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Message-Id: <1174696834.5690.14.camel@localhost.localdomain>
Date: Fri, 23 Mar 2007 17:40:34 -0700
From: john stultz <johnstul@...ibm.com>
To: Andrew Morton <akpm@...l.org>
Cc: Roman Zippel <zippel@...ux-m68k.org>, Ingo Molnar <mingo@...e.hu>,
Thomas Gleixner <tglx@...utronix.de>,
lkml <linux-kernel@...r.kernel.org>
Subject: [PATCH] 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.
thanks
-john
Signed-off-by: John Stultz <johnstul@...ibm.com>
diff --git a/kernel/time/ntp.c b/kernel/time/ntp.c
index eb12509..eaa3d24 100644
--- a/kernel/time/ntp.c
+++ b/kernel/time/ntp.c
@@ -32,7 +32,7 @@ #define MAX_TICKADJ_SCALED (((u64)(MAX_T
/* 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_
*/
int do_adjtimex(struct timex *txc)
{
- long ltemp, mtemp, save_adjust;
+ long mtemp, save_adjust;
s64 freq_adj, temp64;
int result;
@@ -277,14 +277,14 @@ #endif
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 @@ #endif
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 +314,8 @@ #endif
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;
+ do_div(time_offset, NTP_INTERVAL_FREQ);
+ time_offset <<= SHIFT_UPDATE;
} /* STA_PLL */
} /* txc->modes & ADJ_OFFSET */
if (txc->modes & ADJ_TICK)
@@ -330,7 +330,7 @@ leave: if ((time_status & (STA_UNSYNC|ST
if ((txc->modes & ADJ_OFFSET_SINGLESHOT) == ADJ_OFFSET_SINGLESHOT)
txc->offset = save_adjust;
else
- txc->offset = shift_right(time_offset, SHIFT_UPDATE)
+ txc->offset = ((long)shift_right(time_offset, SHIFT_UPDATE))
* NTP_INTERVAL_FREQ / 1000;
txc->freq = (time_freq / NSEC_PER_USEC)
<< (SHIFT_USEC - SHIFT_NSEC);
-
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