Ping once more! Adding a few more AMD people.

Any comments on this?

Thanks, Christian.

Am 12.10.18 um 10:22 schrieb Christian König:

Ping! Adding a few people directly and more mailing lists.

Can I get an acked-by/rb for this? It's only a cleanup and not much functional change.

Regards, Christian.

Am 04.10.2018 um 15:12 schrieb Christian König:

...

No need for that any more. Just replace the list when there isn't enough room any more for the additional fence.

Signed-off-by: Christian König christian.koenig@amd.com

drivers/dma-buf/reservation.c | 178 ++++++++++++++----------------------------   include/linux/reservation.h   |   4 -   2 files changed, 58 insertions(+), 124 deletions(-)

diff --git a/drivers/dma-buf/reservation.c b/drivers/dma-buf/reservation.c index 6c95f61a32e7..5825fc336a13 100644 --- a/drivers/dma-buf/reservation.c +++ b/drivers/dma-buf/reservation.c @@ -68,105 +68,23 @@ EXPORT_SYMBOL(reservation_seqcount_string);    */   int reservation_object_reserve_shared(struct reservation_object *obj)   { -    struct reservation_object_list *fobj, *old; -    u32 max; +    struct reservation_object_list *old, *new; +    unsigned int i, j, k, max;         old = reservation_object_get_list(obj);         if (old && old->shared_max) { -        if (old->shared_count < old->shared_max) { -            /* perform an in-place update */ -            kfree(obj->staged); -            obj->staged = NULL; +        if (old->shared_count < old->shared_max)               return 0; -        } else +        else               max = old->shared_max * 2; -    } else -        max = 4;

-    /* -     * resize obj->staged or allocate if it doesn't exist, -     * noop if already correct size -     */ -    fobj = krealloc(obj->staged, offsetof(typeof(*fobj), shared[max]), -            GFP_KERNEL); -    if (!fobj) -        return -ENOMEM;

-    obj->staged = fobj; -    fobj->shared_max = max; -    return 0; -} -EXPORT_SYMBOL(reservation_object_reserve_shared);

-static void -reservation_object_add_shared_inplace(struct reservation_object *obj, -                      struct reservation_object_list *fobj, -                      struct dma_fence *fence) -{ -    struct dma_fence *signaled = NULL; -    u32 i, signaled_idx;

-    dma_fence_get(fence);

-    preempt_disable(); -    write_seqcount_begin(&obj->seq);

-    for (i = 0; i < fobj->shared_count; ++i) { -        struct dma_fence *old_fence;

-        old_fence = rcu_dereference_protected(fobj->shared[i], -                        reservation_object_held(obj));

-        if (old_fence->context == fence->context) { -            /* memory barrier is added by write_seqcount_begin */ -            RCU_INIT_POINTER(fobj->shared[i], fence); -            write_seqcount_end(&obj->seq); -            preempt_enable();

-            dma_fence_put(old_fence); -            return; -        }

-        if (!signaled && dma_fence_is_signaled(old_fence)) { -            signaled = old_fence; -            signaled_idx = i; -        } -    }

-    /* -     * memory barrier is added by write_seqcount_begin, -     * fobj->shared_count is protected by this lock too -     */ -    if (signaled) { -        RCU_INIT_POINTER(fobj->shared[signaled_idx], fence);       } else { -        BUG_ON(fobj->shared_count >= fobj->shared_max);

• RCU_INIT_POINTER(fobj->shared[fobj->shared_count], fence);

-        fobj->shared_count++; +        max = 4;       }   -    write_seqcount_end(&obj->seq); -    preempt_enable();

-    dma_fence_put(signaled); -}

-static void -reservation_object_add_shared_replace(struct reservation_object *obj, -                      struct reservation_object_list *old, -                      struct reservation_object_list *fobj, -                      struct dma_fence *fence) -{ -    unsigned i, j, k;

-    dma_fence_get(fence);

-    if (!old) { -        RCU_INIT_POINTER(fobj->shared[0], fence); -        fobj->shared_count = 1; -        goto done; -    } +    new = kmalloc(offsetof(typeof(*new), shared[max]), GFP_KERNEL); +    if (!new) +        return -ENOMEM;         /*        * no need to bump fence refcounts, rcu_read access @@ -174,46 +92,45 @@ reservation_object_add_shared_replace(struct reservation_object *obj,        * references from the old struct are carried over to        * the new.        */ -    for (i = 0, j = 0, k = fobj->shared_max; i < old->shared_count; ++i) { -        struct dma_fence *check; +    for (i = 0, j = 0, k = max; i < (old ? old->shared_count : 0); ++i) { +        struct dma_fence *fence;   -        check = rcu_dereference_protected(old->shared[i], -                        reservation_object_held(obj));

-        if (check->context == fence->context || -            dma_fence_is_signaled(check)) -            RCU_INIT_POINTER(fobj->shared[--k], check); +        fence = rcu_dereference_protected(old->shared[i], +                          reservation_object_held(obj)); +        if (dma_fence_is_signaled(fence)) +            RCU_INIT_POINTER(new->shared[--k], fence);           else -            RCU_INIT_POINTER(fobj->shared[j++], check); +            RCU_INIT_POINTER(new->shared[j++], fence);       } -    fobj->shared_count = j; -    RCU_INIT_POINTER(fobj->shared[fobj->shared_count], fence); -    fobj->shared_count++; +    new->shared_count = j; +    new->shared_max = max;   -done:       preempt_disable();       write_seqcount_begin(&obj->seq);       /*        * RCU_INIT_POINTER can be used here,        * seqcount provides the necessary barriers        */ -    RCU_INIT_POINTER(obj->fence, fobj); +    RCU_INIT_POINTER(obj->fence, new);       write_seqcount_end(&obj->seq);       preempt_enable();         if (!old) -        return; +        return 0;         /* Drop the references to the signaled fences */ -    for (i = k; i < fobj->shared_max; ++i) { -        struct dma_fence *f; +    for (i = k; i < new->shared_max; ++i) { +        struct dma_fence *fence;   -        f = rcu_dereference_protected(fobj->shared[i], -                          reservation_object_held(obj)); -        dma_fence_put(f); +        fence = rcu_dereference_protected(new->shared[i], +                          reservation_object_held(obj)); +        dma_fence_put(fence);       }       kfree_rcu(old, rcu);

+    return 0;   } +EXPORT_SYMBOL(reservation_object_reserve_shared);     /**    * reservation_object_add_shared_fence - Add a fence to a shared slot @@ -226,15 +143,39 @@ reservation_object_add_shared_replace(struct reservation_object *obj,   void reservation_object_add_shared_fence(struct reservation_object *obj,                        struct dma_fence *fence)   { -    struct reservation_object_list *old, *fobj = obj->staged; +    struct reservation_object_list *fobj; +    unsigned int i;   -    old = reservation_object_get_list(obj); -    obj->staged = NULL; +    dma_fence_get(fence);

+    fobj = reservation_object_get_list(obj);   -    if (!fobj) -        reservation_object_add_shared_inplace(obj, old, fence); -    else -        reservation_object_add_shared_replace(obj, old, fobj, fence); +    preempt_disable(); +    write_seqcount_begin(&obj->seq);

+    for (i = 0; i < fobj->shared_count; ++i) { +        struct dma_fence *old_fence;

+        old_fence = rcu_dereference_protected(fobj->shared[i], +                              reservation_object_held(obj)); +        if (old_fence->context == fence->context || +            dma_fence_is_signaled(old_fence)) { +            dma_fence_put(old_fence); +            goto replace; +        } +    }

+    BUG_ON(fobj->shared_count >= fobj->shared_max); +    fobj->shared_count++;

+replace: +    /* +     * memory barrier is added by write_seqcount_begin, +     * fobj->shared_count is protected by this lock too +     */ +    RCU_INIT_POINTER(fobj->shared[i], fence); +    write_seqcount_end(&obj->seq); +    preempt_enable();   }   EXPORT_SYMBOL(reservation_object_add_shared_fence);   @@ -343,9 +284,6 @@ int reservation_object_copy_fences(struct reservation_object *dst,       new = dma_fence_get_rcu_safe(&src->fence_excl);       rcu_read_unlock();   -    kfree(dst->staged); -    dst->staged = NULL;

src_list = reservation_object_get_list(dst);       old = reservation_object_get_excl(dst);   diff --git a/include/linux/reservation.h b/include/linux/reservation.h index 02166e815afb..54cf6773a14c 100644 --- a/include/linux/reservation.h +++ b/include/linux/reservation.h @@ -68,7 +68,6 @@ struct reservation_object_list {    * @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; @@ -76,7 +75,6 @@ struct reservation_object {         struct dma_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) @@ -95,7 +93,6 @@ reservation_object_init(struct reservation_object *obj)       __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;   }     /** @@ -124,7 +121,6 @@ reservation_object_fini(struct reservation_object *obj)             kfree(fobj);       } -    kfree(obj->staged);         ww_mutex_destroy(&obj->lock);   }