From 4307d1e5ada595c87f9a4d16db16ba5edb70dcb1 Mon Sep 17 00:00:00 2001 From: Ingo Molnar Date: Wed, 7 Nov 2007 18:37:48 +0100 Subject: x86: ignore the sys_getcpu() tcache parameter dont use the vgetcpu tcache - it's causing problems with tasks migrating, they'll see the old cache up to a jiffy after the migration, further increasing the costs of the migration. In the worst case they see a complete bogus information from the tcache, when a sys_getcpu() call "invalidated" the cache info by incrementing the jiffies _and_ the cpuid info in the cache and the following vdso_getcpu() call happens after vdso_jiffies have been incremented. Signed-off-by: Ingo Molnar Signed-off-by: Ulrich Drepper Signed-off-by: Thomas Gleixner --- kernel/sys.c | 20 +------------------- 1 file changed, 1 insertion(+), 19 deletions(-) (limited to 'kernel') diff --git a/kernel/sys.c b/kernel/sys.c index 304b5410d746..d1fe71eb4546 100644 --- a/kernel/sys.c +++ b/kernel/sys.c @@ -1750,7 +1750,7 @@ asmlinkage long sys_prctl(int option, unsigned long arg2, unsigned long arg3, } asmlinkage long sys_getcpu(unsigned __user *cpup, unsigned __user *nodep, - struct getcpu_cache __user *cache) + struct getcpu_cache __user *unused) { int err = 0; int cpu = raw_smp_processor_id(); @@ -1758,24 +1758,6 @@ asmlinkage long sys_getcpu(unsigned __user *cpup, unsigned __user *nodep, err |= put_user(cpu, cpup); if (nodep) err |= put_user(cpu_to_node(cpu), nodep); - if (cache) { - /* - * The cache is not needed for this implementation, - * but make sure user programs pass something - * valid. vsyscall implementations can instead make - * good use of the cache. Only use t0 and t1 because - * these are available in both 32bit and 64bit ABI (no - * need for a compat_getcpu). 32bit has enough - * padding - */ - unsigned long t0, t1; - get_user(t0, &cache->blob[0]); - get_user(t1, &cache->blob[1]); - t0++; - t1++; - put_user(t0, &cache->blob[0]); - put_user(t1, &cache->blob[1]); - } return err ? -EFAULT : 0; } -- cgit v1.2.3 From fa6a1a554b50cbb7763f6907e6fef927ead480d9 Mon Sep 17 00:00:00 2001 From: "David P. Reed" Date: Wed, 14 Nov 2007 17:49:21 -0500 Subject: ntp: fix typo that makes sync_cmos_clock erratic Fix a typo in ntp.c that has caused updating of the persistent (RTC) clock when synced to NTP to behave erratically. When debugging a freeze that arises on my AMD64 machines when I run the ntpd service, I added a number of printk's to monitor the sync_cmos_clock procedure. I discovered that it was not syncing to cmos RTC every 11 minutes as documented, but instead would keep trying every second for hours at a time. The reason turned out to be a typo in sync_cmos_clock, where it attempts to ensure that update_persistent_clock is called very close to 500 msec. after a 1 second boundary (required by the PC RTC's spec). That typo referred to "xtime" in one spot, rather than "now", which is derived from "xtime" but not equal to it. This makes the test erratic, creating a "coin-flip" that decides when update_persistent_clock is called - when it is called, which is rarely, it may be at any time during the one second period, rather than close to 500 msec, so the value written is needlessly incorrect, too. Signed-off-by: David P. Reed Signed-off-by: Thomas Gleixner --- kernel/time/ntp.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'kernel') diff --git a/kernel/time/ntp.c b/kernel/time/ntp.c index de6a2d6b3ebb..14a2ecf2b318 100644 --- a/kernel/time/ntp.c +++ b/kernel/time/ntp.c @@ -205,7 +205,7 @@ static void sync_cmos_clock(unsigned long dummy) return; getnstimeofday(&now); - if (abs(xtime.tv_nsec - (NSEC_PER_SEC / 2)) <= tick_nsec / 2) + if (abs(now.tv_nsec - (NSEC_PER_SEC / 2)) <= tick_nsec / 2) fail = update_persistent_clock(now); next.tv_nsec = (NSEC_PER_SEC / 2) - now.tv_nsec; -- cgit v1.2.3