From 54895010a893cdbf0aaf34fbd7719d750b557eb2 Mon Sep 17 00:00:00 2001
From: Chris Wilson <chris@chris-wilson.co.uk>
Date: Fri, 11 Oct 2019 18:38:23 +0100
Subject: drm/i915: Add an rcu_barrier option to i915_drop_caches
Git-commit: 54895010a893cdbf0aaf34fbd7719d750b557eb2
Patch-mainline: v5.5-rc1
References: bsc#1152489
Sometimes a test has to wait for RCU to complete a grace period and
perform its callbacks, for example waiting for a close(fd) to actually
perform the fput(filp) and so trigger all the callbacks such as closing
GEM contexts. There is no trivial means of triggering an RCU barrier
from userspace, so add one for our convenience in
debugfs/i915_drop_caches
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Matthew Auld <matthew.william.auld@gmail.com>
Reviewed-by: Matthew Auld <matthew.william.auld@gmail.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191011173823.20432-1-chris@chris-wilson.co.uk
Acked-by: Thomas Zimmermann <tzimmermann@suse.de>
---
drivers/gpu/drm/i915/i915_debugfs.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
index 277f31297f29..e575761550ac 100644
--- a/drivers/gpu/drm/i915/i915_debugfs.c
+++ b/drivers/gpu/drm/i915/i915_debugfs.c
@@ -3599,6 +3599,7 @@ DEFINE_SIMPLE_ATTRIBUTE(i915_wedged_fops,
#define DROP_IDLE BIT(6)
#define DROP_RESET_ACTIVE BIT(7)
#define DROP_RESET_SEQNO BIT(8)
+#define DROP_RCU BIT(9)
#define DROP_ALL (DROP_UNBOUND | \
DROP_BOUND | \
DROP_RETIRE | \
@@ -3607,7 +3608,8 @@ DEFINE_SIMPLE_ATTRIBUTE(i915_wedged_fops,
DROP_SHRINK_ALL |\
DROP_IDLE | \
DROP_RESET_ACTIVE | \
- DROP_RESET_SEQNO)
+ DROP_RESET_SEQNO | \
+ DROP_RCU)
static int
i915_drop_caches_get(void *data, u64 *val)
{
@@ -3659,6 +3661,9 @@ i915_drop_caches_set(void *data, u64 val)
i915_gem_shrink_all(i915);
fs_reclaim_release(GFP_KERNEL);
+ if (val & DROP_RCU)
+ rcu_barrier();
+
if (val & DROP_FREED)
i915_gem_drain_freed_objects(i915);
--
2.28.0