From: Zhouyi Zhou <zhouzhouyi@gmail.com>
Date: Mon, 11 Jan 2021 01:08:59 +0000 (+0800)
Subject: rcu: Remove spurious instrumentation_end() in rcu_nmi_enter()
X-Git-Tag: v5.11.21~286
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=6d79181f4e28ce9f058247dc5e18b1b5f1b74c83;p=thirdparty%2Fkernel%2Fstable.git

rcu: Remove spurious instrumentation_end() in rcu_nmi_enter()

[ Upstream commit 6494ccb93271bee596a12db32ff44867d5be2321 ]

In rcu_nmi_enter(), there is an erroneous instrumentation_end() in the
second branch of the "if" statement.  Oddly enough, "objtool check -f
vmlinux.o" fails to complain because it is unable to correctly cover
all cases.  Instead, objtool visits the third branch first, which marks
following trace_rcu_dyntick() as visited.  This commit therefore removes
the spurious instrumentation_end().

Fixes: 04b25a495bd6 ("rcu: Mark rcu_nmi_enter() call to rcu_cleanup_after_idle() noinstr")
Reported-by Neeraj Upadhyay <neeraju@codeaurora.org>
Signed-off-by: Zhouyi Zhou <zhouzhouyi@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---

diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 84a3fe09630b3..e7d8a0d8ea7cc 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -1072,7 +1072,6 @@ noinstr void rcu_nmi_enter(void)
 	} else if (!in_nmi()) {
 		instrumentation_begin();
 		rcu_irq_enter_check_tick();
-		instrumentation_end();
 	} else  {
 		instrumentation_begin();
 	}