drm/i915/eb: Drop unmotivated cond_resched

This was added in

commit 2889caa9232109afc8881f29a2205abeb5709d0c
Author: Chris Wilson <chris@chris-wilson.co.uk>
Date:   Fri Jun 16 15:05:19 2017 +0100

    drm/i915: Eliminate lots of iterations over the execobjects array

without any motivation.

I suspect it was added to handle EAGAIN errors from userptr, but it's
hard to guess with no breadcrumbs anywhere. Before this change there
wasn't any dedicated EAGAIN handling, we just bounced completely to
userspace.

Userptr works differently now and does not just thrash the cpu until
another worker has maybe acquired the pages, so we can go back to
handling EAGAIN like beforehand.

That also allows us to drop another funky repeat loop from a function
with already very complicated control flow (which unforunately got
more complex due to ww_mutex restarting).

Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Cc: Jon Bloomfield <jon.bloomfield@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: "Thomas Hellström" <thomas.hellstrom@linux.intel.com>
Cc: Matthew Auld <matthew.auld@intel.com>
Cc: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Cc: Dave Airlie <airlied@redhat.com>
Cc: Jason Ekstrand <jason@jlekstrand.net>

1 files changed, 1 insertions, 10 deletions

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
index 9f8c32c93d82..dc2daf780ffd 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
@@ -1795,7 +1795,7 @@ repeat:
 	i915_gem_ww_ctx_fini(&eb->ww);
 
 	/*
-	 * We take 3 passes through the slowpatch.
+	 * We take 2 passes through the slowpatch.
 	 *
 	 * 1 - we try to just prefault all the user relocation entries and
 	 * then attempt to reuse the atomic pagefault disabled fast path again.
@@ -1803,18 +1803,12 @@ repeat:
 	 * 2 - we copy the user entries to a local buffer here outside of the
 	 * local and allow ourselves to wait upon any rendering before
 	 * relocations
-	 *
-	 * 3 - we already have a local copy of the relocation entries, but
-	 * were interrupted (EAGAIN) whilst waiting for the objects, try again.
 	 */
 	if (!err) {
 		err = eb_prefault_relocations(eb);
 	} else if (!have_copy) {
 		err = eb_copy_relocations(eb);
 		have_copy = err == 0;
-	} else {
-		cond_resched();
-		err = 0;
 	}
 
 	if (!err)
@@ -1877,9 +1871,6 @@ err:
 			goto repeat_validate;
 	}
 
-	if (err == -EAGAIN)
-		goto repeat;
-
 out:
 	if (have_copy) {
 		const unsigned int count = eb->buffer_count;