From a76cf56920966a384b578f7b099bd1f073cc2a92 Mon Sep 17 00:00:00 2001
From: Chris Wilson <chris@chris-wilson.co.uk>
Date: Tue, 17 Dec 2019 13:47:29 +0000
Subject: drm/i915/gem: Keep request alive while attaching fences
Git-commit: a76cf56920966a384b578f7b099bd1f073cc2a92
Patch-mainline: v5.5-rc3
References: bsc#1152489
Since commit e5dadff4b093 ("drm/i915: Protect request retirement with
timeline->mutex"), the request retirement can happen outside of the
struct_mutex serialised only by the timeline->mutex. We drop the
timeline->mutex on submitting the request (i915_request_add) so after
that point, it is liable to be freed. Make sure our local reference is
kept alive until we have finished attaching it to the signalers. (Note
that this erodes the argument that i915_request_add should consume the
reference, but that is a slightly larger patch!)
Fixes: e5dadff4b093 ("drm/i915: Protect request retirement with timeline->mutex")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Matthew Auld <matthew.auld@intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191217134729.3297818-1-chris@chris-wilson.co.uk
(cherry picked from commit e14177f19739d74839eb496a27f5f5d958beaa5b)
Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Acked-by: Thomas Zimmermann <tzimmermann@suse.de>
---
drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
index f0998f1225af..bc3a67226163 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
@@ -2694,6 +2694,7 @@ i915_gem_do_execbuffer(struct drm_device *dev,
err = eb_submit(&eb);
err_request:
add_to_client(eb.request, file);
+ i915_request_get(eb.request);
i915_request_add(eb.request);
if (fences)
@@ -2709,6 +2710,7 @@ i915_gem_do_execbuffer(struct drm_device *dev,
fput(out_fence->file);
}
}
+ i915_request_put(eb.request);
err_batch_unpin:
if (eb.batch_flags & I915_DISPATCH_SECURE)
--
2.28.0