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[Qemu-devel] [PATCH 4/8] rcu: allow nesting of rcu_read_lock/rcu_read_un
From: |
Paolo Bonzini |
Subject: |
[Qemu-devel] [PATCH 4/8] rcu: allow nesting of rcu_read_lock/rcu_read_unlock |
Date: |
Tue, 13 Jan 2015 18:52:13 +0100 |
Signed-off-by: Paolo Bonzini <address@hidden>
---
include/qemu/rcu.h | 15 ++++++++++++++-
tests/rcutorture.c | 2 ++
2 files changed, 16 insertions(+), 1 deletion(-)
diff --git a/include/qemu/rcu.h b/include/qemu/rcu.h
index 91b3a5c..e3d9b63 100644
--- a/include/qemu/rcu.h
+++ b/include/qemu/rcu.h
@@ -76,6 +76,9 @@ struct rcu_reader_data {
unsigned long ctr;
bool waiting;
+ /* Data used by reader only */
+ unsigned depth;
+
/* Data used for registry, protected by rcu_gp_lock */
QLIST_ENTRY(rcu_reader_data) node;
};
@@ -85,8 +88,13 @@ extern __thread struct rcu_reader_data rcu_reader;
static inline void rcu_read_lock(void)
{
struct rcu_reader_data *p_rcu_reader = &rcu_reader;
+ unsigned ctr;
+
+ if (p_rcu_reader->depth++ > 0) {
+ return;
+ }
- unsigned ctr = atomic_read(&rcu_gp_ctr);
+ ctr = atomic_read(&rcu_gp_ctr);
atomic_xchg(&p_rcu_reader->ctr, ctr);
if (atomic_read(&p_rcu_reader->waiting)) {
atomic_set(&p_rcu_reader->waiting, false);
@@ -98,6 +106,11 @@ static inline void rcu_read_unlock(void)
{
struct rcu_reader_data *p_rcu_reader = &rcu_reader;
+ assert(p_rcu_reader->depth != 0);
+ if (--p_rcu_reader->depth > 0) {
+ return;
+ }
+
atomic_xchg(&p_rcu_reader->ctr, 0);
if (atomic_read(&p_rcu_reader->waiting)) {
atomic_set(&p_rcu_reader->waiting, false);
diff --git a/tests/rcutorture.c b/tests/rcutorture.c
index cda7458..a6ac2a9 100644
--- a/tests/rcutorture.c
+++ b/tests/rcutorture.c
@@ -257,9 +257,11 @@ static void *rcu_read_stress_test(void *arg)
if (p->mbtest == 0) {
n_mberror++;
}
+ rcu_read_lock();
for (i = 0; i < 100; i++) {
garbage++;
}
+ rcu_read_unlock();
pc = p->pipe_count;
rcu_read_unlock();
if ((pc > RCU_STRESS_PIPE_LEN) || (pc < 0)) {
--
1.8.3.1
- [Qemu-devel] [PATCH 2/8] rcu: add rcu library, (continued)
- [Qemu-devel] [PATCH 2/8] rcu: add rcu library, Paolo Bonzini, 2015/01/13
- [Qemu-devel] [PATCH 6/8] memory: remove assertion on memory_region_destroy, Paolo Bonzini, 2015/01/13
- [Qemu-devel] [PATCH 5/8] rcu: add call_rcu, Paolo Bonzini, 2015/01/13
- [Qemu-devel] [PATCH 3/8] rcu: add rcutorture, Paolo Bonzini, 2015/01/13
- [Qemu-devel] [PATCH 7/8] memory: protect current_map by RCU, Paolo Bonzini, 2015/01/13
- [Qemu-devel] [PATCH 8/8] memory: avoid ref/unref in memory_region_find, Paolo Bonzini, 2015/01/13
- [Qemu-devel] [PATCH 4/8] rcu: allow nesting of rcu_read_lock/rcu_read_unlock,
Paolo Bonzini <=
- Re: [Qemu-devel] [PATCH 0/8] RCUification of the memory API, part 1, Christian Borntraeger, 2015/01/16