Module Name: src
Committed By: riastradh
Date: Sun Dec 19 12:26:22 UTC 2021
Modified Files:
src/sys/external/bsd/drm2/linux: linux_dma_resv.c
Log Message:
drm: Make sure to check read ticket after reading shared fences.
Not entirely sure it was a bug not to do that, but let's make it easy
to prove that we got a consistent snapshot of the whole picture.
To generate a diff of this commit:
cvs rdiff -u -r1.13 -r1.14 src/sys/external/bsd/drm2/linux/linux_dma_resv.c
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/sys/external/bsd/drm2/linux/linux_dma_resv.c
diff -u src/sys/external/bsd/drm2/linux/linux_dma_resv.c:1.13 src/sys/external/bsd/drm2/linux/linux_dma_resv.c:1.14
--- src/sys/external/bsd/drm2/linux/linux_dma_resv.c:1.13 Sun Dec 19 12:26:13 2021
+++ src/sys/external/bsd/drm2/linux/linux_dma_resv.c Sun Dec 19 12:26:22 2021
@@ -1,4 +1,4 @@
-/* $NetBSD: linux_dma_resv.c,v 1.13 2021/12/19 12:26:13 riastradh Exp $ */
+/* $NetBSD: linux_dma_resv.c,v 1.14 2021/12/19 12:26:22 riastradh Exp $ */
/*-
* Copyright (c) 2018 The NetBSD Foundation, Inc.
@@ -30,7 +30,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: linux_dma_resv.c,v 1.13 2021/12/19 12:26:13 riastradh Exp $");
+__KERNEL_RCSID(0, "$NetBSD: linux_dma_resv.c,v 1.14 2021/12/19 12:26:22 riastradh Exp $");
#include <sys/param.h>
#include <sys/poll.h>
@@ -813,10 +813,14 @@ top: KASSERT(fence == NULL);
* and record the number of elements. Could safely use
* memcpy here, because even if we race with a writer
* it'll invalidate the read ticket and we'll start
- * ove, but atomic_load in a loop will pacify kcsan.
+ * over, but atomic_load in a loop will pacify kcsan.
*/
for (i = 0; i < shared_count; i++)
shared[i] = atomic_load_relaxed(&list->shared[i]);
+
+ /* If anything changed while we were copying, restart. */
+ if (!dma_resv_read_valid(robj, &ticket))
+ goto restart;
}
/* If there is an exclusive fence, grab it. */
@@ -910,6 +914,10 @@ top: KASSERT(fence == NULL);
dst_list->shared[dst_list->shared_count++] = fence;
fence = NULL;
}
+
+ /* If anything changed while we were copying, restart. */
+ if (!dma_resv_read_valid(src_robj, &read_ticket))
+ goto restart;
}
/* Get the exclusive fence. */
@@ -1031,6 +1039,10 @@ top: KASSERT(fence == NULL);
if (!signaled)
goto out;
}
+
+ /* If anything changed while we were testing, restart. */
+ if (!dma_resv_read_valid(robj, &ticket))
+ goto restart;
}
/* If there is an exclusive fence, test it. */
@@ -1114,6 +1126,10 @@ top: KASSERT(fence == NULL);
dma_fence_put(fence);
fence = NULL;
}
+
+ /* If anything changed while we were testing, restart. */
+ if (!dma_resv_read_valid(robj, &ticket))
+ goto restart;
}
/* If there is an exclusive fence, test it. */
