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Message-Id: <20230724022651.899-2-thunder.leizhen@huaweicloud.com>
Date: Mon, 24 Jul 2023 10:26:51 +0800
From: thunder.leizhen@...weicloud.com
To: "Paul E . McKenney" <paulmck@...nel.org>,
Frederic Weisbecker <frederic@...nel.org>,
Neeraj Upadhyay <quic_neeraju@...cinc.com>,
Joel Fernandes <joel@...lfernandes.org>,
Josh Triplett <josh@...htriplett.org>,
Boqun Feng <boqun.feng@...il.com>,
Steven Rostedt <rostedt@...dmis.org>,
Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
Lai Jiangshan <jiangshanlai@...il.com>,
Zqiang <qiang.zhang1211@...il.com>, rcu@...r.kernel.org,
linux-kernel@...r.kernel.org
Cc: Zhen Lei <thunder.leizhen@...wei.com>
Subject: [PATCH v2 1/1] rcu: Simplify check_cpu_stall()
From: Zhen Lei <thunder.leizhen@...wei.com>
The code and comments of self detected and other detected are the same
except the output function. Combine the same parts to avoid duplication.
Signed-off-by: Zhen Lei <thunder.leizhen@...wei.com>
---
kernel/rcu/tree_stall.h | 42 +++++++++++++++--------------------------
1 file changed, 15 insertions(+), 27 deletions(-)
diff --git a/kernel/rcu/tree_stall.h b/kernel/rcu/tree_stall.h
index cc884cd49e026a3..b45d7e49944cdd7 100644
--- a/kernel/rcu/tree_stall.h
+++ b/kernel/rcu/tree_stall.h
@@ -711,7 +711,7 @@ static void print_cpu_stall(unsigned long gps)
static void check_cpu_stall(struct rcu_data *rdp)
{
- bool didstall = false;
+ bool self_detected;
unsigned long gs1;
unsigned long gs2;
unsigned long gps;
@@ -758,10 +758,10 @@ static void check_cpu_stall(struct rcu_data *rdp)
return; /* No stall or GP completed since entering function. */
rnp = rdp->mynode;
jn = jiffies + ULONG_MAX / 2;
+ self_detected = READ_ONCE(rnp->qsmask) & rdp->grpmask;
if (rcu_gp_in_progress() &&
- (READ_ONCE(rnp->qsmask) & rdp->grpmask) &&
+ (self_detected || ULONG_CMP_GE(j, js + RCU_STALL_RAT_DELAY)) &&
cmpxchg(&rcu_state.jiffies_stall, js, jn) == js) {
-
/*
* If a virtual machine is stopped by the host it can look to
* the watchdog like an RCU stall. Check to see if the host
@@ -770,33 +770,21 @@ static void check_cpu_stall(struct rcu_data *rdp)
if (kvm_check_and_clear_guest_paused())
return;
- /* We haven't checked in, so go dump stack. */
- print_cpu_stall(gps);
- if (READ_ONCE(rcu_cpu_stall_ftrace_dump))
- rcu_ftrace_dump(DUMP_ALL);
- didstall = true;
-
- } else if (rcu_gp_in_progress() &&
- ULONG_CMP_GE(j, js + RCU_STALL_RAT_DELAY) &&
- cmpxchg(&rcu_state.jiffies_stall, js, jn) == js) {
-
- /*
- * If a virtual machine is stopped by the host it can look to
- * the watchdog like an RCU stall. Check to see if the host
- * stopped the vm.
- */
- if (kvm_check_and_clear_guest_paused())
- return;
+ if (self_detected) {
+ /* We haven't checked in, so go dump stack. */
+ print_cpu_stall(gps);
+ } else {
+ /* They had a few time units to dump stack, so complain. */
+ print_other_cpu_stall(gs2, gps);
+ }
- /* They had a few time units to dump stack, so complain. */
- print_other_cpu_stall(gs2, gps);
if (READ_ONCE(rcu_cpu_stall_ftrace_dump))
rcu_ftrace_dump(DUMP_ALL);
- didstall = true;
- }
- if (didstall && READ_ONCE(rcu_state.jiffies_stall) == jn) {
- jn = jiffies + 3 * rcu_jiffies_till_stall_check() + 3;
- WRITE_ONCE(rcu_state.jiffies_stall, jn);
+
+ if (READ_ONCE(rcu_state.jiffies_stall) == jn) {
+ jn = jiffies + 3 * rcu_jiffies_till_stall_check() + 3;
+ WRITE_ONCE(rcu_state.jiffies_stall, jn);
+ }
}
}
--
2.25.1
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