From 3d12fd7aa1a00dedbf27081df39b13385fdc7bbf Mon Sep 17 00:00:00 2001 From: Yunfeng Ye Date: Wed, 29 Dec 2021 12:12:57 +0800 Subject: [PATCH] tick/sched: Release seqcount before invoking calc_load_global() 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/?id=896b969e6732b68ee3c12ae4e1aeddf5db99bc46 -------------------------------- calc_load_global() does not need the sequence count protection. [ tglx: Split it up properly and added comments ] Signed-off-by: Yunfeng Ye Signed-off-by: Thomas Gleixner Link: https://lore.kernel.org/r/20201117132006.660902274@linutronix.de Reviewed-by: Chao Liu Reviewed-by: Chen Hui Acked-by: Xie XiuQi Signed-off-by: Zheng Zengkai --- 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 #include #include +#include #include #include #include @@ -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(); } -- GitLab