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authorMaarten Lankhorst <maarten.lankhorst@canonical.com>2014-07-01 12:58:00 +0200
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2014-07-08 13:41:08 -0700
commit3c3b177a9369b26890ced004867fb32708e8ef5b (patch)
treed7f1840cd62b8c0d427ea56b203485c2e27bb29e /include/linux/reservation.h
parent04a5faa8cbe5a8eaf152cb88959ba6360c26e702 (diff)
reservation: add suppport for read-only access using rcu
This adds some extra functions to deal with rcu. reservation_object_get_fences_rcu() will obtain the list of shared and exclusive fences without obtaining the ww_mutex. reservation_object_wait_timeout_rcu() will wait on all fences of the reservation_object, without obtaining the ww_mutex. reservation_object_test_signaled_rcu() will test if all fences of the reservation_object are signaled without using the ww_mutex. reservation_object_get_excl and reservation_object_get_list require the reservation object to be held, updating requires write_seqcount_begin/end. If only the exclusive fence is needed, rcu_dereference followed by fence_get_rcu can be used, if the shared fences are needed it's recommended to use the supplied functions. Signed-off-by: Maarten Lankhorst <maarten.lankhorst@canonical.com> Acked-by: Sumit Semwal <sumit.semwal@linaro.org> Acked-by: Daniel Vetter <daniel@ffwll.ch> Reviewed-By: Thomas Hellstrom <thellstrom@vmware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'include/linux/reservation.h')
-rw-r--r--include/linux/reservation.h52
1 files changed, 36 insertions, 16 deletions
diff --git a/include/linux/reservation.h b/include/linux/reservation.h
index 2affe67dea6e..5a0b64cf68b4 100644
--- a/include/linux/reservation.h
+++ b/include/linux/reservation.h
@@ -42,22 +42,29 @@
#include <linux/ww_mutex.h>
#include <linux/fence.h>
#include <linux/slab.h>
+#include <linux/seqlock.h>
+#include <linux/rcupdate.h>
extern struct ww_class reservation_ww_class;
+extern struct lock_class_key reservation_seqcount_class;
+extern const char reservation_seqcount_string[];
struct reservation_object_list {
+ struct rcu_head rcu;
u32 shared_count, shared_max;
- struct fence *shared[];
+ struct fence __rcu *shared[];
};
struct reservation_object {
struct ww_mutex lock;
+ seqcount_t seq;
- struct fence *fence_excl;
- struct reservation_object_list *fence;
+ struct fence __rcu *fence_excl;
+ struct reservation_object_list __rcu *fence;
struct reservation_object_list *staged;
};
+#define reservation_object_held(obj) lockdep_is_held(&(obj)->lock.base)
#define reservation_object_assert_held(obj) \
lockdep_assert_held(&(obj)->lock.base)
@@ -66,8 +73,9 @@ reservation_object_init(struct reservation_object *obj)
{
ww_mutex_init(&obj->lock, &reservation_ww_class);
- obj->fence_excl = NULL;
- obj->fence = NULL;
+ __seqcount_init(&obj->seq, reservation_seqcount_string, &reservation_seqcount_class);
+ RCU_INIT_POINTER(obj->fence, NULL);
+ RCU_INIT_POINTER(obj->fence_excl, NULL);
obj->staged = NULL;
}
@@ -76,18 +84,20 @@ reservation_object_fini(struct reservation_object *obj)
{
int i;
struct reservation_object_list *fobj;
+ struct fence *excl;
/*
* This object should be dead and all references must have
- * been released to it.
+ * been released to it, so no need to be protected with rcu.
*/
- if (obj->fence_excl)
- fence_put(obj->fence_excl);
+ excl = rcu_dereference_protected(obj->fence_excl, 1);
+ if (excl)
+ fence_put(excl);
- fobj = obj->fence;
+ fobj = rcu_dereference_protected(obj->fence, 1);
if (fobj) {
for (i = 0; i < fobj->shared_count; ++i)
- fence_put(fobj->shared[i]);
+ fence_put(rcu_dereference_protected(fobj->shared[i], 1));
kfree(fobj);
}
@@ -99,17 +109,15 @@ reservation_object_fini(struct reservation_object *obj)
static inline struct reservation_object_list *
reservation_object_get_list(struct reservation_object *obj)
{
- reservation_object_assert_held(obj);
-
- return obj->fence;
+ return rcu_dereference_protected(obj->fence,
+ reservation_object_held(obj));
}
static inline struct fence *
reservation_object_get_excl(struct reservation_object *obj)
{
- reservation_object_assert_held(obj);
-
- return obj->fence_excl;
+ return rcu_dereference_protected(obj->fence_excl,
+ reservation_object_held(obj));
}
int reservation_object_reserve_shared(struct reservation_object *obj);
@@ -119,4 +127,16 @@ void reservation_object_add_shared_fence(struct reservation_object *obj,
void reservation_object_add_excl_fence(struct reservation_object *obj,
struct fence *fence);
+int reservation_object_get_fences_rcu(struct reservation_object *obj,
+ struct fence **pfence_excl,
+ unsigned *pshared_count,
+ struct fence ***pshared);
+
+long reservation_object_wait_timeout_rcu(struct reservation_object *obj,
+ bool wait_all, bool intr,
+ unsigned long timeout);
+
+bool reservation_object_test_signaled_rcu(struct reservation_object *obj,
+ bool test_all);
+
#endif /* _LINUX_RESERVATION_H */