Re: [PATCH] drm/nouveau: gk20a: Turn instmem lock into mutex

[Thierry Reding <thierry.reding@gmail.com>]

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On Mon, Jan 30, 2017 at 09:03:07PM +0100, Thierry Reding wrote:
> From: Thierry Reding <treding@nvidia.com>
> 
> The gk20a implementation of instance memory uses vmap()/vunmap() to map
> memory regions into the kernel's virtual address space. These functions
> may sleep, so protecting them by a spin lock is not safe. This triggers
> a warning if the DEBUG_ATOMIC_SLEEP Kconfig option is enabled. Fix this
> by using a mutex instead.
> 
> Signed-off-by: Thierry Reding <treding@nvidia.com>
> ---
>  drivers/gpu/drm/nouveau/nvkm/subdev/instmem/gk20a.c | 19 ++++++++-----------
>  1 file changed, 8 insertions(+), 11 deletions(-)

Alex, could you take a look at this?

Thanks,
Thierry

> diff --git a/drivers/gpu/drm/nouveau/nvkm/subdev/instmem/gk20a.c b/drivers/gpu/drm/nouveau/nvkm/subdev/instmem/gk20a.c
> index a6a7fa0d7679..7f5244d57d2f 100644
> --- a/drivers/gpu/drm/nouveau/nvkm/subdev/instmem/gk20a.c
> +++ b/drivers/gpu/drm/nouveau/nvkm/subdev/instmem/gk20a.c
> @@ -94,7 +94,7 @@ struct gk20a_instmem {
>  	struct nvkm_instmem base;
>  
>  	/* protects vaddr_* and gk20a_instobj::vaddr* */
> -	spinlock_t lock;
> +	struct mutex lock;
>  
>  	/* CPU mappings LRU */
>  	unsigned int vaddr_use;
> @@ -184,11 +184,10 @@ gk20a_instobj_acquire_iommu(struct nvkm_memory *memory)
>  	struct gk20a_instmem *imem = node->base.imem;
>  	struct nvkm_ltc *ltc = imem->base.subdev.device->ltc;
>  	const u64 size = nvkm_memory_size(memory);
> -	unsigned long flags;
>  
>  	nvkm_ltc_flush(ltc);
>  
> -	spin_lock_irqsave(&imem->lock, flags);
> +	mutex_lock(&imem->lock);
>  
>  	if (node->base.vaddr) {
>  		if (!node->use_cpt) {
> @@ -216,7 +215,7 @@ gk20a_instobj_acquire_iommu(struct nvkm_memory *memory)
>  
>  out:
>  	node->use_cpt++;
> -	spin_unlock_irqrestore(&imem->lock, flags);
> +	mutex_unlock(&imem->lock);
>  
>  	return node->base.vaddr;
>  }
> @@ -239,9 +238,8 @@ gk20a_instobj_release_iommu(struct nvkm_memory *memory)
>  	struct gk20a_instobj_iommu *node = gk20a_instobj_iommu(memory);
>  	struct gk20a_instmem *imem = node->base.imem;
>  	struct nvkm_ltc *ltc = imem->base.subdev.device->ltc;
> -	unsigned long flags;
>  
> -	spin_lock_irqsave(&imem->lock, flags);
> +	mutex_lock(&imem->lock);
>  
>  	/* we should at least have one user to release... */
>  	if (WARN_ON(node->use_cpt == 0))
> @@ -252,7 +250,7 @@ gk20a_instobj_release_iommu(struct nvkm_memory *memory)
>  		list_add_tail(&node->vaddr_node, &imem->vaddr_lru);
>  
>  out:
> -	spin_unlock_irqrestore(&imem->lock, flags);
> +	mutex_unlock(&imem->lock);
>  
>  	wmb();
>  	nvkm_ltc_invalidate(ltc);
> @@ -306,19 +304,18 @@ gk20a_instobj_dtor_iommu(struct nvkm_memory *memory)
>  	struct gk20a_instmem *imem = node->base.imem;
>  	struct device *dev = imem->base.subdev.device->dev;
>  	struct nvkm_mm_node *r;
> -	unsigned long flags;
>  	int i;
>  
>  	if (unlikely(list_empty(&node->base.mem.regions)))
>  		goto out;
>  
> -	spin_lock_irqsave(&imem->lock, flags);
> +	mutex_lock(&imem->lock);
>  
>  	/* vaddr has already been recycled */
>  	if (node->base.vaddr)
>  		gk20a_instobj_iommu_recycle_vaddr(node);
>  
> -	spin_unlock_irqrestore(&imem->lock, flags);
> +	mutex_unlock(&imem->lock);
>  
>  	r = list_first_entry(&node->base.mem.regions, struct nvkm_mm_node,
>  			     rl_entry);
> @@ -580,7 +577,7 @@ gk20a_instmem_new(struct nvkm_device *device, int index,
>  	if (!(imem = kzalloc(sizeof(*imem), GFP_KERNEL)))
>  		return -ENOMEM;
>  	nvkm_instmem_ctor(&gk20a_instmem, device, index, &imem->base);
> -	spin_lock_init(&imem->lock);
> +	mutex_init(&imem->lock);
>  	*pimem = &imem->base;
>  
>  	/* do not allow more than 1MB of CPU-mapped instmem */
> -- 
> 2.11.0
> 

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