svn commit: r244793 - in user/attilio/membarclean/dev: drm drm2 netmap virtio

[Konstantin Belousov]

On Fri, Dec 28, 2012 at 10:18:41PM +0000, Attilio Rao wrote:
> Author: attilio
> Date: Fri Dec 28 22:18:41 2012
> New Revision: 244793
> URL: http://svnweb.freebsd.org/changeset/base/244793
> 
> Log:
>   - Remove rmb() usage from netmap and replace it with intended operation
>     to do actual memory fetching reads.
>   - GC unused DRM_WRITEMEMORYBARRIER() from drm and drm2.
>   - Use atomic_load_acq_*() in virtio and drm2 in places that don't need
>     to use rmb().
>   
>   All these changes remove completely rmb() from MI code, with the
>   exception of cxgbe which will be hammered in a followup commit.
> 
> Modified:
>   user/attilio/membarclean/dev/drm/drmP.h
>   user/attilio/membarclean/dev/drm2/drmP.h
>   user/attilio/membarclean/dev/drm2/drm_atomic.h
>   user/attilio/membarclean/dev/drm2/drm_irq.c
>   user/attilio/membarclean/dev/netmap/netmap.c
>   user/attilio/membarclean/dev/virtio/virtqueue.c
> 
> Modified: user/attilio/membarclean/dev/drm/drmP.h
> ==============================================================================
> --- user/attilio/membarclean/dev/drm/drmP.h	Fri Dec 28 22:06:50 2012	(r244792)
> +++ user/attilio/membarclean/dev/drm/drmP.h	Fri Dec 28 22:18:41 2012	(r244793)
> @@ -241,11 +241,9 @@ typedef u_int32_t u32;
>  typedef u_int16_t u16;
>  typedef u_int8_t u8;
>  
> -/* DRM_READMEMORYBARRIER() prevents reordering of reads.
> - * DRM_WRITEMEMORYBARRIER() prevents reordering of writes.
> +/* DRM_WRITEMEMORYBARRIER() prevents reordering of writes.
>   * DRM_MEMORYBARRIER() prevents reordering of reads and writes.
>   */
> -#define DRM_READMEMORYBARRIER()		rmb()
>  #define DRM_WRITEMEMORYBARRIER()	wmb()
>  #define DRM_MEMORYBARRIER()		mb()
>  
> 
> Modified: user/attilio/membarclean/dev/drm2/drmP.h
> ==============================================================================
> --- user/attilio/membarclean/dev/drm2/drmP.h	Fri Dec 28 22:06:50 2012	(r244792)
> +++ user/attilio/membarclean/dev/drm2/drmP.h	Fri Dec 28 22:18:41 2012	(r244793)
> @@ -263,11 +263,9 @@ typedef int32_t s32;
>  typedef int16_t s16;
>  typedef int8_t s8;
>  
> -/* DRM_READMEMORYBARRIER() prevents reordering of reads.
> - * DRM_WRITEMEMORYBARRIER() prevents reordering of writes.
> +/* DRM_WRITEMEMORYBARRIER() prevents reordering of writes.
>   * DRM_MEMORYBARRIER() prevents reordering of reads and writes.
>   */
> -#define DRM_READMEMORYBARRIER()		rmb()
>  #define DRM_WRITEMEMORYBARRIER()	wmb()
>  #define DRM_MEMORYBARRIER()		mb()
>  
> 
> Modified: user/attilio/membarclean/dev/drm2/drm_atomic.h
> ==============================================================================
> --- user/attilio/membarclean/dev/drm2/drm_atomic.h	Fri Dec 28 22:06:50 2012	(r244792)
> +++ user/attilio/membarclean/dev/drm2/drm_atomic.h	Fri Dec 28 22:18:41 2012	(r244793)
> @@ -38,6 +38,7 @@ typedef u_int32_t atomic_t;
>  
>  #define atomic_set(p, v)	(*(p) = (v))
>  #define atomic_read(p)		(*(p))
> +#define atomic_read_acq(p)	atomic_load_acq_int(p)
>  #define atomic_inc(p)		atomic_add_int(p, 1)
>  #define atomic_dec(p)		atomic_subtract_int(p, 1)
>  #define atomic_add(n, p)	atomic_add_int(p, n)
> 
> Modified: user/attilio/membarclean/dev/drm2/drm_irq.c
> ==============================================================================
> --- user/attilio/membarclean/dev/drm2/drm_irq.c	Fri Dec 28 22:06:50 2012	(r244792)
> +++ user/attilio/membarclean/dev/drm2/drm_irq.c	Fri Dec 28 22:18:41 2012	(r244793)
> @@ -701,8 +701,7 @@ u32 drm_vblank_count_and_time(struct drm
>  	do {
>  		cur_vblank = atomic_read(&dev->_vblank_count[crtc]);
>  		*vblanktime = vblanktimestamp(dev, crtc, cur_vblank);
> -		rmb();
> -	} while (cur_vblank != atomic_read(&dev->_vblank_count[crtc]));
> +	} while (cur_vblank != atomic_read_acq(&dev->_vblank_count[crtc]));
>  
>  	return cur_vblank;
>  }

The drm/drm2 is the contributed code, maintained outside the tree, and I
explicitely decided to keep the original approach. I will appreciate if
this would be left as it is.
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