entry: Explicitly flush pending rcuog wakeup before last rescheduling point

mainline inclusion
from mainline-v5.12-rc1
commit 47b8ff19
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I4U05V


CVE: NA

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Following the idle loop model, cleanly check for pending rcuog wakeup
before the last rescheduling point on resuming to user mode. This
way we can avoid to do it from rcu_user_enter() with the last resort
self-IPI hack that enforces rescheduling.

Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/20210131230548.32970-5-frederic@kernel.org


Conflicts:
	kernel/entry/common.c

Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
Reviewed-by: Cheng Jian <cj.chengjian@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>