From: Maarten Lankhorst Date: Mon, 1 Dec 2014 09:11:06 +0000 (+1000) Subject: drm/nouveau: prevent stale fence->channel pointers, and protect with rcu X-Git-Tag: v3.18~15^2~2^2~1 X-Git-Url: https://openfabrics.org/gitweb/?a=commitdiff_plain;h=0ec5f02f0e2c6fe88ba5817790e11fe33ee298a7;p=~emulex%2Finfiniband.git drm/nouveau: prevent stale fence->channel pointers, and protect with rcu Tested-by: Alexandre Courbot Signed-off-by: Ben Skeggs --- diff --git a/drivers/gpu/drm/nouveau/nouveau_fence.c b/drivers/gpu/drm/nouveau/nouveau_fence.c index 515cd9aebb9..f32a434724e 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 943b0b17b1f..96e461c6f68 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 {