lkml.org 
[lkml]   [2017]   [Apr]   [12]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH tip/core/rcu 25/40] srcu: Add grace-period sequence numbers
Date
This commit adds grace-period sequence numbers, which will be used to
handle mid-boot grace periods and per-CPU callback lists.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
---
include/linux/srcu.h | 1 +
kernel/rcu/srcu.c | 27 +++++++++++++++++++++++----
2 files changed, 24 insertions(+), 4 deletions(-)

diff --git a/include/linux/srcu.h b/include/linux/srcu.h
index f149a685896c..047ac8c28a4e 100644
--- a/include/linux/srcu.h
+++ b/include/linux/srcu.h
@@ -46,6 +46,7 @@ struct rcu_batch {

struct srcu_struct {
unsigned long completed;
+ unsigned long srcu_gp_seq;
struct srcu_array __percpu *per_cpu_ref;
spinlock_t queue_lock; /* protect ->batch_queue, ->running */
int srcu_state;
diff --git a/kernel/rcu/srcu.c b/kernel/rcu/srcu.c
index 84da09c02971..ed7c3d082b9f 100644
--- a/kernel/rcu/srcu.c
+++ b/kernel/rcu/srcu.c
@@ -110,6 +110,7 @@ static inline void rcu_batch_move(struct rcu_batch *to, struct rcu_batch *from)
static int init_srcu_struct_fields(struct srcu_struct *sp)
{
sp->completed = 0;
+ sp->srcu_gp_seq = 0;
spin_lock_init(&sp->queue_lock);
sp->srcu_state = SRCU_STATE_IDLE;
rcu_batch_init(&sp->batch_queue);
@@ -313,6 +314,15 @@ EXPORT_SYMBOL_GPL(__srcu_read_unlock);
#define SYNCHRONIZE_SRCU_EXP_TRYCOUNT 12

/*
+ * Start an SRCU grace period.
+ */
+static void srcu_gp_start(struct srcu_struct *sp)
+{
+ WRITE_ONCE(sp->srcu_state, SRCU_STATE_SCAN1);
+ rcu_seq_start(&sp->srcu_gp_seq);
+}
+
+/*
* @@@ Wait until all pre-existing readers complete. Such readers
* will have used the index specified by "idx".
* the caller should ensures the ->completed is not changed while checking
@@ -349,6 +359,15 @@ static void srcu_flip(struct srcu_struct *sp)
}

/*
+ * End an SRCU grace period.
+ */
+static void srcu_gp_end(struct srcu_struct *sp)
+{
+ rcu_seq_end(&sp->srcu_gp_seq);
+ WRITE_ONCE(sp->srcu_state, SRCU_STATE_DONE);
+}
+
+/*
* Enqueue an SRCU callback on the specified srcu_struct structure,
* initiating grace-period processing if it is not already running.
*
@@ -386,7 +405,7 @@ void call_srcu(struct srcu_struct *sp, struct rcu_head *head,
smp_mb__after_unlock_lock(); /* Caller's prior accesses before GP. */
rcu_batch_queue(&sp->batch_queue, head);
if (READ_ONCE(sp->srcu_state) == SRCU_STATE_IDLE) {
- WRITE_ONCE(sp->srcu_state, SRCU_STATE_SCAN1);
+ srcu_gp_start(sp);
queue_delayed_work(system_power_efficient_wq, &sp->work, 0);
}
spin_unlock_irqrestore(&sp->queue_lock, flags);
@@ -420,7 +439,7 @@ static void __synchronize_srcu(struct srcu_struct *sp, int trycount)
smp_mb__after_unlock_lock(); /* Caller's prior accesses before GP. */
if (READ_ONCE(sp->srcu_state) == SRCU_STATE_IDLE) {
/* steal the processing owner */
- WRITE_ONCE(sp->srcu_state, SRCU_STATE_SCAN1);
+ srcu_gp_start(sp);
rcu_batch_queue(&sp->batch_check0, head);
spin_unlock_irq(&sp->queue_lock);
/* give the processing owner to work_struct */
@@ -555,7 +574,7 @@ static void srcu_advance_batches(struct srcu_struct *sp, int trycount)
*/

if (sp->srcu_state == SRCU_STATE_DONE)
- WRITE_ONCE(sp->srcu_state, SRCU_STATE_SCAN1);
+ srcu_gp_start(sp);

if (sp->srcu_state == SRCU_STATE_SCAN1) {
idx = 1 ^ (sp->completed & 1);
@@ -602,7 +621,7 @@ static void srcu_advance_batches(struct srcu_struct *sp, int trycount)
*/
rcu_batch_move(&sp->batch_done, &sp->batch_check1);

- WRITE_ONCE(sp->srcu_state, SRCU_STATE_DONE);
+ srcu_gp_end(sp);
}
}

--
2.5.2
\
 
 \ /
  Last update: 2017-04-12 19:48    [W:0.547 / U:1.520 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site