrtimers about time change */ clock_was_set(); - return 0; + return ret; } EXPORT_SYMBOL(do_settimeofday64); @@ -949,7 +955,8 @@ int timekeeping_inject_offset(struct timespec *ts) /* Make sure the proposed value is valid */ tmp = timespec64_add(tk_xtime(tk), ts64); - if (!timespec64_valid_strict(&tmp)) { + if (timespec64_compare(&tk->wall_to_monotonic, &ts64) > 0 || + !timespec64_valid_strict(&tmp)) { ret = -EINVAL; goto error; } -- 1.8.5.6.2.g3d8a54e.dirty
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