Revert the move of lost_context setting to UNLOCK_HARDWARE that was done in the

last commit.  I've been convinced by keithw that it's sufficient, and put a note
in the code about it.

Close another race for state in the Clear functions.  I made the situation worse
in my last commit, but this should fix things.  Might be a slight performance
hit, which could be regained by splitting the R*_FIREVERTICES calls in r*Clear
up so that the EmitState doesn't happen in a separate new cmdbuf.

src/mesa/drivers/dri/r200/r200_ioctl.c

@@ -132,6 +132,19 @@ int r200FlushCmdBufLocked( r200ContextPtr rmesa, const char * caller )
    rmesa->store.statenr = 0;
    rmesa->store.cmd_used = 0;
    rmesa->dma.nr_released_bufs = 0;
+   /* Set lost_context so that the first state emit on the new buffer is a full
+    * one.  This is because the context might get lost while preparing the next
+    * buffer, and when we lock and find out, we don't have the information to
+    * recreate the state.  This function should always be called before the new
+    * buffer is begun, so it's sufficient to just set lost_context here.
+    *
+    * The alternative to this would be to copy out the state on unlock
+    * (approximately) and if we did lose the context, dispatch a cmdbuf to reset
+    * the state to that old copy before continuing with the accumulated command
+    * buffer.
+    */
+   rmesa->lost_context = 1;
+
    return ret;
 }
 
@@ -563,9 +576,6 @@ static void r200Clear( GLcontext *ctx, GLbitfield mask, GLboolean all,
 	 return;
    }
 
-   /* Need to cope with lostcontext here as kernel relies on
-    * some residual state:
-    */
    R200_FIREVERTICES( rmesa ); 
 
    if ( mask & DD_FRONT_LEFT_BIT ) {
@@ -603,6 +613,13 @@ static void r200Clear( GLcontext *ctx, GLbitfield mask, GLboolean all,
    cx += dPriv->x;
    cy  = dPriv->y + dPriv->h - cy - ch;
 
+   /* We have to emit state along with the clear, since the kernel relies on
+    * some of it.  The EmitState that was above R200_FIREVERTICES was an
+    * attempt to do that, except that another context may come in and cause us
+    * to lose our context while we're unlocked.
+    */
+   r200EmitState( rmesa );
+
    LOCK_HARDWARE( rmesa );
 
    /* Throttle the number of clear ioctls we do.
@@ -635,6 +652,8 @@ static void r200Clear( GLcontext *ctx, GLbitfield mask, GLboolean all,
       }
    }
 
+   /* Send current state to the hardware */
+   r200FlushCmdBufLocked( rmesa, __FUNCTION__ );
 
    for ( i = 0 ; i < dPriv->numClipRects ; ) {
       GLint nr = MIN2( i + RADEON_NR_SAREA_CLIPRECTS, dPriv->numClipRects );

src/mesa/drivers/dri/r200/r200_lock.h

@@ -98,23 +98,12 @@ extern int prevLockLine;
       DEBUG_LOCK();						\
    } while (0)
 
-/* Unlock the hardware.  We must assume that state has been lost when we unlock,
- * because when we next grab the lock (to emit an accumulated cmdbuf), we don't
- * have the information to recreate the context state as of the last unlock in
- * in the case that we did lose the context state.
- *
- * The alternative to this would be to copy out the state on unlock
- * (approximately) and if we did lose the context, dispatch a cmdbuf to reset
- * the state to that old copy before continuing with the accumulated command
- * buffer.
- */
 #define UNLOCK_HARDWARE( rmesa )					\
    do {									\
       DRM_UNLOCK( rmesa->dri.fd,					\
 		  rmesa->dri.hwLock,					\
 		  rmesa->dri.hwContext );				\
       DEBUG_RESET();							\
-      rmesa->lost_context = GL_TRUE;					\
    } while (0)
 
 #endif

src/mesa/drivers/dri/radeon/radeon_ioctl.c

@@ -544,6 +544,19 @@ static int radeonFlushCmdBufLocked( radeonContextPtr rmesa,
    rmesa->store.statenr = 0;
    rmesa->store.cmd_used = 0;
    rmesa->dma.nr_released_bufs = 0;
+   /* Set lost_context so that the first state emit on the new buffer is a full
+    * one.  This is because the context might get lost while preparing the next
+    * buffer, and when we lock and find out, we don't have the information to
+    * recreate the state.  This function should always be called before the new
+    * buffer is begun, so it's sufficient to just set lost_context here.
+    *
+    * The alternative to this would be to copy out the state on unlock
+    * (approximately) and if we did lose the context, dispatch a cmdbuf to reset
+    * the state to that old copy before continuing with the accumulated command
+    * buffer.
+    */
+   rmesa->lost_context = 1;
+
    return ret;
 }
 
@@ -977,9 +990,6 @@ static void radeonClear( GLcontext *ctx, GLbitfield mask, GLboolean all,
 	       __FUNCTION__, all, cx, cy, cw, ch );
    }
 
-   /* Need to cope with lostcontext here as kernel relies on
-    * some residual state:
-    */
    RADEON_FIREVERTICES( rmesa ); 
 
    if ( mask & DD_FRONT_LEFT_BIT ) {
@@ -1018,6 +1028,13 @@ static void radeonClear( GLcontext *ctx, GLbitfield mask, GLboolean all,
    cx += dPriv->x;
    cy  = dPriv->y + dPriv->h - cy - ch;
 
+   /* We have to emit state along with the clear, since the kernel relies on
+    * some of it.  The EmitState that was above RADEON_FIREVERTICES was an
+    * attempt to do that, except that another context may come in and cause us
+    * to lose our context while we're unlocked.
+    */
+   radeonEmitState( rmesa );
+
    LOCK_HARDWARE( rmesa );
 
    /* Throttle the number of clear ioctls we do.
@@ -1059,6 +1076,9 @@ static void radeonClear( GLcontext *ctx, GLbitfield mask, GLboolean all,
       }
    }
 
+   /* Send current state to the hardware */
+   radeonFlushCmdBufLocked( rmesa, __FUNCTION__ );
+
    for ( i = 0 ; i < dPriv->numClipRects ; ) {
       GLint nr = MIN2( i + RADEON_NR_SAREA_CLIPRECTS, dPriv->numClipRects );
       drm_clip_rect_t *box = dPriv->pClipRects;

src/mesa/drivers/dri/radeon/radeon_lock.h

@@ -99,23 +99,12 @@ extern int prevLockLine;
       DEBUG_LOCK();						\
    } while (0)
 
-/* Unlock the hardware.  We must assume that state has been lost when we unlock,
- * because when we next grab the lock (to emit an accumulated cmdbuf), we don't
- * have the information to recreate the context state as of the last unlock in
- * in the case that we did lose the context state.
- *
- * The alternative to this would be to copy out the state on unlock
- * (approximately) and if we did lose the context, dispatch a cmdbuf to reset
- * the state to that old copy before continuing with the accumulated command
- * buffer.
- */
 #define UNLOCK_HARDWARE( rmesa )					\
    do {									\
       DRM_UNLOCK( rmesa->dri.fd,					\
 		  rmesa->dri.hwLock,					\
 		  rmesa->dri.hwContext );				\
       DEBUG_RESET();							\
-      rmesa->lost_context = GL_TRUE;					\
    } while (0)
 
 #endif