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authorJohn Stultz <johnstul@us.ibm.com>2007-11-26 20:42:19 +0100
committerIngo Molnar <mingo@elte.hu>2007-11-26 20:42:19 +0100
commit52bfb36050c8529d9031d2c2513b281a360922ec (patch)
tree7d116ece2ed21b8319e800efc0c2fd70818f01d3
parent8232fd625217dc641ed05dd238a8bb5c82828082 (diff)
time: add ADJ_OFFSET_SS_READ
Michael Kerrisk reported that a long standing bug in the adjtimex() system call causes glibc's adjtime(3) function to deliver the wrong results if 'delta' is NULL. add the ADJ_OFFSET_SS_READ API detail, which will be used by glibc to fix this API compatibility bug. Also see: http://bugzilla.kernel.org/show_bug.cgi?id=6761 [ mingo@elte.hu: added patch description and made it backwards compatible ] NOTE: the new flag is defined 0xa001 so that it returns -EINVAL on older kernels - this way glibc can use it safely. Suggested by Ulrich Drepper. Acked-by: Ulrich Drepper <drepper@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
-rw-r--r--include/linux/timex.h1
-rw-r--r--kernel/time/ntp.c9
2 files changed, 7 insertions, 3 deletions
diff --git a/include/linux/timex.h b/include/linux/timex.h
index 37ac3ff90fa..24c6a2b5951 100644
--- a/include/linux/timex.h
+++ b/include/linux/timex.h
@@ -137,6 +137,7 @@ struct timex {
#define ADJ_TIMECONST 0x0020 /* pll time constant */
#define ADJ_TICK 0x4000 /* tick value */
#define ADJ_OFFSET_SINGLESHOT 0x8001 /* old-fashioned adjtime */
+#define ADJ_OFFSET_SS_READ 0xa001 /* read-only adjtime */
/* xntp 3.4 compatibility names */
#define MOD_OFFSET ADJ_OFFSET
diff --git a/kernel/time/ntp.c b/kernel/time/ntp.c
index 14a2ecf2b31..e64efaf957e 100644
--- a/kernel/time/ntp.c
+++ b/kernel/time/ntp.c
@@ -249,10 +249,12 @@ int do_adjtimex(struct timex *txc)
/* Now we validate the data before disabling interrupts */
- if ((txc->modes & ADJ_OFFSET_SINGLESHOT) == ADJ_OFFSET_SINGLESHOT)
+ if ((txc->modes & ADJ_OFFSET_SINGLESHOT) == ADJ_OFFSET_SINGLESHOT) {
/* singleshot must not be used with any other mode bits */
- if (txc->modes != ADJ_OFFSET_SINGLESHOT)
+ if (txc->modes != ADJ_OFFSET_SINGLESHOT &&
+ txc->modes != ADJ_OFFSET_SS_READ)
return -EINVAL;
+ }
if (txc->modes != ADJ_OFFSET_SINGLESHOT && (txc->modes & ADJ_OFFSET))
/* adjustment Offset limited to +- .512 seconds */
@@ -372,7 +374,8 @@ int do_adjtimex(struct timex *txc)
leave: if ((time_status & (STA_UNSYNC|STA_CLOCKERR)) != 0)
result = TIME_ERROR;
- if ((txc->modes & ADJ_OFFSET_SINGLESHOT) == ADJ_OFFSET_SINGLESHOT)
+ if ((txc->modes == ADJ_OFFSET_SINGLESHOT) ||
+ (txc->modes == ADJ_OFFSET_SS_READ))
txc->offset = save_adjust;
else
txc->offset = ((long)shift_right(time_offset, SHIFT_UPDATE)) *