This commit makes DEFINE_SRCU_FAST() available to modules. The trick
is that DEFINE_SRCU_FAST() does not allocate the per-CPU data structure
when used within a module (by design), which means that it is not possible
to compile-time-initialize any of the fields in this structure, including
in particular the ->srcu_reader_flavor field.
This commit therefore creates an ->srcu_reader_flavor field in the
srcu_struct structure, adds arguments to the DEFINE_SRCU()-related
macros to initialize this new field, and extending the checks in the
__srcu_check_read_flavor() function to include this new field.
Signed-off-by: Paul E. McKenney <paul...@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoy...@efficios.com>
Cc: Steven Rostedt <rost...@goodmis.org>
Cc: Sebastian Andrzej Siewior <bige...@linutronix.de>
Cc: <b...@vger.kernel.org>
---
include/linux/notifier.h | 2 +-
include/linux/srcutiny.h | 10 ++++++----
include/linux/srcutree.h | 24 +++++++++++++-----------
kernel/rcu/srcutree.c | 3 +++
4 files changed, 23 insertions(+), 16 deletions(-)
diff --git a/include/linux/notifier.h b/include/linux/notifier.h
index b42e6473496882..01b6c9d9956f90 100644
--- a/include/linux/notifier.h
+++ b/include/linux/notifier.h
@@ -109,7 +109,7 @@ extern void srcu_init_notifier_head(struct
srcu_notifier_head *nh);
.mutex = __MUTEX_INITIALIZER(name.mutex), \
.head = NULL, \
.srcuu = __SRCU_USAGE_INIT(name.srcuu), \
- .srcu = __SRCU_STRUCT_INIT(name.srcu, name.srcuu, pcpu), \
+ .srcu = __SRCU_STRUCT_INIT(name.srcu, name.srcuu, pcpu, 0), \
}
#define ATOMIC_NOTIFIER_HEAD(name) \
diff --git a/include/linux/srcutiny.h b/include/linux/srcutiny.h
index 941e8210479607..b5f62259d56fb1 100644
--- a/include/linux/srcutiny.h
+++ b/include/linux/srcutiny.h
@@ -31,7 +31,7 @@ struct srcu_struct {
void srcu_drive_gp(struct work_struct *wp);
-#define __SRCU_STRUCT_INIT(name, __ignored, ___ignored)
\
+#define __SRCU_STRUCT_INIT(name, __ignored, ___ignored, ____ignored) \
{ \
.srcu_wq = __SWAIT_QUEUE_HEAD_INITIALIZER(name.srcu_wq), \
.srcu_cb_tail = &name.srcu_cb_head, \
@@ -44,10 +44,12 @@ void srcu_drive_gp(struct work_struct *wp);
* Tree SRCU, which needs some per-CPU data.
*/
#define DEFINE_SRCU(name) \
- struct srcu_struct name = __SRCU_STRUCT_INIT(name, name, name)
-#define DEFINE_SRCU_FAST(name) DEFINE_SRCU(name)
+ struct srcu_struct name = __SRCU_STRUCT_INIT(name, name, name, name)
#define DEFINE_STATIC_SRCU(name) \
- static struct srcu_struct name = __SRCU_STRUCT_INIT(name, name, name)
+ static struct srcu_struct name = __SRCU_STRUCT_INIT(name, name, name,
name)
+#define DEFINE_SRCU_FAST(name) DEFINE_SRCU(name)
+#define DEFINE_STATIC_SRCU_FAST(name) \
+ static struct srcu_struct name = __SRCU_STRUCT_INIT(name, name, name,
name)
// Dummy structure for srcu_notifier_head.
struct srcu_usage { };
diff --git a/include/linux/srcutree.h b/include/linux/srcutree.h
index 4a5d1c0e7db361..05400f70baa40a 100644
--- a/include/linux/srcutree.h
+++ b/include/linux/srcutree.h
@@ -104,6 +104,7 @@ struct srcu_usage {
struct srcu_struct {
struct srcu_ctr __percpu *srcu_ctrp;
struct srcu_data __percpu *sda; /* Per-CPU srcu_data array. */
+ u8 srcu_reader_flavor;
struct lockdep_map dep_map;
struct srcu_usage *srcu_sup; /* Update-side data. */
};
@@ -162,20 +163,21 @@ struct srcu_struct {
.work = __DELAYED_WORK_INITIALIZER(name.work, NULL, 0),
\
}
-#define __SRCU_STRUCT_INIT_COMMON(name, usage_name)
\
+#define __SRCU_STRUCT_INIT_COMMON(name, usage_name, fast)
\
.srcu_sup = &usage_name,
\
+ .srcu_reader_flavor = fast,
\
__SRCU_DEP_MAP_INIT(name)
-#define __SRCU_STRUCT_INIT_MODULE(name, usage_name)
\
+#define __SRCU_STRUCT_INIT_MODULE(name, usage_name, fast)
\
{
\
- __SRCU_STRUCT_INIT_COMMON(name, usage_name)
\
+ __SRCU_STRUCT_INIT_COMMON(name, usage_name, fast)
\
}
-#define __SRCU_STRUCT_INIT(name, usage_name, pcpu_name)
\
+#define __SRCU_STRUCT_INIT(name, usage_name, pcpu_name, fast)
\
{
\
.sda = &pcpu_name,
\
.srcu_ctrp = &pcpu_name.srcu_ctrs[0],
\
- __SRCU_STRUCT_INIT_COMMON(name, usage_name)
\
+ __SRCU_STRUCT_INIT_COMMON(name, usage_name, fast)
\
}
/*
@@ -207,22 +209,22 @@ struct srcu_struct {
#ifdef MODULE
# define __DEFINE_SRCU(name, fast, is_static)
\
static struct srcu_usage name##_srcu_usage =
__SRCU_USAGE_INIT(name##_srcu_usage); \
- is_static struct srcu_struct name = __SRCU_STRUCT_INIT_MODULE(name,
name##_srcu_usage); \
+ is_static struct srcu_struct name = __SRCU_STRUCT_INIT_MODULE(name,
name##_srcu_usage, \
+ fast);
\
extern struct srcu_struct * const __srcu_struct_##name;
\
struct srcu_struct * const __srcu_struct_##name
\
__section("___srcu_struct_ptrs") = &name
#else
# define __DEFINE_SRCU(name, fast, is_static)
\
- static DEFINE_PER_CPU(struct srcu_data, name##_srcu_data) = {
\
- .srcu_reader_flavor = fast,
\
- };
\
+ static DEFINE_PER_CPU(struct srcu_data, name##_srcu_data);
\
static struct srcu_usage name##_srcu_usage =
__SRCU_USAGE_INIT(name##_srcu_usage); \
is_static struct srcu_struct name =
\
- __SRCU_STRUCT_INIT(name, name##_srcu_usage, name##_srcu_data)
-#define DEFINE_SRCU_FAST(name) __DEFINE_SRCU(name,
SRCU_READ_FLAVOR_FAST, /* not static */)
+ __SRCU_STRUCT_INIT(name, name##_srcu_usage, name##_srcu_data,
fast)
#endif
#define DEFINE_SRCU(name) __DEFINE_SRCU(name, 0, /* not static */)
#define DEFINE_STATIC_SRCU(name) __DEFINE_SRCU(name, 0, static)
+#define DEFINE_SRCU_FAST(name) __DEFINE_SRCU(name,
SRCU_READ_FLAVOR_FAST, /* not static */)
+#define DEFINE_STATIC_SRCU_FAST(name) __DEFINE_SRCU(name,
SRCU_READ_FLAVOR_FAST, static)
int __srcu_read_lock(struct srcu_struct *ssp) __acquires(ssp);
void synchronize_srcu_expedited(struct srcu_struct *ssp);
diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c
index f2f11492e6936e..7c8b39d4dd3162 100644
--- a/kernel/rcu/srcutree.c
+++ b/kernel/rcu/srcutree.c
@@ -734,6 +734,9 @@ void __srcu_check_read_flavor(struct srcu_struct *ssp, int
read_flavor)
sdp = raw_cpu_ptr(ssp->sda);
old_read_flavor = READ_ONCE(sdp->srcu_reader_flavor);
+ WARN_ON_ONCE(ssp->srcu_reader_flavor && read_flavor !=
ssp->srcu_reader_flavor);
+ WARN_ON_ONCE(old_read_flavor && ssp->srcu_reader_flavor &&
+ old_read_flavor != ssp->srcu_reader_flavor);
if (!old_read_flavor) {
old_read_flavor = cmpxchg(&sdp->srcu_reader_flavor, 0,
read_flavor);
if (!old_read_flavor)
--
2.40.1
