| Message ID | 20200714212401.15825-3-chris@chris-wilson.co.uk (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v2,1/3] dma-buf/sw_sync: Avoid recursive lock during fence signal. | expand |
Still Reviewed-by: Bas Nieuwenhuizen <bas@basnieuwenhuizen.nl> On Tue, Jul 14, 2020 at 11:24 PM Chris Wilson <chris@chris-wilson.co.uk> wrote: > > Since we decouple the sync_pt from the timeline tree upon release, in > order to allow releasing the sync_pt from a signal callback we need to > separate the sync_pt signaling lock from the timeline tree lock. > > v2: Mark up the unlocked read of the current timeline value. > v3: Store a timeline pointer in the sync_pt as we cannot use the common > fence->lock trick to find our parent anymore. > > Suggested-by: Bas Nieuwenhuizen <bas@basnieuwenhuizen.nl> > Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> > Cc: Bas Nieuwenhuizen <bas@basnieuwenhuizen.nl> > --- > drivers/dma-buf/sw_sync.c | 40 +++++++++++++++++++++--------------- > drivers/dma-buf/sync_debug.c | 2 +- > drivers/dma-buf/sync_debug.h | 13 +++++++----- > 3 files changed, 32 insertions(+), 23 deletions(-) > > diff --git a/drivers/dma-buf/sw_sync.c b/drivers/dma-buf/sw_sync.c > index 807c82148062..17a5c1a3b7ce 100644 > --- a/drivers/dma-buf/sw_sync.c > +++ b/drivers/dma-buf/sw_sync.c > @@ -123,33 +123,39 @@ static const char *timeline_fence_get_driver_name(struct dma_fence *fence) > > static const char *timeline_fence_get_timeline_name(struct dma_fence *fence) > { > - struct sync_timeline *parent = dma_fence_parent(fence); > - > - return parent->name; > + return sync_timeline(fence)->name; > } > > static void timeline_fence_release(struct dma_fence *fence) > { > struct sync_pt *pt = dma_fence_to_sync_pt(fence); > - struct sync_timeline *parent = dma_fence_parent(fence); > - unsigned long flags; > + struct sync_timeline *parent = pt->timeline; > > - spin_lock_irqsave(fence->lock, flags); > if (!list_empty(&pt->link)) { > - list_del(&pt->link); > - rb_erase(&pt->node, &parent->pt_tree); > + unsigned long flags; > + > + spin_lock_irqsave(&parent->lock, flags); > + if (!list_empty(&pt->link)) { > + list_del(&pt->link); > + rb_erase(&pt->node, &parent->pt_tree); > + } > + spin_unlock_irqrestore(&parent->lock, flags); > } > - spin_unlock_irqrestore(fence->lock, flags); > > sync_timeline_put(parent); > dma_fence_free(fence); > } > > -static bool timeline_fence_signaled(struct dma_fence *fence) > +static int timeline_value(struct dma_fence *fence) > { > - struct sync_timeline *parent = dma_fence_parent(fence); > + return READ_ONCE(sync_timeline(fence)->value); > +} > > - return !__dma_fence_is_later(fence->seqno, parent->value, fence->ops); > +static bool timeline_fence_signaled(struct dma_fence *fence) > +{ > + return !__dma_fence_is_later(fence->seqno, > + timeline_value(fence), > + fence->ops); > } > > static bool timeline_fence_enable_signaling(struct dma_fence *fence) > @@ -166,9 +172,7 @@ static void timeline_fence_value_str(struct dma_fence *fence, > static void timeline_fence_timeline_value_str(struct dma_fence *fence, > char *str, int size) > { > - struct sync_timeline *parent = dma_fence_parent(fence); > - > - snprintf(str, size, "%d", parent->value); > + snprintf(str, size, "%d", timeline_value(fence)); > } > > static const struct dma_fence_ops timeline_fence_ops = { > @@ -252,12 +256,14 @@ static struct sync_pt *sync_pt_create(struct sync_timeline *obj, > return NULL; > > sync_timeline_get(obj); > - dma_fence_init(&pt->base, &timeline_fence_ops, &obj->lock, > + spin_lock_init(&pt->lock); > + dma_fence_init(&pt->base, &timeline_fence_ops, &pt->lock, > obj->context, value); > INIT_LIST_HEAD(&pt->link); > + pt->timeline = obj; > > spin_lock_irq(&obj->lock); > - if (!dma_fence_is_signaled_locked(&pt->base)) { > + if (!dma_fence_is_signaled(&pt->base)) { > struct rb_node **p = &obj->pt_tree.rb_node; > struct rb_node *parent = NULL; > > diff --git a/drivers/dma-buf/sync_debug.c b/drivers/dma-buf/sync_debug.c > index 101394f16930..2188ee17e889 100644 > --- a/drivers/dma-buf/sync_debug.c > +++ b/drivers/dma-buf/sync_debug.c > @@ -65,7 +65,7 @@ static const char *sync_status_str(int status) > static void sync_print_fence(struct seq_file *s, > struct dma_fence *fence, bool show) > { > - struct sync_timeline *parent = dma_fence_parent(fence); > + struct sync_timeline *parent = sync_timeline(fence); > int status; > > status = dma_fence_get_status_locked(fence); > diff --git a/drivers/dma-buf/sync_debug.h b/drivers/dma-buf/sync_debug.h > index 6176e52ba2d7..56589dae2159 100644 > --- a/drivers/dma-buf/sync_debug.h > +++ b/drivers/dma-buf/sync_debug.h > @@ -45,23 +45,26 @@ struct sync_timeline { > struct list_head sync_timeline_list; > }; > > -static inline struct sync_timeline *dma_fence_parent(struct dma_fence *fence) > -{ > - return container_of(fence->lock, struct sync_timeline, lock); > -} > - > /** > * struct sync_pt - sync_pt object > * @base: base fence object > * @link: link on the sync timeline's list > * @node: node in the sync timeline's tree > + * @lock: fence signaling lock > */ > struct sync_pt { > struct dma_fence base; > + struct sync_timeline *timeline; > struct list_head link; > struct rb_node node; > + spinlock_t lock; > }; > > +static inline struct sync_timeline *sync_timeline(struct dma_fence *fence) > +{ > + return container_of(fence, struct sync_pt, base)->timeline; > +} > + > extern const struct file_operations sw_sync_debugfs_fops; > > void sync_timeline_debug_add(struct sync_timeline *obj); > -- > 2.20.1 >
diff --git a/drivers/dma-buf/sw_sync.c b/drivers/dma-buf/sw_sync.c index 807c82148062..17a5c1a3b7ce 100644 --- a/drivers/dma-buf/sw_sync.c +++ b/drivers/dma-buf/sw_sync.c @@ -123,33 +123,39 @@ static const char *timeline_fence_get_driver_name(struct dma_fence *fence) static const char *timeline_fence_get_timeline_name(struct dma_fence *fence) { - struct sync_timeline *parent = dma_fence_parent(fence); - - return parent->name; + return sync_timeline(fence)->name; } static void timeline_fence_release(struct dma_fence *fence) { struct sync_pt *pt = dma_fence_to_sync_pt(fence); - struct sync_timeline *parent = dma_fence_parent(fence); - unsigned long flags; + struct sync_timeline *parent = pt->timeline; - spin_lock_irqsave(fence->lock, flags); if (!list_empty(&pt->link)) { - list_del(&pt->link); - rb_erase(&pt->node, &parent->pt_tree); + unsigned long flags; + + spin_lock_irqsave(&parent->lock, flags); + if (!list_empty(&pt->link)) { + list_del(&pt->link); + rb_erase(&pt->node, &parent->pt_tree); + } + spin_unlock_irqrestore(&parent->lock, flags); } - spin_unlock_irqrestore(fence->lock, flags); sync_timeline_put(parent); dma_fence_free(fence); } -static bool timeline_fence_signaled(struct dma_fence *fence) +static int timeline_value(struct dma_fence *fence) { - struct sync_timeline *parent = dma_fence_parent(fence); + return READ_ONCE(sync_timeline(fence)->value); +} - return !__dma_fence_is_later(fence->seqno, parent->value, fence->ops); +static bool timeline_fence_signaled(struct dma_fence *fence) +{ + return !__dma_fence_is_later(fence->seqno, + timeline_value(fence), + fence->ops); } static bool timeline_fence_enable_signaling(struct dma_fence *fence) @@ -166,9 +172,7 @@ static void timeline_fence_value_str(struct dma_fence *fence, static void timeline_fence_timeline_value_str(struct dma_fence *fence, char *str, int size) { - struct sync_timeline *parent = dma_fence_parent(fence); - - snprintf(str, size, "%d", parent->value); + snprintf(str, size, "%d", timeline_value(fence)); } static const struct dma_fence_ops timeline_fence_ops = { @@ -252,12 +256,14 @@ static struct sync_pt *sync_pt_create(struct sync_timeline *obj, return NULL; sync_timeline_get(obj); - dma_fence_init(&pt->base, &timeline_fence_ops, &obj->lock, + spin_lock_init(&pt->lock); + dma_fence_init(&pt->base, &timeline_fence_ops, &pt->lock, obj->context, value); INIT_LIST_HEAD(&pt->link); + pt->timeline = obj; spin_lock_irq(&obj->lock); - if (!dma_fence_is_signaled_locked(&pt->base)) { + if (!dma_fence_is_signaled(&pt->base)) { struct rb_node **p = &obj->pt_tree.rb_node; struct rb_node *parent = NULL; diff --git a/drivers/dma-buf/sync_debug.c b/drivers/dma-buf/sync_debug.c index 101394f16930..2188ee17e889 100644 --- a/drivers/dma-buf/sync_debug.c +++ b/drivers/dma-buf/sync_debug.c @@ -65,7 +65,7 @@ static const char *sync_status_str(int status) static void sync_print_fence(struct seq_file *s, struct dma_fence *fence, bool show) { - struct sync_timeline *parent = dma_fence_parent(fence); + struct sync_timeline *parent = sync_timeline(fence); int status; status = dma_fence_get_status_locked(fence); diff --git a/drivers/dma-buf/sync_debug.h b/drivers/dma-buf/sync_debug.h index 6176e52ba2d7..56589dae2159 100644 --- a/drivers/dma-buf/sync_debug.h +++ b/drivers/dma-buf/sync_debug.h @@ -45,23 +45,26 @@ struct sync_timeline { struct list_head sync_timeline_list; }; -static inline struct sync_timeline *dma_fence_parent(struct dma_fence *fence) -{ - return container_of(fence->lock, struct sync_timeline, lock); -} - /** * struct sync_pt - sync_pt object * @base: base fence object * @link: link on the sync timeline's list * @node: node in the sync timeline's tree + * @lock: fence signaling lock */ struct sync_pt { struct dma_fence base; + struct sync_timeline *timeline; struct list_head link; struct rb_node node; + spinlock_t lock; }; +static inline struct sync_timeline *sync_timeline(struct dma_fence *fence) +{ + return container_of(fence, struct sync_pt, base)->timeline; +} + extern const struct file_operations sw_sync_debugfs_fops; void sync_timeline_debug_add(struct sync_timeline *obj);
Since we decouple the sync_pt from the timeline tree upon release, in order to allow releasing the sync_pt from a signal callback we need to separate the sync_pt signaling lock from the timeline tree lock. v2: Mark up the unlocked read of the current timeline value. v3: Store a timeline pointer in the sync_pt as we cannot use the common fence->lock trick to find our parent anymore. Suggested-by: Bas Nieuwenhuizen <bas@basnieuwenhuizen.nl> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> Cc: Bas Nieuwenhuizen <bas@basnieuwenhuizen.nl> --- drivers/dma-buf/sw_sync.c | 40 +++++++++++++++++++++--------------- drivers/dma-buf/sync_debug.c | 2 +- drivers/dma-buf/sync_debug.h | 13 +++++++----- 3 files changed, 32 insertions(+), 23 deletions(-)