diff options
| author | john stultz | 2007-03-26 21:32:26 -0800 |
|---|---|---|
| committer | Linus Torvalds | 2007-03-27 09:05:15 -0700 |
| commit | d62ac21aa075c8ddf3d02a98d28afce635e77e8e (patch) | |
| tree | d315a4aaa57b219c151a5e2d9ae0e557517a0bd2 /kernel | |
| parent | b92c4f922b2e8c70f8790d42e45bb9401c57be63 (diff) | |
[PATCH] ntp: avoid time_offset overflows
I've been seeing some odd NTP behavior recently on a few boxes and
finally narrowed it down to time_offset overflowing when converted to
SHIFT_UPDATE units (which was a side effect from my HZfreeNTP patch).
This patch converts time_offset from a long to a s64 which resolves the
issue.
[tglx@linutronix.de: signedness fixes]
Signed-off-by: John Stultz <johnstul@us.ibm.com>
Cc: Roman Zippel <zippel@linux-m68k.org>
Cc: john stultz <johnstul@us.ibm.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/time/ntp.c | 30 |
1 files changed, 16 insertions, 14 deletions
diff --git a/kernel/time/ntp.c b/kernel/time/ntp.c index eb12509e00bd..cb25649c6f50 100644 --- a/kernel/time/ntp.c +++ b/kernel/time/ntp.c @@ -32,7 +32,7 @@ static u64 tick_length, tick_length_base; /* TIME_ERROR prevents overwriting the CMOS clock */ static int time_state = TIME_OK; /* clock synchronization status */ int time_status = STA_UNSYNC; /* clock status bits */ -static long time_offset; /* time adjustment (ns) */ +static s64 time_offset; /* time adjustment (ns) */ static long time_constant = 2; /* pll time constant */ long time_maxerror = NTP_PHASE_LIMIT; /* maximum error (us) */ long time_esterror = NTP_PHASE_LIMIT; /* estimated error (us) */ @@ -196,7 +196,7 @@ void __attribute__ ((weak)) notify_arch_cmos_timer(void) */ int do_adjtimex(struct timex *txc) { - long ltemp, mtemp, save_adjust; + long mtemp, save_adjust, rem; s64 freq_adj, temp64; int result; @@ -277,14 +277,14 @@ int do_adjtimex(struct timex *txc) time_adjust = txc->offset; } else if (time_status & STA_PLL) { - ltemp = txc->offset * NSEC_PER_USEC; + time_offset = txc->offset * NSEC_PER_USEC; /* * Scale the phase adjustment and * clamp to the operating range. */ - time_offset = min(ltemp, MAXPHASE * NSEC_PER_USEC); - time_offset = max(time_offset, -MAXPHASE * NSEC_PER_USEC); + time_offset = min(time_offset, (s64)MAXPHASE * NSEC_PER_USEC); + time_offset = max(time_offset, (s64)-MAXPHASE * NSEC_PER_USEC); /* * Select whether the frequency is to be controlled @@ -297,11 +297,11 @@ int do_adjtimex(struct timex *txc) mtemp = xtime.tv_sec - time_reftime; time_reftime = xtime.tv_sec; - freq_adj = (s64)time_offset * mtemp; + freq_adj = time_offset * mtemp; freq_adj = shift_right(freq_adj, time_constant * 2 + (SHIFT_PLL + 2) * 2 - SHIFT_NSEC); if (mtemp >= MINSEC && (time_status & STA_FLL || mtemp > MAXSEC)) { - temp64 = (s64)time_offset << (SHIFT_NSEC - SHIFT_FLL); + temp64 = time_offset << (SHIFT_NSEC - SHIFT_FLL); if (time_offset < 0) { temp64 = -temp64; do_div(temp64, mtemp); @@ -314,8 +314,10 @@ int do_adjtimex(struct timex *txc) freq_adj += time_freq; freq_adj = min(freq_adj, (s64)MAXFREQ_NSEC); time_freq = max(freq_adj, (s64)-MAXFREQ_NSEC); - time_offset = (time_offset / NTP_INTERVAL_FREQ) - << SHIFT_UPDATE; + time_offset = div_long_long_rem_signed(time_offset, + NTP_INTERVAL_FREQ, + &rem); + time_offset <<= SHIFT_UPDATE; } /* STA_PLL */ } /* txc->modes & ADJ_OFFSET */ if (txc->modes & ADJ_TICK) @@ -328,12 +330,12 @@ leave: if ((time_status & (STA_UNSYNC|STA_CLOCKERR)) != 0) result = TIME_ERROR; if ((txc->modes & ADJ_OFFSET_SINGLESHOT) == ADJ_OFFSET_SINGLESHOT) - txc->offset = save_adjust; + txc->offset = save_adjust; else - txc->offset = shift_right(time_offset, SHIFT_UPDATE) - * NTP_INTERVAL_FREQ / 1000; - txc->freq = (time_freq / NSEC_PER_USEC) - << (SHIFT_USEC - SHIFT_NSEC); + txc->offset = ((long)shift_right(time_offset, SHIFT_UPDATE)) * + NTP_INTERVAL_FREQ / 1000; + txc->freq = (time_freq / NSEC_PER_USEC) << + (SHIFT_USEC - SHIFT_NSEC); txc->maxerror = time_maxerror; txc->esterror = time_esterror; txc->status = time_status; |