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staging: hv: Optimize adj_guesttime function and add more detailed comments

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Credits go to Joe Perches <joe@perches.com> for suggesting the changes.

Cc: Joe Perches <joe@perches.com>
Signed-off-by: Hank Janssen <hjanssen@microsoft.com>
Signed-off-by: Haiyang Zhang <haiyangz@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
Haiyang Zhang 2010-05-11 15:11:24 +00:00 committed by Greg Kroah-Hartman
parent ce7f638979
commit e9ec36030c
1 changed files with 23 additions and 10 deletions
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33
drivers/staging/hv/hv_utils.c
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@ -106,31 +106,44 @@ static void shutdown_onchannelcallback(void *context)
orderly_poweroff(false);
}
/*
* Synchronize time with host after reboot, restore, etc.
* Set guest time to host UTC time.
*/
static void adj_guesttime(u64 hosttime, u8 flags)
static inline void do_adj_guesttime(u64 hosttime)
{
s64 host_tns;
struct timespec host_ts;
static s32 scnt = 50;
host_tns = (hosttime - WLTIMEDELTA) * 100;
host_ts = ns_to_timespec(host_tns);
do_settimeofday(&host_ts);
}
/*
* Synchronize time with host after reboot, restore, etc.
*
* ICTIMESYNCFLAG_SYNC flag bit indicates reboot, restore events of the VM.
* After reboot the flag ICTIMESYNCFLAG_SYNC is included in the first time
* message after the timesync channel is opened. Since the hv_utils module is
* loaded after hv_vmbus, the first message is usually missed. The other
* thing is, systime is automatically set to emulated hardware clock which may
* not be UTC time or in the same time zone. So, to override these effects, we
* use the first 50 time samples for initial system time setting.
*/
static inline void adj_guesttime(u64 hosttime, u8 flags)
{
static s32 scnt = 50;
if ((flags & ICTIMESYNCFLAG_SYNC) != 0) {
do_settimeofday(&host_ts);
do_adj_guesttime(hosttime);
return;
}
if ((flags & ICTIMESYNCFLAG_SAMPLE) != 0 &&
scnt > 0) {
if ((flags & ICTIMESYNCFLAG_SAMPLE) != 0 && scnt > 0) {
scnt--;
do_settimeofday(&host_ts);
do_adj_guesttime(hosttime);
}
return;
}
/*