sna: Handle asynchronous signals from threads

By killing the threads and leaking their allocations - marginally
preferrable to losing the entire Xserver.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

5 files changed, 88 insertions, 51 deletions

diff --git a/src/sna/sna.h b/src/sna/sna.h
index 1b0a4e58..0b5de8e5 100644
--- a/src/sna/sna.h
+++ b/src/sna/sna.h
@@ -1017,6 +1017,7 @@ void sna_threads_init(void);
 int sna_use_threads (int width, int height, int threshold);
 void sna_threads_run(void (*func)(void *arg), void *arg);
 void sna_threads_wait(void);
+void sna_threads_kill(void);
 
 void sna_image_composite(pixman_op_t        op,
 			 pixman_image_t    *src,
diff --git a/src/sna/sna_threads.c b/src/sna/sna_threads.c
index 6627cbda..8f554965 100644
--- a/src/sna/sna_threads.c
+++ b/src/sna/sna_threads.c
@@ -205,6 +205,22 @@ void sna_threads_wait(void)
 	}
 }
 
+void sna_threads_kill(void)
+{
+	int n;
+
+	ERR(("kill %d threads\n", max_threads));
+	assert(max_threads > 0);
+
+	for (n = 0; n < max_threads; n++)
+		pthread_cancel(threads[n].thread);
+
+	for (n = 0; n < max_threads; n++)
+		pthread_join(threads[n].thread, NULL);
+
+	max_threads = 0;
+}
+
 int sna_use_threads(int width, int height, int threshold)
 {
 	int num_threads;
diff --git a/src/sna/sna_trapezoids_boxes.c b/src/sna/sna_trapezoids_boxes.c
index 6d81da68..d6f0c371 100644
--- a/src/sna/sna_trapezoids_boxes.c
+++ b/src/sna/sna_trapezoids_boxes.c
@@ -1181,19 +1181,23 @@ composite_unaligned_boxes_inplace(struct sna *sna,
 			dy = (clip.extents.y2 - clip.extents.y1 + num_threads - 1) / num_threads;
 			num_threads = (clip.extents.y2 - clip.extents.y1 + dy - 1) / dy;
 
-			for (i = 1; i < num_threads; i++) {
-				thread[i] = thread[0];
-				thread[i].y1 = y;
-				thread[i].y2 = y += dy;
-				sna_threads_run(rectilinear_inplace_thread, &thread[i]);
-			}
+			if (sigtrap_get() == 0) {
+				for (i = 1; i < num_threads; i++) {
+					thread[i] = thread[0];
+					thread[i].y1 = y;
+					thread[i].y2 = y += dy;
+					sna_threads_run(rectilinear_inplace_thread, &thread[i]);
+				}
 
-			assert(y < clip.extents.y2);
-			thread[0].y1 = y;
-			thread[0].y2 = clip.extents.y2;
-			rectilinear_inplace_thread(&thread[0]);
+				assert(y < clip.extents.y2);
+				thread[0].y1 = y;
+				thread[0].y2 = clip.extents.y2;
+				rectilinear_inplace_thread(&thread[0]);
 
-			sna_threads_wait();
+				sna_threads_wait();
+				sigtrap_put();
+			} else
+				sna_threads_kill();
 
 			pixman_image_unref(thread[0].dst);
 			pixman_image_unref(thread[0].src);
diff --git a/src/sna/sna_trapezoids_imprecise.c b/src/sna/sna_trapezoids_imprecise.c
index ddf52c2c..93823bb0 100644
--- a/src/sna/sna_trapezoids_imprecise.c
+++ b/src/sna/sna_trapezoids_imprecise.c
@@ -2851,19 +2851,23 @@ trapezoid_span_inplace__x8r8g8b8(CARD8 op,
 		h = (h + num_threads - 1) / num_threads;
 		num_threads -= (num_threads-1) * h >= region.extents.y2 - region.extents.y1;
 
-		for (n = 1; n < num_threads; n++) {
-			threads[n] = threads[0];
-			threads[n].extents.y1 = y;
-			threads[n].extents.y2 = y += h;
+		if (sigtrap_get() == 0) {
+			for (n = 1; n < num_threads; n++) {
+				threads[n] = threads[0];
+				threads[n].extents.y1 = y;
+				threads[n].extents.y2 = y += h;
 
-			sna_threads_run(inplace_x8r8g8b8_thread, &threads[n]);
-		}
+				sna_threads_run(inplace_x8r8g8b8_thread, &threads[n]);
+			}
 
-		assert(y < threads[0].extents.y2);
-		threads[0].extents.y1 = y;
-		inplace_x8r8g8b8_thread(&threads[0]);
+			assert(y < threads[0].extents.y2);
+			threads[0].extents.y1 = y;
+			inplace_x8r8g8b8_thread(&threads[0]);
 
-		sna_threads_wait();
+			sna_threads_wait();
+			sigtrap_put();
+		} else
+			sna_threads_kill(); /* leaks thread allocations */
 	}
 
 	return true;
@@ -3125,19 +3129,23 @@ imprecise_trapezoid_span_inplace(struct sna *sna,
 		h = (h + num_threads - 1) / num_threads;
 		num_threads -= (num_threads-1) * h >= region.extents.y2 - region.extents.y1;
 
-		for (n = 1; n < num_threads; n++) {
-			threads[n] = threads[0];
-			threads[n].extents.y1 = y;
-			threads[n].extents.y2 = y += h;
+		if (sigtrap_get() == 0) {
+			for (n = 1; n < num_threads; n++) {
+				threads[n] = threads[0];
+				threads[n].extents.y1 = y;
+				threads[n].extents.y2 = y += h;
 
-			sna_threads_run(inplace_thread, &threads[n]);
-		}
+				sna_threads_run(inplace_thread, &threads[n]);
+			}
 
-		assert(y < threads[0].extents.y2);
-		threads[0].extents.y1 = y;
-		inplace_thread(&threads[0]);
+			assert(y < threads[0].extents.y2);
+			threads[0].extents.y1 = y;
+			inplace_thread(&threads[0]);
 
-		sna_threads_wait();
+			sna_threads_wait();
+			sigtrap_put();
+		} else
+			sna_threads_kill(); /* leaks thread allocations */
 	}
 
 	return true;
diff --git a/src/sna/sna_trapezoids_precise.c b/src/sna/sna_trapezoids_precise.c
index e5bab16b..bc0a7e7c 100644
--- a/src/sna/sna_trapezoids_precise.c
+++ b/src/sna/sna_trapezoids_precise.c
@@ -2849,19 +2849,23 @@ trapezoid_span_inplace__x8r8g8b8(CARD8 op,
 		h = (h + num_threads - 1) / num_threads;
 		num_threads -= (num_threads-1) * h >= region.extents.y2 - region.extents.y1;
 
-		for (n = 1; n < num_threads; n++) {
-			threads[n] = threads[0];
-			threads[n].extents.y1 = y;
-			threads[n].extents.y2 = y += h;
+		if (sigtrap_get() == 0) {
+			for (n = 1; n < num_threads; n++) {
+				threads[n] = threads[0];
+				threads[n].extents.y1 = y;
+				threads[n].extents.y2 = y += h;
 
-			sna_threads_run(inplace_x8r8g8b8_thread, &threads[n]);
-		}
+				sna_threads_run(inplace_x8r8g8b8_thread, &threads[n]);
+			}
 
-		assert(y < threads[0].extents.y2);
-		threads[0].extents.y1 = y;
-		inplace_x8r8g8b8_thread(&threads[0]);
+			assert(y < threads[0].extents.y2);
+			threads[0].extents.y1 = y;
+			inplace_x8r8g8b8_thread(&threads[0]);
 
-		sna_threads_wait();
+			sna_threads_wait();
+			sigtrap_put();
+		} else
+			sna_threads_kill(); /* leaks thread allocations */
 	}
 
 	return true;
@@ -3124,19 +3128,23 @@ precise_trapezoid_span_inplace(struct sna *sna,
 		h = (h + num_threads - 1) / num_threads;
 		num_threads -= (num_threads-1) * h >= region.extents.y2 - region.extents.y1;
 
-		for (n = 1; n < num_threads; n++) {
-			threads[n] = threads[0];
-			threads[n].extents.y1 = y;
-			threads[n].extents.y2 = y += h;
+		if (sigtrap_get() == 0) {
+			for (n = 1; n < num_threads; n++) {
+				threads[n] = threads[0];
+				threads[n].extents.y1 = y;
+				threads[n].extents.y2 = y += h;
 
-			sna_threads_run(inplace_thread, &threads[n]);
-		}
+				sna_threads_run(inplace_thread, &threads[n]);
+			}
 
-		assert(y < threads[0].extents.y2);
-		threads[0].extents.y1 = y;
-		inplace_thread(&threads[0]);
+			assert(y < threads[0].extents.y2);
+			threads[0].extents.y1 = y;
+			inplace_thread(&threads[0]);
 
-		sna_threads_wait();
+			sna_threads_wait();
+			sigtrap_put();
+		} else
+			sna_threads_kill(); /* leaks thread allocations */
 	}
 
 	return true;