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reservation: add headerdoc comments

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Signed-off-by: Rob Clark <robdclark@gmail.com>
Signed-off-by: Sumit Semwal <sumit.semwal@linaro.org>
This commit is contained in:
Rob Clark 2016-03-31 16:26:51 -04:00 committed by Sumit Semwal
parent e2082e3ab8
commit dad6c3945f
2 changed files with 121 additions and 4 deletions
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72
drivers/dma-buf/reservation.c
View File

@ -35,6 +35,17 @@
#include <linux/reservation.h>
#include <linux/export.h>
/**
* DOC: Reservation Object Overview
*
* The reservation object provides a mechanism to manage shared and
* exclusive fences associated with a buffer. A reservation object
* can have attached one exclusive fence (normally associated with
* write operations) or N shared fences (read operations). The RCU
* mechanism is used to protect read access to fences from locked
* write-side updates.
*/
DEFINE_WW_CLASS(reservation_ww_class);
EXPORT_SYMBOL(reservation_ww_class);
@ -43,9 +54,17 @@ EXPORT_SYMBOL(reservation_seqcount_class);
const char reservation_seqcount_string[] = "reservation_seqcount";
EXPORT_SYMBOL(reservation_seqcount_string);
/*
* Reserve space to add a shared fence to a reservation_object,
* must be called with obj->lock held.
/**
* reservation_object_reserve_shared - Reserve space to add a shared
* fence to a reservation_object.
* @obj: reservation object
*
* Should be called before reservation_object_add_shared_fence(). Must
* be called with obj->lock held.
*
* RETURNS
* Zero for success, or -errno
*/
int reservation_object_reserve_shared(struct reservation_object *obj)
{
@ -180,7 +199,11 @@ reservation_object_add_shared_replace(struct reservation_object *obj,
fence_put(old_fence);
}
/*
/**
* reservation_object_add_shared_fence - Add a fence to a shared slot
* @obj: the reservation object
* @fence: the shared fence to add
*
* Add a fence to a shared slot, obj->lock must be held, and
* reservation_object_reserve_shared_fence has been called.
*/
@ -200,6 +223,13 @@ void reservation_object_add_shared_fence(struct reservation_object *obj,
}
EXPORT_SYMBOL(reservation_object_add_shared_fence);
/**
* reservation_object_add_excl_fence - Add an exclusive fence.
* @obj: the reservation object
* @fence: the shared fence to add
*
* Add a fence to the exclusive slot. The obj->lock must be held.
*/
void reservation_object_add_excl_fence(struct reservation_object *obj,
struct fence *fence)
{
@ -233,6 +263,18 @@ void reservation_object_add_excl_fence(struct reservation_object *obj,
}
EXPORT_SYMBOL(reservation_object_add_excl_fence);
/**
* reservation_object_get_fences_rcu - Get an object's shared and exclusive
* fences without update side lock held
* @obj: the reservation object
* @pfence_excl: the returned exclusive fence (or NULL)
* @pshared_count: the number of shared fences returned
* @pshared: the array of shared fence ptrs returned (array is krealloc'd to
* the required size, and must be freed by caller)
*
* RETURNS
* Zero or -errno
*/
int reservation_object_get_fences_rcu(struct reservation_object *obj,
struct fence **pfence_excl,
unsigned *pshared_count,
@ -319,6 +361,18 @@ int reservation_object_get_fences_rcu(struct reservation_object *obj,
}
EXPORT_SYMBOL_GPL(reservation_object_get_fences_rcu);
/**
* reservation_object_wait_timeout_rcu - Wait on reservation's objects
* shared and/or exclusive fences.
* @obj: the reservation object
* @wait_all: if true, wait on all fences, else wait on just exclusive fence
* @intr: if true, do interruptible wait
* @timeout: timeout value in jiffies or zero to return immediately
*
* RETURNS
* Returns -ERESTARTSYS if interrupted, 0 if the wait timed out, or
* greater than zer on success.
*/
long reservation_object_wait_timeout_rcu(struct reservation_object *obj,
bool wait_all, bool intr,
unsigned long timeout)
@ -416,6 +470,16 @@ reservation_object_test_signaled_single(struct fence *passed_fence)
return ret;
}
/**
* reservation_object_test_signaled_rcu - Test if a reservation object's
* fences have been signaled.
* @obj: the reservation object
* @test_all: if true, test all fences, otherwise only test the exclusive
* fence
*
* RETURNS
* true if all fences signaled, else false
*/
bool reservation_object_test_signaled_rcu(struct reservation_object *obj,
bool test_all)
{

53
include/linux/reservation.h
View File

@ -49,12 +49,27 @@ 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 - a list of shared fences
* @rcu: for internal use
* @shared_count: table of shared fences
* @shared_max: for growing shared fence table
* @shared: shared fence table
*/
struct reservation_object_list {
struct rcu_head rcu;
u32 shared_count, shared_max;
struct fence __rcu *shared[];
};
/**
* struct reservation_object - a reservation object manages fences for a buffer
* @lock: update side lock
* @seq: sequence count for managing RCU read-side synchronization
* @fence_excl: the exclusive fence, if there is one currently
* @fence: list of current shared fences
* @staged: staged copy of shared fences for RCU updates
*/
struct reservation_object {
struct ww_mutex lock;
seqcount_t seq;
@ -68,6 +83,10 @@ struct reservation_object {
#define reservation_object_assert_held(obj) \
lockdep_assert_held(&(obj)->lock.base)
/**
* reservation_object_init - initialize a reservation object
* @obj: the reservation object
*/
static inline void
reservation_object_init(struct reservation_object *obj)
{
@ -79,6 +98,10 @@ reservation_object_init(struct reservation_object *obj)
obj->staged = NULL;
}
/**
* reservation_object_fini - destroys a reservation object
* @obj: the reservation object
*/
static inline void
reservation_object_fini(struct reservation_object *obj)
{
@ -106,6 +129,14 @@ reservation_object_fini(struct reservation_object *obj)
ww_mutex_destroy(&obj->lock);
}
/**
* reservation_object_get_list - get the reservation object's
* shared fence list, with update-side lock held
* @obj: the reservation object
*
* Returns the shared fence list. Does NOT take references to
* the fence. The obj->lock must be held.
*/
static inline struct reservation_object_list *
reservation_object_get_list(struct reservation_object *obj)
{
@ -113,6 +144,17 @@ reservation_object_get_list(struct reservation_object *obj)
reservation_object_held(obj));
}
/**
* reservation_object_get_excl - get the reservation object's
* exclusive fence, with update-side lock held
* @obj: the reservation object
*
* Returns the exclusive fence (if any). Does NOT take a
* reference. The obj->lock must be held.
*
* RETURNS
* The exclusive fence or NULL
*/
static inline struct fence *
reservation_object_get_excl(struct reservation_object *obj)
{
@ -120,6 +162,17 @@ reservation_object_get_excl(struct reservation_object *obj)
reservation_object_held(obj));
}
/**
* reservation_object_get_excl_rcu - get the reservation object's
* exclusive fence, without lock held.
* @obj: the reservation object
*
* If there is an exclusive fence, this atomically increments it's
* reference count and returns it.
*
* RETURNS
* The exclusive fence or NULL if none
*/
static inline struct fence *
reservation_object_get_excl_rcu(struct reservation_object *obj)
{