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drm/ttm: convert to the reservation api

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Now that the code is compatible in semantics, flip the switch.
Use ww_mutex instead of the homegrown implementation.

ww_mutex uses -EDEADLK to signal that the caller has to back off,
and -EALREADY to indicate this buffer is already held by the caller.

ttm used -EAGAIN and -EDEADLK for those, respectively. So some changes
were needed to handle this correctly.

Signed-off-by: Maarten Lankhorst <maarten.lankhorst@canonical.com>
Reviewed-by: Jerome Glisse <jglisse@redhat.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
This commit is contained in:
Maarten Lankhorst 2013-06-27 13:48:19 +02:00 committed by Dave Airlie
parent b580c9e2b7
commit 5e33840511
7 changed files with 80 additions and 194 deletions
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2
drivers/gpu/drm/nouveau/nouveau_gem.c
View File

@ -368,7 +368,7 @@ retry:
ret = ttm_bo_reserve(&nvbo->bo, true, false, true, &op->ticket);
if (ret) {
validate_fini_no_ticket(op, NULL);
if (unlikely(ret == -EAGAIN)) {
if (unlikely(ret == -EDEADLK)) {
ret = ttm_bo_reserve_slowpath(&nvbo->bo, true,
&op->ticket);
if (!ret)

5
drivers/gpu/drm/qxl/qxl_object.h
View File

@ -57,11 +57,6 @@ static inline unsigned long qxl_bo_size(struct qxl_bo *bo)
return bo->tbo.num_pages << PAGE_SHIFT;
}
static inline bool qxl_bo_is_reserved(struct qxl_bo *bo)
{
return !!atomic_read(&bo->tbo.reserved);
}
static inline u64 qxl_bo_mmap_offset(struct qxl_bo *bo)
{
return bo->tbo.addr_space_offset;

190
drivers/gpu/drm/ttm/ttm_bo.c
View File

@ -150,6 +150,9 @@ static void ttm_bo_release_list(struct kref *list_kref)
if (bo->ttm)
ttm_tt_destroy(bo->ttm);
atomic_dec(&bo->glob->bo_count);
if (bo->resv == &bo->ttm_resv)
reservation_object_fini(&bo->ttm_resv);
if (bo->destroy)
bo->destroy(bo);
else {
@ -158,18 +161,6 @@ static void ttm_bo_release_list(struct kref *list_kref)
ttm_mem_global_free(bdev->glob->mem_glob, acc_size);
}
static int ttm_bo_wait_unreserved(struct ttm_buffer_object *bo,
bool interruptible)
{
if (interruptible) {
return wait_event_interruptible(bo->event_queue,
!ttm_bo_is_reserved(bo));
} else {
wait_event(bo->event_queue, !ttm_bo_is_reserved(bo));
return 0;
}
}
void ttm_bo_add_to_lru(struct ttm_buffer_object *bo)
{
struct ttm_bo_device *bdev = bo->bdev;
@ -218,65 +209,27 @@ int ttm_bo_reserve_nolru(struct ttm_buffer_object *bo,
bool no_wait, bool use_ticket,
struct ww_acquire_ctx *ticket)
{
int ret;
int ret = 0;
while (unlikely(atomic_xchg(&bo->reserved, 1) != 0)) {
/**
* Deadlock avoidance for multi-bo reserving.
*/
if (use_ticket && bo->seq_valid) {
/**
* We've already reserved this one.
*/
if (unlikely(ticket->stamp == bo->val_seq))
return -EDEADLK;
/**
* Already reserved by a thread that will not back
* off for us. We need to back off.
*/
if (unlikely(ticket->stamp - bo->val_seq <= LONG_MAX))
return -EAGAIN;
}
if (no_wait) {
bool success;
if (no_wait)
/* not valid any more, fix your locking! */
if (WARN_ON(ticket))
return -EBUSY;
ret = ttm_bo_wait_unreserved(bo, interruptible);
if (unlikely(ret))
return ret;
success = ww_mutex_trylock(&bo->resv->lock);
return success ? 0 : -EBUSY;
}
if (use_ticket) {
bool wake_up = false;
/**
* Wake up waiters that may need to recheck for deadlock,
* if we decreased the sequence number.
*/
if (unlikely((bo->val_seq - ticket->stamp <= LONG_MAX)
|| !bo->seq_valid))
wake_up = true;
/*
* In the worst case with memory ordering these values can be
* seen in the wrong order. However since we call wake_up_all
* in that case, this will hopefully not pose a problem,
* and the worst case would only cause someone to accidentally
* hit -EAGAIN in ttm_bo_reserve when they see old value of
* val_seq. However this would only happen if seq_valid was
* written before val_seq was, and just means some slightly
* increased cpu usage
*/
bo->val_seq = ticket->stamp;
bo->seq_valid = true;
if (wake_up)
wake_up_all(&bo->event_queue);
} else {
bo->seq_valid = false;
}
return 0;
if (interruptible)
ret = ww_mutex_lock_interruptible(&bo->resv->lock,
ticket);
else
ret = ww_mutex_lock(&bo->resv->lock, ticket);
if (ret == -EINTR)
return -ERESTARTSYS;
return ret;
}
EXPORT_SYMBOL(ttm_bo_reserve);
@ -313,50 +266,27 @@ int ttm_bo_reserve(struct ttm_buffer_object *bo,
return ret;
}
int ttm_bo_reserve_slowpath_nolru(struct ttm_buffer_object *bo,
bool interruptible,
struct ww_acquire_ctx *ticket)
{
bool wake_up = false;
int ret;
while (unlikely(atomic_xchg(&bo->reserved, 1) != 0)) {
WARN_ON(bo->seq_valid && ticket->stamp == bo->val_seq);
ret = ttm_bo_wait_unreserved(bo, interruptible);
if (unlikely(ret))
return ret;
}
if (bo->val_seq - ticket->stamp < LONG_MAX || !bo->seq_valid)
wake_up = true;
/**
* Wake up waiters that may need to recheck for deadlock,
* if we decreased the sequence number.
*/
bo->val_seq = ticket->stamp;
bo->seq_valid = true;
if (wake_up)
wake_up_all(&bo->event_queue);
return 0;
}
int ttm_bo_reserve_slowpath(struct ttm_buffer_object *bo,
bool interruptible, struct ww_acquire_ctx *ticket)
{
struct ttm_bo_global *glob = bo->glob;
int put_count, ret;
int put_count = 0;
int ret = 0;
ret = ttm_bo_reserve_slowpath_nolru(bo, interruptible, ticket);
if (likely(!ret)) {
if (interruptible)
ret = ww_mutex_lock_slow_interruptible(&bo->resv->lock,
ticket);
else
ww_mutex_lock_slow(&bo->resv->lock, ticket);
if (likely(ret == 0)) {
spin_lock(&glob->lru_lock);
put_count = ttm_bo_del_from_lru(bo);
spin_unlock(&glob->lru_lock);
ttm_bo_list_ref_sub(bo, put_count, true);
}
} else if (ret == -EINTR)
ret = -ERESTARTSYS;
return ret;
}
EXPORT_SYMBOL(ttm_bo_reserve_slowpath);
@ -364,8 +294,7 @@ EXPORT_SYMBOL(ttm_bo_reserve_slowpath);
void ttm_bo_unreserve_ticket_locked(struct ttm_buffer_object *bo, struct ww_acquire_ctx *ticket)
{
ttm_bo_add_to_lru(bo);
atomic_set(&bo->reserved, 0);
wake_up_all(&bo->event_queue);
ww_mutex_unlock(&bo->resv->lock);
}
void ttm_bo_unreserve(struct ttm_buffer_object *bo)
@ -558,17 +487,7 @@ static void ttm_bo_cleanup_memtype_use(struct ttm_buffer_object *bo)
}
ttm_bo_mem_put(bo, &bo->mem);
atomic_set(&bo->reserved, 0);
wake_up_all(&bo->event_queue);
/*
* Since the final reference to this bo may not be dropped by
* the current task we have to put a memory barrier here to make
* sure the changes done in this function are always visible.
*
* This function only needs protection against the final kref_put.
*/
smp_mb__before_atomic_dec();
ww_mutex_unlock (&bo->resv->lock);
}
static void ttm_bo_cleanup_refs_or_queue(struct ttm_buffer_object *bo)
@ -600,10 +519,8 @@ static void ttm_bo_cleanup_refs_or_queue(struct ttm_buffer_object *bo)
sync_obj = driver->sync_obj_ref(bo->sync_obj);
spin_unlock(&bdev->fence_lock);
if (!ret) {
atomic_set(&bo->reserved, 0);
wake_up_all(&bo->event_queue);
}
if (!ret)
ww_mutex_unlock(&bo->resv->lock);
kref_get(&bo->list_kref);
list_add_tail(&bo->ddestroy, &bdev->ddestroy);
@ -653,8 +570,7 @@ static int ttm_bo_cleanup_refs_and_unlock(struct ttm_buffer_object *bo,
sync_obj = driver->sync_obj_ref(bo->sync_obj);
spin_unlock(&bdev->fence_lock);
atomic_set(&bo->reserved, 0);
wake_up_all(&bo->event_queue);
ww_mutex_unlock(&bo->resv->lock);
spin_unlock(&glob->lru_lock);
ret = driver->sync_obj_wait(sync_obj, false, interruptible);
@ -692,8 +608,7 @@ static int ttm_bo_cleanup_refs_and_unlock(struct ttm_buffer_object *bo,
spin_unlock(&bdev->fence_lock);
if (ret || unlikely(list_empty(&bo->ddestroy))) {
atomic_set(&bo->reserved, 0);
wake_up_all(&bo->event_queue);
ww_mutex_unlock(&bo->resv->lock);
spin_unlock(&glob->lru_lock);
return ret;
}
@ -1253,6 +1168,7 @@ int ttm_bo_init(struct ttm_bo_device *bdev,
int ret = 0;
unsigned long num_pages;
struct ttm_mem_global *mem_glob = bdev->glob->mem_glob;
bool locked;
ret = ttm_mem_global_alloc(mem_glob, acc_size, false, false);
if (ret) {
@ -1279,8 +1195,6 @@ int ttm_bo_init(struct ttm_bo_device *bdev,
kref_init(&bo->kref);
kref_init(&bo->list_kref);
atomic_set(&bo->cpu_writers, 0);
atomic_set(&bo->reserved, 1);
init_waitqueue_head(&bo->event_queue);
INIT_LIST_HEAD(&bo->lru);
INIT_LIST_HEAD(&bo->ddestroy);
INIT_LIST_HEAD(&bo->swap);
@ -1298,37 +1212,34 @@ int ttm_bo_init(struct ttm_bo_device *bdev,
bo->mem.bus.io_reserved_count = 0;
bo->priv_flags = 0;
bo->mem.placement = (TTM_PL_FLAG_SYSTEM | TTM_PL_FLAG_CACHED);
bo->seq_valid = false;
bo->persistent_swap_storage = persistent_swap_storage;
bo->acc_size = acc_size;
bo->sg = sg;
bo->resv = &bo->ttm_resv;
reservation_object_init(bo->resv);
atomic_inc(&bo->glob->bo_count);
ret = ttm_bo_check_placement(bo, placement);
if (unlikely(ret != 0))
goto out_err;
/*
* For ttm_bo_type_device buffers, allocate
* address space from the device.
*/
if (bo->type == ttm_bo_type_device ||
bo->type == ttm_bo_type_sg) {
if (likely(!ret) &&
(bo->type == ttm_bo_type_device ||
bo->type == ttm_bo_type_sg))
ret = ttm_bo_setup_vm(bo);
if (ret)
goto out_err;
}
ret = ttm_bo_validate(bo, placement, interruptible, false);
if (ret)
goto out_err;
locked = ww_mutex_trylock(&bo->resv->lock);
WARN_ON(!locked);
if (likely(!ret))
ret = ttm_bo_validate(bo, placement, interruptible, false);
ttm_bo_unreserve(bo);
return 0;
out_err:
ttm_bo_unreserve(bo);
ttm_bo_unref(&bo);
if (unlikely(ret))
ttm_bo_unref(&bo);
return ret;
}
@ -1941,8 +1852,7 @@ out:
* already swapped buffer.
*/
atomic_set(&bo->reserved, 0);
wake_up_all(&bo->event_queue);
ww_mutex_unlock(&bo->resv->lock);
kref_put(&bo->list_kref, ttm_bo_release_list);
return ret;
}

6
drivers/gpu/drm/ttm/ttm_bo_util.c
View File

@ -433,6 +433,7 @@ static int ttm_buffer_object_transfer(struct ttm_buffer_object *bo,
struct ttm_buffer_object *fbo;
struct ttm_bo_device *bdev = bo->bdev;
struct ttm_bo_driver *driver = bdev->driver;
int ret;
fbo = kmalloc(sizeof(*fbo), GFP_KERNEL);
if (!fbo)
@ -445,7 +446,6 @@ static int ttm_buffer_object_transfer(struct ttm_buffer_object *bo,
* TODO: Explicit member copy would probably be better here.
*/
init_waitqueue_head(&fbo->event_queue);
INIT_LIST_HEAD(&fbo->ddestroy);
INIT_LIST_HEAD(&fbo->lru);
INIT_LIST_HEAD(&fbo->swap);
@ -463,6 +463,10 @@ static int ttm_buffer_object_transfer(struct ttm_buffer_object *bo,
kref_init(&fbo->kref);
fbo->destroy = &ttm_transfered_destroy;
fbo->acc_size = 0;
fbo->resv = &fbo->ttm_resv;
reservation_object_init(fbo->resv);
ret = ww_mutex_trylock(&fbo->resv->lock);
WARN_ON(!ret);
*new_obj = fbo;
return 0;

45
drivers/gpu/drm/ttm/ttm_execbuf_util.c
View File

@ -48,8 +48,7 @@ static void ttm_eu_backoff_reservation_locked(struct list_head *list,
entry->removed = false;
} else {
atomic_set(&bo->reserved, 0);
wake_up_all(&bo->event_queue);
ww_mutex_unlock(&bo->resv->lock);
}
}
}
@ -134,8 +133,6 @@ int ttm_eu_reserve_buffers(struct ww_acquire_ctx *ticket,
glob = entry->bo->glob;
ww_acquire_init(ticket, &reservation_ww_class);
spin_lock(&glob->lru_lock);
retry:
list_for_each_entry(entry, list, head) {
struct ttm_buffer_object *bo = entry->bo;
@ -144,42 +141,34 @@ retry:
if (entry->reserved)
continue;
ret = ttm_bo_reserve_nolru(bo, true, true, true, ticket);
switch (ret) {
case 0:
break;
case -EBUSY:
ttm_eu_del_from_lru_locked(list);
spin_unlock(&glob->lru_lock);
ret = ttm_bo_reserve_nolru(bo, true, false,
true, ticket);
ret = ttm_bo_reserve_nolru(bo, true, false, true, ticket);
if (ret == -EDEADLK) {
/* uh oh, we lost out, drop every reservation and try
* to only reserve this buffer, then start over if
* this succeeds.
*/
spin_lock(&glob->lru_lock);
if (!ret)
break;
if (unlikely(ret != -EAGAIN))
goto err;
/* fallthrough */
case -EAGAIN:
ttm_eu_backoff_reservation_locked(list, ticket);
spin_unlock(&glob->lru_lock);
ttm_eu_list_ref_sub(list);
ret = ttm_bo_reserve_slowpath_nolru(bo, true, ticket);
if (unlikely(ret != 0))
ret = ww_mutex_lock_slow_interruptible(&bo->resv->lock,
ticket);
if (unlikely(ret != 0)) {
if (ret == -EINTR)
ret = -ERESTARTSYS;
goto err_fini;
}
spin_lock(&glob->lru_lock);
entry->reserved = true;
if (unlikely(atomic_read(&bo->cpu_writers) > 0)) {
ret = -EBUSY;
goto err;
}
goto retry;
default:
} else if (ret)
goto err;
}
entry->reserved = true;
if (unlikely(atomic_read(&bo->cpu_writers) > 0)) {
@ -189,12 +178,14 @@ retry:
}
ww_acquire_done(ticket);
spin_lock(&glob->lru_lock);
ttm_eu_del_from_lru_locked(list);
spin_unlock(&glob->lru_lock);
ttm_eu_list_ref_sub(list);
return 0;
err:
spin_lock(&glob->lru_lock);
ttm_eu_backoff_reservation_locked(list, ticket);
spin_unlock(&glob->lru_lock);
ttm_eu_list_ref_sub(list);

25
include/drm/ttm/ttm_bo_api.h
View File

@ -39,6 +39,7 @@
#include <linux/mm.h>
#include <linux/rbtree.h>
#include <linux/bitmap.h>
#include <linux/reservation.h>
struct ttm_bo_device;
@ -153,7 +154,6 @@ struct ttm_tt;
* Lru lists may keep one refcount, the delayed delete list, and kref != 0
* keeps one refcount. When this refcount reaches zero,
* the object is destroyed.
* @event_queue: Queue for processes waiting on buffer object status change.
* @mem: structure describing current placement.
* @persistent_swap_storage: Usually the swap storage is deleted for buffers
* pinned in physical memory. If this behaviour is not desired, this member
@ -164,12 +164,6 @@ struct ttm_tt;
* @lru: List head for the lru list.
* @ddestroy: List head for the delayed destroy list.
* @swap: List head for swap LRU list.
* @val_seq: Sequence of the validation holding the @reserved lock.
* Used to avoid starvation when many processes compete to validate the
* buffer. This member is protected by the bo_device::lru_lock.
* @seq_valid: The value of @val_seq is valid. This value is protected by
* the bo_device::lru_lock.
* @reserved: Deadlock-free lock used for synchronization state transitions.
* @sync_obj: Pointer to a synchronization object.
* @priv_flags: Flags describing buffer object internal state.
* @vm_rb: Rb node for the vm rb tree.
@ -209,10 +203,9 @@ struct ttm_buffer_object {
struct kref kref;
struct kref list_kref;
wait_queue_head_t event_queue;
/**
* Members protected by the bo::reserved lock.
* Members protected by the bo::resv::reserved lock.
*/
struct ttm_mem_reg mem;
@ -234,15 +227,6 @@ struct ttm_buffer_object {
struct list_head ddestroy;
struct list_head swap;
struct list_head io_reserve_lru;
unsigned long val_seq;
bool seq_valid;
/**
* Members protected by the bdev::lru_lock
* only when written to.
*/
atomic_t reserved;
/**
* Members protected by struct buffer_object_device::fence_lock
@ -272,6 +256,9 @@ struct ttm_buffer_object {
uint32_t cur_placement;
struct sg_table *sg;
struct reservation_object *resv;
struct reservation_object ttm_resv;
};
/**
@ -736,7 +723,7 @@ extern void ttm_bo_swapout_all(struct ttm_bo_device *bdev);
*/
static inline bool ttm_bo_is_reserved(struct ttm_buffer_object *bo)
{
return atomic_read(&bo->reserved);
return ww_mutex_is_locked(&bo->resv->lock);
}
#endif

1
include/drm/ttm/ttm_execbuf_util.h
View File

@ -33,7 +33,6 @@
#include <ttm/ttm_bo_api.h>
#include <linux/list.h>
#include <linux/reservation.h>
/**
* struct ttm_validate_buffer