From: "Paul E. McKenney" <paulmck@kernel.org>
To: rcu@vger.kernel.org
Cc: linux-kernel@vger.kernel.org, kernel-team@fb.com,
mingo@kernel.org, jiangshanlai@gmail.com,
akpm@linux-foundation.org, mathieu.desnoyers@efficios.com,
josh@joshtriplett.org, tglx@linutronix.de, peterz@infradead.org,
rostedt@goodmis.org, dhowells@redhat.com, edumazet@google.com,
fweisbec@gmail.com, oleg@redhat.com, joel@joelfernandes.org,
Frederic Weisbecker <frederic@kernel.org>,
Uladzislau Rezki <urezki@gmail.com>,
Boqun Feng <boqun.feng@gmail.com>,
Neeraj Upadhyay <neeraju@codeaurora.org>,
"Paul E . McKenney" <paulmck@kernel.org>
Subject: [PATCH tip/core/rcu 4/6] srcu: Initialize SRCU after timers
Date: Tue, 11 May 2021 16:07:43 -0700 [thread overview]
Message-ID: <20210511230745.2894650-4-paulmck@kernel.org> (raw)
In-Reply-To: <20210511230720.GA2894512@paulmck-ThinkPad-P17-Gen-1>
From: Frederic Weisbecker <frederic@kernel.org>
Once srcu_init() is called, the SRCU core will make use of delayed
workqueues, which rely on timers. However init_timers() is called
several steps after rcu_init(). This means that a call_srcu() after
rcu_init() but before init_timers() would find itself within a dangerously
uninitialized timer core.
This commit therefore creates a separate call to srcu_init() after
init_timer() completes, which ensures that we stay in early SRCU mode
until timers are safe(r).
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Cc: Uladzislau Rezki <urezki@gmail.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Neeraj Upadhyay <neeraju@codeaurora.org>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Joel Fernandes <joel@joelfernandes.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
---
include/linux/srcu.h | 6 ++++++
init/main.c | 2 ++
kernel/rcu/rcu.h | 6 ------
kernel/rcu/srcutree.c | 5 +++++
kernel/rcu/tiny.c | 1 -
kernel/rcu/tree.c | 1 -
6 files changed, 13 insertions(+), 8 deletions(-)
diff --git a/include/linux/srcu.h b/include/linux/srcu.h
index a0895bbf71ce..e6011a9975af 100644
--- a/include/linux/srcu.h
+++ b/include/linux/srcu.h
@@ -64,6 +64,12 @@ unsigned long get_state_synchronize_srcu(struct srcu_struct *ssp);
unsigned long start_poll_synchronize_srcu(struct srcu_struct *ssp);
bool poll_state_synchronize_srcu(struct srcu_struct *ssp, unsigned long cookie);
+#ifdef CONFIG_SRCU
+void srcu_init(void);
+#else /* #ifdef CONFIG_SRCU */
+static inline void srcu_init(void) { }
+#endif /* #else #ifdef CONFIG_SRCU */
+
#ifdef CONFIG_DEBUG_LOCK_ALLOC
/**
diff --git a/init/main.c b/init/main.c
index eb01e121d2f1..7b6f49c4d388 100644
--- a/init/main.c
+++ b/init/main.c
@@ -42,6 +42,7 @@
#include <linux/profile.h>
#include <linux/kfence.h>
#include <linux/rcupdate.h>
+#include <linux/srcu.h>
#include <linux/moduleparam.h>
#include <linux/kallsyms.h>
#include <linux/writeback.h>
@@ -979,6 +980,7 @@ asmlinkage __visible void __init __no_sanitize_address start_kernel(void)
tick_init();
rcu_init_nohz();
init_timers();
+ srcu_init();
hrtimers_init();
softirq_init();
timekeeping_init();
diff --git a/kernel/rcu/rcu.h b/kernel/rcu/rcu.h
index bf0827d4b659..ca3f2af32bf8 100644
--- a/kernel/rcu/rcu.h
+++ b/kernel/rcu/rcu.h
@@ -422,12 +422,6 @@ do { \
#endif /* #if defined(CONFIG_SRCU) || !defined(CONFIG_TINY_RCU) */
-#ifdef CONFIG_SRCU
-void srcu_init(void);
-#else /* #ifdef CONFIG_SRCU */
-static inline void srcu_init(void) { }
-#endif /* #else #ifdef CONFIG_SRCU */
-
#ifdef CONFIG_TINY_RCU
/* Tiny RCU doesn't expedite, as its purpose in life is instead to be tiny. */
static inline bool rcu_gp_is_normal(void) { return true; }
diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c
index f4f0cbf7a02b..9ec35c158740 100644
--- a/kernel/rcu/srcutree.c
+++ b/kernel/rcu/srcutree.c
@@ -1384,6 +1384,11 @@ void __init srcu_init(void)
{
struct srcu_struct *ssp;
+ /*
+ * Once that is set, call_srcu() can follow the normal path and
+ * queue delayed work. This must follow RCU workqueues creation
+ * and timers initialization.
+ */
srcu_init_done = true;
while (!list_empty(&srcu_boot_list)) {
ssp = list_first_entry(&srcu_boot_list, struct srcu_struct,
diff --git a/kernel/rcu/tiny.c b/kernel/rcu/tiny.c
index c8a029fbb114..340b3f8b090d 100644
--- a/kernel/rcu/tiny.c
+++ b/kernel/rcu/tiny.c
@@ -221,5 +221,4 @@ void __init rcu_init(void)
{
open_softirq(RCU_SOFTIRQ, rcu_process_callbacks);
rcu_early_boot_tests();
- srcu_init();
}
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 8e78b2430c16..c35b15229cff 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -4735,7 +4735,6 @@ void __init rcu_init(void)
WARN_ON(!rcu_gp_wq);
rcu_par_gp_wq = alloc_workqueue("rcu_par_gp", WQ_MEM_RECLAIM, 0);
WARN_ON(!rcu_par_gp_wq);
- srcu_init();
/* Fill in default value for rcutree.qovld boot parameter. */
/* -After- the rcu_node ->lock fields are initialized! */
--
2.31.1.189.g2e36527f23
next prev parent reply other threads:[~2021-05-11 23:07 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-11 23:07 [PATCH tip/core/rcu 0/6] SRCU updates for v5.14 Paul E. McKenney
2021-05-11 23:07 ` [PATCH tip/core/rcu 1/6] srcu: Remove superfluous sdp->srcu_lock_count zero filling Paul E. McKenney
2021-05-11 23:07 ` [PATCH tip/core/rcu 2/6] srcu: Remove superfluous ssp initialization for early callbacks Paul E. McKenney
2021-05-11 23:07 ` [PATCH tip/core/rcu 3/6] srcu: Unconditionally embed struct lockdep_map Paul E. McKenney
2021-05-11 23:07 ` Paul E. McKenney [this message]
2021-05-11 23:07 ` [PATCH tip/core/rcu 5/6] srcu: Fix broken node geometry after early ssp init Paul E. McKenney
2021-05-11 23:07 ` [PATCH tip/core/rcu 6/6] srcu: Early test SRCU polling start Paul E. McKenney
2021-05-11 23:09 ` [PATCH tip/core/rcu 1/4] rcu-tasks: Add block comment laying out RCU Tasks design Paul E. McKenney
2021-05-11 23:09 ` [PATCH tip/core/rcu 2/4] rcu-tasks: Add block comment laying out RCU Rude design Paul E. McKenney
2021-05-11 23:09 ` [PATCH tip/core/rcu 3/4] rcu-tasks: Make ksoftirqd provide RCU Tasks quiescent states Paul E. McKenney
2021-05-11 23:09 ` [PATCH tip/core/rcu 4/4] tasks-rcu: Make show_rcu_tasks_gp_kthreads() be static inline Paul E. McKenney
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