[PATCH v1 8/9] drm/panthor: Track the number of mmap on a BO

[Boris Brezillon]

This will be used to order things by reclaimability.

Signed-off-by: Boris Brezillon <boris.brezil...@collabora.com>
---
 drivers/gpu/drm/panthor/panthor_gem.c | 44 +++++++++++++++++++++++++--
 drivers/gpu/drm/panthor/panthor_gem.h |  3 ++
 2 files changed, 45 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/panthor/panthor_gem.c 
b/drivers/gpu/drm/panthor/panthor_gem.c
index 44f05bd957e7..458d22380e96 100644
--- a/drivers/gpu/drm/panthor/panthor_gem.c
+++ b/drivers/gpu/drm/panthor/panthor_gem.c
@@ -484,6 +484,7 @@ static void panthor_gem_print_info(struct drm_printer *p, 
unsigned int indent,
        drm_printf_indent(p, indent, "vmap_use_count=%u\n",
                          refcount_read(&bo->cmap.vaddr_use_count));
        drm_printf_indent(p, indent, "vaddr=%p\n", bo->cmap.vaddr);
+       drm_printf_indent(p, indent, "mmap_count=%u\n", 
refcount_read(&bo->cmap.mmap_count));
 }
 
 static int panthor_gem_pin_locked(struct drm_gem_object *obj)
@@ -600,6 +601,13 @@ static int panthor_gem_mmap(struct drm_gem_object *obj, 
struct vm_area_struct *v
        if (is_cow_mapping(vma->vm_flags))
                return -EINVAL;
 
+       if (!refcount_inc_not_zero(&bo->cmap.mmap_count)) {
+               dma_resv_lock(obj->resv, NULL);
+               if (!refcount_inc_not_zero(&bo->cmap.mmap_count))
+                       refcount_set(&bo->cmap.mmap_count, 1);
+               dma_resv_unlock(obj->resv);
+       }
+
        vm_flags_set(vma, VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP);
        vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
        if (should_map_wc(bo))
@@ -732,10 +740,42 @@ static vm_fault_t panthor_gem_fault(struct vm_fault *vmf)
        return blocking_page_setup(vmf, bo, page_offset, true);
 }
 
+static void panthor_gem_vm_open(struct vm_area_struct *vma)
+{
+       struct panthor_gem_object *bo = to_panthor_bo(vma->vm_private_data);
+
+       /* mmap_count must have been incremented at mmap time, so it can't be
+        * zero here.
+        */
+       if (!drm_gem_is_imported(&bo->base))
+               drm_WARN_ON(bo->base.dev, 
!refcount_inc_not_zero(&bo->cmap.mmap_count));
+
+       drm_gem_vm_open(vma);
+}
+
+static void panthor_gem_vm_close(struct vm_area_struct *vma)
+{
+       struct panthor_gem_object *bo = to_panthor_bo(vma->vm_private_data);
+
+       if (drm_gem_is_imported(&bo->base))
+               goto out;
+
+       if (refcount_dec_not_one(&bo->cmap.mmap_count))
+               goto out;
+
+       dma_resv_lock(bo->base.resv, NULL);
+       if (!refcount_dec_not_one(&bo->cmap.mmap_count))
+               refcount_set(&bo->cmap.mmap_count, 0);
+       dma_resv_unlock(bo->base.resv);
+
+out:
+       drm_gem_object_put(&bo->base);
+}
+
 const struct vm_operations_struct panthor_gem_vm_ops = {
        .fault = panthor_gem_fault,
-       .open = drm_gem_vm_open,
-       .close = drm_gem_vm_close,
+       .open = panthor_gem_vm_open,
+       .close = panthor_gem_vm_close,
 };
 
 static const struct drm_gem_object_funcs panthor_gem_funcs = {
diff --git a/drivers/gpu/drm/panthor/panthor_gem.h 
b/drivers/gpu/drm/panthor/panthor_gem.h
index b66478c9590c..c0a18dca732c 100644
--- a/drivers/gpu/drm/panthor/panthor_gem.h
+++ b/drivers/gpu/drm/panthor/panthor_gem.h
@@ -80,6 +80,9 @@ struct panthor_gem_cpu_map {
 
        /** @vaddr_use_count: Number of active vmap() requests on this GEM */
        refcount_t vaddr_use_count;
+
+       /** @mmap_count: Number of active mmap() requests on this GEM */
+       refcount_t mmap_count;
 };
 
 /**
-- 
2.52.0