From: Yunfeng Ye yeyunfeng@huawei.com
mainline inclusion from mainline-5.11-rc1 commit 896b969e6732b68ee3c12ae4e1aeddf5db99bc46 category: feature feature: Deep isolation bugzilla: https://gitee.com/openeuler/kernel/issues/I4N00D CVE: NA
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...
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calc_load_global() does not need the sequence count protection.
[ tglx: Split it up properly and added comments ]
Signed-off-by: Yunfeng Ye yeyunfeng@huawei.com Signed-off-by: Thomas Gleixner tglx@linutronix.de Link: https://lore.kernel.org/r/20201117132006.660902274@linutronix.de Reviewed-by: Chao Liu liuchao173@huawei.com Reviewed-by: Chen Hui judy.chenhui@huawei.com Acked-by: Xie XiuQi xiexiuqi@huawei.com Signed-off-by: Zheng Zengkai zhengzengkai@huawei.com --- kernel/time/tick-sched.c | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-)
diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c index 2b1eb5038a1f..651545679c3e 100644 --- a/kernel/time/tick-sched.c +++ b/kernel/time/tick-sched.c @@ -20,6 +20,7 @@ #include <linux/sched/clock.h> #include <linux/sched/stat.h> #include <linux/sched/nohz.h> +#include <linux/sched/loadavg.h> #include <linux/module.h> #include <linux/irq_work.h> #include <linux/posix-timers.h> @@ -105,7 +106,8 @@ static void tick_do_update_jiffies64(ktime_t now) tick_period); }
- do_timer(ticks); + /* Advance jiffies to complete the jiffies_seq protected job */ + jiffies_64 += ticks;
/* * Keep the tick_next_period variable up to date. WRITE_ONCE() @@ -114,7 +116,15 @@ static void tick_do_update_jiffies64(ktime_t now) WRITE_ONCE(tick_next_period, ktime_add(last_jiffies_update, tick_period));
+ /* + * Release the sequence count. calc_global_load() below is not + * protected by it, but jiffies_lock needs to be held to prevent + * concurrent invocations. + */ write_seqcount_end(&jiffies_seq); + + calc_global_load(); + raw_spin_unlock(&jiffies_lock); update_wall_time(); }