[igt-dev] [PATCH i-g-t] i915/gem_pread, gem_pwrite: Exercise using ourselves as the buffer

[Chris Wilson]

If we caused a fault on a GEM buffer while in the middle of trying to
write/read into that buffer, we could conceivably deadlock (e.g.
recursing on struct_mutex if we are not careful). Exercise these cases
by supplying a fresh mmap to pread/pwrite in both non-overlapping and
overlapping copies.

Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
---
 tests/i915/gem_pread.c  | 31 +++++++++++++++++++++++++++++++
 tests/i915/gem_pwrite.c | 31 +++++++++++++++++++++++++++++++
 2 files changed, 62 insertions(+)

diff --git a/tests/i915/gem_pread.c b/tests/i915/gem_pread.c
index 00379580c..60830c5c5 100644
--- a/tests/i915/gem_pread.c
+++ b/tests/i915/gem_pread.c
@@ -39,6 +39,34 @@
 #include <sys/time.h>
 #include "drm.h"
 
+#define MiB(x) ((x) * 1024 * 1024)
+
+static void pread_self(int i915)
+{
+	uint32_t handle = gem_create(i915, MiB(4));
+	void *ptr;
+
+	ptr = gem_mmap__gtt(i915, handle, MiB(4), PROT_WRITE);
+	gem_read(i915, handle, 0, ptr + MiB(3), MiB(1));
+	gem_read(i915, handle, MiB(3), ptr, MiB(1));
+	gem_read(i915, handle, MiB(1), ptr + MiB(1), MiB(2));
+	munmap(ptr, MiB(4));
+
+	ptr = gem_mmap__cpu(i915, handle, 0, MiB(4), PROT_WRITE);
+	gem_read(i915, handle, 0, ptr + MiB(3), MiB(1));
+	gem_read(i915, handle, MiB(3), ptr, MiB(1));
+	gem_read(i915, handle, MiB(1), ptr + MiB(1), MiB(2));
+	munmap(ptr, MiB(4));
+
+	ptr = gem_mmap__wc(i915, handle, 0, MiB(4), PROT_WRITE);
+	gem_read(i915, handle, 0, ptr + MiB(3), MiB(1));
+	gem_read(i915, handle, MiB(3), ptr, MiB(1));
+	gem_read(i915, handle, MiB(1), ptr + MiB(1), MiB(2));
+	munmap(ptr, MiB(4));
+
+	gem_close(i915, handle);
+}
+
 #define OBJECT_SIZE 16384
 #define LARGE_OBJECT_SIZE 1024 * 1024
 #define KGRN "\x1B[32m"
@@ -131,6 +159,9 @@ int main(int argc, char **argv)
 		}
 	}
 
+	igt_subtest("self")
+		pread_self(fd);
+
 	for (c = cache; c->level != -1; c++) {
 		igt_subtest(c->name) {
 			gem_set_caching(fd, dst, c->level);
diff --git a/tests/i915/gem_pwrite.c b/tests/i915/gem_pwrite.c
index 696bd316a..684b4b216 100644
--- a/tests/i915/gem_pwrite.c
+++ b/tests/i915/gem_pwrite.c
@@ -39,6 +39,34 @@
 #include <sys/time.h>
 #include "drm.h"
 
+#define MiB(x) ((x) * 1024 * 1024)
+
+static void pwrite_self(int i915)
+{
+	uint32_t handle = gem_create(i915, MiB(4));
+	void *ptr;
+
+	ptr = gem_mmap__gtt(i915, handle, MiB(4), PROT_READ);
+	gem_write(i915, handle, 0, ptr + MiB(3), MiB(1));
+	gem_write(i915, handle, MiB(3), ptr, MiB(1));
+	gem_write(i915, handle, MiB(1), ptr + MiB(1), MiB(2));
+	munmap(ptr, MiB(4));
+
+	ptr = gem_mmap__cpu(i915, handle, 0, MiB(4), PROT_READ);
+	gem_write(i915, handle, 0, ptr + MiB(3), MiB(1));
+	gem_write(i915, handle, MiB(3), ptr, MiB(1));
+	gem_write(i915, handle, MiB(1), ptr + MiB(1), MiB(2));
+	munmap(ptr, MiB(4));
+
+	ptr = gem_mmap__wc(i915, handle, 0, MiB(4), PROT_READ);
+	gem_write(i915, handle, 0, ptr + MiB(3), MiB(1));
+	gem_write(i915, handle, MiB(3), ptr, MiB(1));
+	gem_write(i915, handle, MiB(1), ptr + MiB(1), MiB(2));
+	munmap(ptr, MiB(4));
+
+	gem_close(i915, handle);
+}
+
 #define OBJECT_SIZE 16384
 
 #define COPY_BLT_CMD		(2<<29|0x53<<22|0x6)
@@ -258,6 +286,9 @@ int main(int argc, char **argv)
 		}
 	}
 
+	igt_subtest("self")
+		pwrite_self(fd);
+
 	for (c = cache; c->level != -1; c++) {
 		igt_subtest(c->name) {
 			gem_set_caching(fd, dst, c->level);
-- 
2.20.1