lib/ioctl_wrappers: Keep IGT working without pread/pwrite ioctls

The general direction at this time is to phase out pread/write ioctls
and not support them in future products. This means IGT must handle
the absence of these ioctls. This patch does this by modifying
gem_read() and gem_write() to do the read/write using the pread/pwrite
ioctls first but when these ioctls are unavailable fall back to doing
the read/write using a combination of mmap and memcpy.

Callers who must absolutely use the pread/pwrite ioctls (such as tests
which test these ioctls or must otherwise only use the pread/pwrite
ioctls) must use gem_require_pread_pwrite() to skip when these ioctls
are not available.

v1: Removed __gem_pread, gem_pread, __gem_pwrite and gem_pwrite
    introduced previously since they are not necessary,
    gem_require_pread_pwrite is sufficient
v2: Fix CI failures in gem_advise and gen9_exec_parse by introducing
    gem_require_pread_pwrite
v3: Skip mmap for 0 length read/write's
v4: Remove redundant igt_assert's
v5: Re-run
v6: s/EOPNOTSUPP/-EOPNOTSUPP/
v7: Rebase on latest master, skip gem_exec_parallel@userptr with
    gem_require_pread_pwrite
v8: Re-run
v9: Rebase

Acked-by: Dave Airlie <airlied@redhat.com>
Acked-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Zbigniew Kempczyński <zbigniew.kempczynski@intel.com>
Signed-off-by: Ashutosh Dixit <ashutosh.dixit@intel.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/tests/i915/gem_userptr_blits.c b/tests/i915/gem_userptr_blits.c
index 1bc2d360..7a80c016 100644
--- a/tests/i915/gem_userptr_blits.c
+++ b/tests/i915/gem_userptr_blits.c
@@ -1120,6 +1120,7 @@ static int test_forbidden_ops(int fd)
 	uint32_t handle;
 	void *ptr;
 
+	gem_require_pread_pwrite(fd);
 	igt_assert(posix_memalign(&ptr, PAGE_SIZE, PAGE_SIZE) == 0);
 	gem_userptr(fd, ptr, PAGE_SIZE, 0, userptr_flags, &handle);
 
@@ -1648,6 +1649,7 @@ static void test_readonly_pwrite(int i915)
 	 */
 
 	igt_require(igt_setup_clflush());
+	gem_require_pread_pwrite(i915);
 
 	sz = 16 << 12;
 	pages = mmap(NULL, sz, PROT_WRITE, MAP_ANON | MAP_PRIVATE, -1, 0);