diff options
| author | Maarten Lankhorst <maarten.lankhorst@canonical.com> | 2014-07-01 12:58:00 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2014-07-08 13:41:08 -0700 |
| commit | 3c3b177a9369b26890ced004867fb32708e8ef5b (patch) | |
| tree | d7f1840cd62b8c0d427ea56b203485c2e27bb29e /include/linux/fence.h | |
| parent | 04a5faa8cbe5a8eaf152cb88959ba6360c26e702 (diff) | |
| download | lwn-3c3b177a9369b26890ced004867fb32708e8ef5b.tar.gz lwn-3c3b177a9369b26890ced004867fb32708e8ef5b.zip | |
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/fence.h')
| -rw-r--r-- | include/linux/fence.h | 17 |
1 files changed, 17 insertions, 0 deletions
diff --git a/include/linux/fence.h b/include/linux/fence.h index b935cc650123..d174585b874b 100644 --- a/include/linux/fence.h +++ b/include/linux/fence.h @@ -28,6 +28,7 @@ #include <linux/kref.h> #include <linux/sched.h> #include <linux/printk.h> +#include <linux/rcupdate.h> struct fence; struct fence_ops; @@ -37,6 +38,7 @@ struct fence_cb; * struct fence - software synchronization primitive * @refcount: refcount for this fence * @ops: fence_ops associated with this fence + * @rcu: used for releasing fence with kfree_rcu * @cb_list: list of all callbacks to call * @lock: spin_lock_irqsave used for locking * @context: execution context this fence belongs to, returned by @@ -70,6 +72,7 @@ struct fence_cb; struct fence { struct kref refcount; const struct fence_ops *ops; + struct rcu_head rcu; struct list_head cb_list; spinlock_t *lock; unsigned context, seqno; @@ -192,6 +195,20 @@ static inline struct fence *fence_get(struct fence *fence) } /** + * fence_get_rcu - get a fence from a reservation_object_list with rcu read lock + * @fence: [in] fence to increase refcount of + * + * Function returns NULL if no refcount could be obtained, or the fence. + */ +static inline struct fence *fence_get_rcu(struct fence *fence) +{ + if (kref_get_unless_zero(&fence->refcount)) + return fence; + else + return NULL; +} + +/** * fence_put - decreases refcount of the fence * @fence: [in] fence to reduce refcount of */ |