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authorMaarten Lankhorst <maarten.lankhorst@canonical.com>2014-12-01 19:11:06 +1000
committerBen Skeggs <bskeggs@redhat.com>2014-12-02 15:33:22 +1000
commit0ec5f02f0e2c6fe88ba5817790e11fe33ee298a7 (patch)
treea5490f5e7bfd3c723db4de9aa83bb0cb0d335d3d
parent19a10828814aa3ba483301b416b27f94330e0c80 (diff)
downloadkernel-0ec5f02f0e2c6fe88ba5817790e11fe33ee298a7.tar.gz
drm/nouveau: prevent stale fence->channel pointers, and protect with rcu
Tested-by: Alexandre Courbot <acourbot@nvidia.com> Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
-rw-r--r--drivers/gpu/drm/nouveau/nouveau_fence.c92
-rw-r--r--drivers/gpu/drm/nouveau/nouveau_fence.h4
2 files changed, 67 insertions, 29 deletions
diff --git a/drivers/gpu/drm/nouveau/nouveau_fence.c b/drivers/gpu/drm/nouveau/nouveau_fence.c
index 515cd9aebb99..f32a434724e3 100644
--- a/drivers/gpu/drm/nouveau/nouveau_fence.c
+++ b/drivers/gpu/drm/nouveau/nouveau_fence.c
@@ -52,20 +52,24 @@ nouveau_fctx(struct nouveau_fence *fence)
return container_of(fence->base.lock, struct nouveau_fence_chan, lock);
}
-static void
+static int
nouveau_fence_signal(struct nouveau_fence *fence)
{
+ int drop = 0;
+
fence_signal_locked(&fence->base);
list_del(&fence->head);
+ rcu_assign_pointer(fence->channel, NULL);
if (test_bit(FENCE_FLAG_USER_BITS, &fence->base.flags)) {
struct nouveau_fence_chan *fctx = nouveau_fctx(fence);
if (!--fctx->notify_ref)
- nvif_notify_put(&fctx->notify);
+ drop = 1;
}
fence_put(&fence->base);
+ return drop;
}
static struct nouveau_fence *
@@ -88,16 +92,23 @@ nouveau_fence_context_del(struct nouveau_fence_chan *fctx)
{
struct nouveau_fence *fence;
- nvif_notify_fini(&fctx->notify);
-
spin_lock_irq(&fctx->lock);
while (!list_empty(&fctx->pending)) {
fence = list_entry(fctx->pending.next, typeof(*fence), head);
- nouveau_fence_signal(fence);
- fence->channel = NULL;
+ if (nouveau_fence_signal(fence))
+ nvif_notify_put(&fctx->notify);
}
spin_unlock_irq(&fctx->lock);
+
+ nvif_notify_fini(&fctx->notify);
+ fctx->dead = 1;
+
+ /*
+ * Ensure that all accesses to fence->channel complete before freeing
+ * the channel.
+ */
+ synchronize_rcu();
}
static void
@@ -112,21 +123,23 @@ nouveau_fence_context_free(struct nouveau_fence_chan *fctx)
kref_put(&fctx->fence_ref, nouveau_fence_context_put);
}
-static void
+static int
nouveau_fence_update(struct nouveau_channel *chan, struct nouveau_fence_chan *fctx)
{
struct nouveau_fence *fence;
-
+ int drop = 0;
u32 seq = fctx->read(chan);
while (!list_empty(&fctx->pending)) {
fence = list_entry(fctx->pending.next, typeof(*fence), head);
if ((int)(seq - fence->base.seqno) < 0)
- return;
+ break;
- nouveau_fence_signal(fence);
+ drop |= nouveau_fence_signal(fence);
}
+
+ return drop;
}
static int
@@ -135,18 +148,21 @@ nouveau_fence_wait_uevent_handler(struct nvif_notify *notify)
struct nouveau_fence_chan *fctx =
container_of(notify, typeof(*fctx), notify);
unsigned long flags;
+ int ret = NVIF_NOTIFY_KEEP;
spin_lock_irqsave(&fctx->lock, flags);
if (!list_empty(&fctx->pending)) {
struct nouveau_fence *fence;
+ struct nouveau_channel *chan;
fence = list_entry(fctx->pending.next, typeof(*fence), head);
- nouveau_fence_update(fence->channel, fctx);
+ chan = rcu_dereference_protected(fence->channel, lockdep_is_held(&fctx->lock));
+ if (nouveau_fence_update(fence->channel, fctx))
+ ret = NVIF_NOTIFY_DROP;
}
spin_unlock_irqrestore(&fctx->lock, flags);
- /* Always return keep here. NVIF refcount is handled with nouveau_fence_update */
- return NVIF_NOTIFY_KEEP;
+ return ret;
}
void
@@ -262,7 +278,10 @@ nouveau_fence_emit(struct nouveau_fence *fence, struct nouveau_channel *chan)
if (!ret) {
fence_get(&fence->base);
spin_lock_irq(&fctx->lock);
- nouveau_fence_update(chan, fctx);
+
+ if (nouveau_fence_update(chan, fctx))
+ nvif_notify_put(&fctx->notify);
+
list_add_tail(&fence->head, &fctx->pending);
spin_unlock_irq(&fctx->lock);
}
@@ -276,13 +295,16 @@ nouveau_fence_done(struct nouveau_fence *fence)
if (fence->base.ops == &nouveau_fence_ops_legacy ||
fence->base.ops == &nouveau_fence_ops_uevent) {
struct nouveau_fence_chan *fctx = nouveau_fctx(fence);
+ struct nouveau_channel *chan;
unsigned long flags;
if (test_bit(FENCE_FLAG_SIGNALED_BIT, &fence->base.flags))
return true;
spin_lock_irqsave(&fctx->lock, flags);
- nouveau_fence_update(fence->channel, fctx);
+ chan = rcu_dereference_protected(fence->channel, lockdep_is_held(&fctx->lock));
+ if (chan && nouveau_fence_update(chan, fctx))
+ nvif_notify_put(&fctx->notify);
spin_unlock_irqrestore(&fctx->lock, flags);
}
return fence_is_signaled(&fence->base);
@@ -387,12 +409,18 @@ nouveau_fence_sync(struct nouveau_bo *nvbo, struct nouveau_channel *chan, bool e
if (fence && (!exclusive || !fobj || !fobj->shared_count)) {
struct nouveau_channel *prev = NULL;
+ bool must_wait = true;
f = nouveau_local_fence(fence, chan->drm);
- if (f)
- prev = f->channel;
+ if (f) {
+ rcu_read_lock();
+ prev = rcu_dereference(f->channel);
+ if (prev && (prev == chan || fctx->sync(f, prev, chan) == 0))
+ must_wait = false;
+ rcu_read_unlock();
+ }
- if (!prev || (prev != chan && (ret = fctx->sync(f, prev, chan))))
+ if (must_wait)
ret = fence_wait(fence, intr);
return ret;
@@ -403,19 +431,22 @@ nouveau_fence_sync(struct nouveau_bo *nvbo, struct nouveau_channel *chan, bool e
for (i = 0; i < fobj->shared_count && !ret; ++i) {
struct nouveau_channel *prev = NULL;
+ bool must_wait = true;
fence = rcu_dereference_protected(fobj->shared[i],
reservation_object_held(resv));
f = nouveau_local_fence(fence, chan->drm);
- if (f)
- prev = f->channel;
+ if (f) {
+ rcu_read_lock();
+ prev = rcu_dereference(f->channel);
+ if (prev && (prev == chan || fctx->sync(f, prev, chan) == 0))
+ must_wait = false;
+ rcu_read_unlock();
+ }
- if (!prev || (prev != chan && (ret = fctx->sync(f, prev, chan))))
+ if (must_wait)
ret = fence_wait(fence, intr);
-
- if (ret)
- break;
}
return ret;
@@ -463,7 +494,7 @@ static const char *nouveau_fence_get_timeline_name(struct fence *f)
struct nouveau_fence *fence = from_fence(f);
struct nouveau_fence_chan *fctx = nouveau_fctx(fence);
- return fence->channel ? fctx->name : "dead channel";
+ return !fctx->dead ? fctx->name : "dead channel";
}
/*
@@ -476,9 +507,16 @@ static bool nouveau_fence_is_signaled(struct fence *f)
{
struct nouveau_fence *fence = from_fence(f);
struct nouveau_fence_chan *fctx = nouveau_fctx(fence);
- struct nouveau_channel *chan = fence->channel;
+ struct nouveau_channel *chan;
+ bool ret = false;
+
+ rcu_read_lock();
+ chan = rcu_dereference(fence->channel);
+ if (chan)
+ ret = (int)(fctx->read(chan) - fence->base.seqno) >= 0;
+ rcu_read_unlock();
- return (int)(fctx->read(chan) - fence->base.seqno) >= 0;
+ return ret;
}
static bool nouveau_fence_no_signaling(struct fence *f)
diff --git a/drivers/gpu/drm/nouveau/nouveau_fence.h b/drivers/gpu/drm/nouveau/nouveau_fence.h
index 943b0b17b1fc..96e461c6f68f 100644
--- a/drivers/gpu/drm/nouveau/nouveau_fence.h
+++ b/drivers/gpu/drm/nouveau/nouveau_fence.h
@@ -14,7 +14,7 @@ struct nouveau_fence {
bool sysmem;
- struct nouveau_channel *channel;
+ struct nouveau_channel __rcu *channel;
unsigned long timeout;
};
@@ -47,7 +47,7 @@ struct nouveau_fence_chan {
char name[32];
struct nvif_notify notify;
- int notify_ref;
+ int notify_ref, dead;
};
struct nouveau_fence_priv {