diff mbox series

[2/7] drm/vmgfx: Replace kmap_atomic()

Message ID 20210303132711.487711828@linutronix.de (mailing list archive)
State New
Headers show
Series drm, highmem: Cleanup io/kmap_atomic*() usage | expand

Commit Message

Thomas Gleixner March 3, 2021, 1:20 p.m. UTC
From: Thomas Gleixner <tglx@linutronix.de>

There is no reason to disable pagefaults and preemption as a side effect of
kmap_atomic_prot().

Use kmap_local_page_prot() instead and document the reasoning for the
mapping usage with the given pgprot.

Remove the NULL pointer check for the map. These functions return a valid
address for valid pages and the return was bogus anyway as it would have
left preemption and pagefaults disabled.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: VMware Graphics <linux-graphics-maintainer@vmware.com>
Cc: Roland Scheidegger <sroland@vmware.com>
Cc: Zack Rusin <zackr@vmware.com>
Cc: David Airlie <airlied@linux.ie>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: dri-devel@lists.freedesktop.org
---
 drivers/gpu/drm/vmwgfx/vmwgfx_blit.c |   30 ++++++++++++------------------
 1 file changed, 12 insertions(+), 18 deletions(-)

Comments

Zack Rusin March 4, 2021, 6:47 p.m. UTC | #1
> On Mar 3, 2021, at 08:20, Thomas Gleixner <tglx@linutronix.de> wrote:
> 
> From: Thomas Gleixner <tglx@linutronix.de>
> 
> There is no reason to disable pagefaults and preemption as a side effect of
> kmap_atomic_prot().
> 
> Use kmap_local_page_prot() instead and document the reasoning for the
> mapping usage with the given pgprot.
> 
> Remove the NULL pointer check for the map. These functions return a valid
> address for valid pages and the return was bogus anyway as it would have
> left preemption and pagefaults disabled.
> 
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
> Cc: VMware Graphics <linux-graphics-maintainer@vmware.com>
> Cc: Roland Scheidegger <sroland@vmware.com>
> Cc: Zack Rusin <zackr@vmware.com>
> Cc: David Airlie <airlied@linux.ie>
> Cc: Daniel Vetter <daniel@ffwll.ch>
> Cc: dri-devel@lists.freedesktop.org
> ---
> drivers/gpu/drm/vmwgfx/vmwgfx_blit.c |   30 ++++++++++++------------------
> 1 file changed, 12 insertions(+), 18 deletions(-)
> 
> --- a/drivers/gpu/drm/vmwgfx/vmwgfx_blit.c
> +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_blit.c
> @@ -375,12 +375,12 @@ static int vmw_bo_cpu_blit_line(struct v
> 		copy_size = min_t(u32, copy_size, PAGE_SIZE - src_page_offset);
> 
> 		if (unmap_src) {
> -			kunmap_atomic(d->src_addr);
> +			kunmap_local(d->src_addr);
> 			d->src_addr = NULL;
> 		}
> 
> 		if (unmap_dst) {
> -			kunmap_atomic(d->dst_addr);
> +			kunmap_local(d->dst_addr);
> 			d->dst_addr = NULL;
> 		}
> 
> @@ -388,12 +388,8 @@ static int vmw_bo_cpu_blit_line(struct v
> 			if (WARN_ON_ONCE(dst_page >= d->dst_num_pages))
> 				return -EINVAL;
> 
> -			d->dst_addr =
> -				kmap_atomic_prot(d->dst_pages[dst_page],
> -						 d->dst_prot);
> -			if (!d->dst_addr)
> -				return -ENOMEM;
> -
> +			d->dst_addr = kmap_local_page_prot(d->dst_pages[dst_page],
> +							   d->dst_prot);
> 			d->mapped_dst = dst_page;
> 		}
> 
> @@ -401,12 +397,8 @@ static int vmw_bo_cpu_blit_line(struct v
> 			if (WARN_ON_ONCE(src_page >= d->src_num_pages))
> 				return -EINVAL;
> 
> -			d->src_addr =
> -				kmap_atomic_prot(d->src_pages[src_page],
> -						 d->src_prot);
> -			if (!d->src_addr)
> -				return -ENOMEM;
> -
> +			d->src_addr = kmap_local_page_prot(d->src_pages[src_page],
> +							   d->src_prot);
> 			d->mapped_src = src_page;
> 		}
> 		diff->do_cpy(diff, d->dst_addr + dst_page_offset,
> @@ -436,8 +428,10 @@ static int vmw_bo_cpu_blit_line(struct v
>  *
>  * Performs a CPU blit from one buffer object to another avoiding a full
>  * bo vmap which may exhaust- or fragment vmalloc space.
> - * On supported architectures (x86), we're using kmap_atomic which avoids
> - * cross-processor TLB- and cache flushes and may, on non-HIGHMEM systems
> + *
> + * On supported architectures (x86), we're using kmap_local_prot() which
> + * avoids cross-processor TLB- and cache flushes. kmap_local_prot() will
> + * either map a highmem page with the proper pgprot on HIGHMEM=y systems or
>  * reference already set-up mappings.
>  *
>  * Neither of the buffer objects may be placed in PCI memory
> @@ -500,9 +494,9 @@ int vmw_bo_cpu_blit(struct ttm_buffer_ob
> 	}
> out:
> 	if (d.src_addr)
> -		kunmap_atomic(d.src_addr);
> +		kunmap_local(d.src_addr);
> 	if (d.dst_addr)
> -		kunmap_atomic(d.dst_addr);
> +		kunmap_local(d.dst_addr);
> 
> 	return ret;
> }


Looks good. Thanks.

Reviewed-by: Zack Rusin <zackr@vmware.com>

z
Roland Scheidegger March 5, 2021, 3:35 p.m. UTC | #2
On 03.03.21 14:20, Thomas Gleixner wrote:
> From: Thomas Gleixner <tglx@linutronix.de>
> 
> There is no reason to disable pagefaults and preemption as a side effect of
> kmap_atomic_prot().
> 
> Use kmap_local_page_prot() instead and document the reasoning for the
> mapping usage with the given pgprot.
> 
> Remove the NULL pointer check for the map. These functions return a valid
> address for valid pages and the return was bogus anyway as it would have
> left preemption and pagefaults disabled.
> 
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
> Cc: VMware Graphics <linux-graphics-maintainer@vmware.com>
> Cc: Roland Scheidegger <sroland@vmware.com>
> Cc: Zack Rusin <zackr@vmware.com>
> Cc: David Airlie <airlied@linux.ie>
> Cc: Daniel Vetter <daniel@ffwll.ch>
> Cc: dri-devel@lists.freedesktop.org
> ---
>  drivers/gpu/drm/vmwgfx/vmwgfx_blit.c |   30 ++++++++++++------------------
>  1 file changed, 12 insertions(+), 18 deletions(-)
> 
> --- a/drivers/gpu/drm/vmwgfx/vmwgfx_blit.c
> +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_blit.c
> @@ -375,12 +375,12 @@ static int vmw_bo_cpu_blit_line(struct v
>  		copy_size = min_t(u32, copy_size, PAGE_SIZE - src_page_offset);
>  
>  		if (unmap_src) {
> -			kunmap_atomic(d->src_addr);
> +			kunmap_local(d->src_addr);
>  			d->src_addr = NULL;
>  		}
>  
>  		if (unmap_dst) {
> -			kunmap_atomic(d->dst_addr);
> +			kunmap_local(d->dst_addr);
>  			d->dst_addr = NULL;
>  		}
>  
> @@ -388,12 +388,8 @@ static int vmw_bo_cpu_blit_line(struct v
>  			if (WARN_ON_ONCE(dst_page >= d->dst_num_pages))
>  				return -EINVAL;
>  
> -			d->dst_addr =
> -				kmap_atomic_prot(d->dst_pages[dst_page],
> -						 d->dst_prot);
> -			if (!d->dst_addr)
> -				return -ENOMEM;
> -
> +			d->dst_addr = kmap_local_page_prot(d->dst_pages[dst_page],
> +							   d->dst_prot);
>  			d->mapped_dst = dst_page;
>  		}
>  
> @@ -401,12 +397,8 @@ static int vmw_bo_cpu_blit_line(struct v
>  			if (WARN_ON_ONCE(src_page >= d->src_num_pages))
>  				return -EINVAL;
>  
> -			d->src_addr =
> -				kmap_atomic_prot(d->src_pages[src_page],
> -						 d->src_prot);
> -			if (!d->src_addr)
> -				return -ENOMEM;
> -
> +			d->src_addr = kmap_local_page_prot(d->src_pages[src_page],
> +							   d->src_prot);
>  			d->mapped_src = src_page;
>  		}
>  		diff->do_cpy(diff, d->dst_addr + dst_page_offset,
> @@ -436,8 +428,10 @@ static int vmw_bo_cpu_blit_line(struct v
>   *
>   * Performs a CPU blit from one buffer object to another avoiding a full
>   * bo vmap which may exhaust- or fragment vmalloc space.
> - * On supported architectures (x86), we're using kmap_atomic which avoids
> - * cross-processor TLB- and cache flushes and may, on non-HIGHMEM systems
> + *
> + * On supported architectures (x86), we're using kmap_local_prot() which
> + * avoids cross-processor TLB- and cache flushes. kmap_local_prot() will
> + * either map a highmem page with the proper pgprot on HIGHMEM=y systems or
>   * reference already set-up mappings.
>   *
>   * Neither of the buffer objects may be placed in PCI memory
> @@ -500,9 +494,9 @@ int vmw_bo_cpu_blit(struct ttm_buffer_ob
>  	}
>  out:
>  	if (d.src_addr)
> -		kunmap_atomic(d.src_addr);
> +		kunmap_local(d.src_addr);
>  	if (d.dst_addr)
> -		kunmap_atomic(d.dst_addr);
> +		kunmap_local(d.dst_addr);
>  
>  	return ret;
>  }
> 
> 

Seems reasonable to me.
Reviewed-by: Roland Scheidegger <sroland@vmware.com>
diff mbox series

Patch

--- a/drivers/gpu/drm/vmwgfx/vmwgfx_blit.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_blit.c
@@ -375,12 +375,12 @@  static int vmw_bo_cpu_blit_line(struct v
 		copy_size = min_t(u32, copy_size, PAGE_SIZE - src_page_offset);
 
 		if (unmap_src) {
-			kunmap_atomic(d->src_addr);
+			kunmap_local(d->src_addr);
 			d->src_addr = NULL;
 		}
 
 		if (unmap_dst) {
-			kunmap_atomic(d->dst_addr);
+			kunmap_local(d->dst_addr);
 			d->dst_addr = NULL;
 		}
 
@@ -388,12 +388,8 @@  static int vmw_bo_cpu_blit_line(struct v
 			if (WARN_ON_ONCE(dst_page >= d->dst_num_pages))
 				return -EINVAL;
 
-			d->dst_addr =
-				kmap_atomic_prot(d->dst_pages[dst_page],
-						 d->dst_prot);
-			if (!d->dst_addr)
-				return -ENOMEM;
-
+			d->dst_addr = kmap_local_page_prot(d->dst_pages[dst_page],
+							   d->dst_prot);
 			d->mapped_dst = dst_page;
 		}
 
@@ -401,12 +397,8 @@  static int vmw_bo_cpu_blit_line(struct v
 			if (WARN_ON_ONCE(src_page >= d->src_num_pages))
 				return -EINVAL;
 
-			d->src_addr =
-				kmap_atomic_prot(d->src_pages[src_page],
-						 d->src_prot);
-			if (!d->src_addr)
-				return -ENOMEM;
-
+			d->src_addr = kmap_local_page_prot(d->src_pages[src_page],
+							   d->src_prot);
 			d->mapped_src = src_page;
 		}
 		diff->do_cpy(diff, d->dst_addr + dst_page_offset,
@@ -436,8 +428,10 @@  static int vmw_bo_cpu_blit_line(struct v
  *
  * Performs a CPU blit from one buffer object to another avoiding a full
  * bo vmap which may exhaust- or fragment vmalloc space.
- * On supported architectures (x86), we're using kmap_atomic which avoids
- * cross-processor TLB- and cache flushes and may, on non-HIGHMEM systems
+ *
+ * On supported architectures (x86), we're using kmap_local_prot() which
+ * avoids cross-processor TLB- and cache flushes. kmap_local_prot() will
+ * either map a highmem page with the proper pgprot on HIGHMEM=y systems or
  * reference already set-up mappings.
  *
  * Neither of the buffer objects may be placed in PCI memory
@@ -500,9 +494,9 @@  int vmw_bo_cpu_blit(struct ttm_buffer_ob
 	}
 out:
 	if (d.src_addr)
-		kunmap_atomic(d.src_addr);
+		kunmap_local(d.src_addr);
 	if (d.dst_addr)
-		kunmap_atomic(d.dst_addr);
+		kunmap_local(d.dst_addr);
 
 	return ret;
 }