[PATCH 2/2] drm/msm/gem: Add modparam to disable shrinker blocking

[Rob Clark <robin.clark@oss.qualcomm.com>]

Normally if we are under enough memory pressure, the shrinker will
eventually start waiting for BOs to become idle.  In some very latency
sensitive use-cases this is undesirable.

Signed-off-by: Rob Clark <robin.clark@oss.qualcomm.com>
---
 drivers/gpu/drm/msm/msm_gem_shrinker.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/gpu/drm/msm/msm_gem_shrinker.c b/drivers/gpu/drm/msm/msm_gem_shrinker.c
index 3514d5c84989..83ee032cb21d 100644
--- a/drivers/gpu/drm/msm/msm_gem_shrinker.c
+++ b/drivers/gpu/drm/msm/msm_gem_shrinker.c
@@ -19,6 +19,10 @@ static bool enable_eviction = true;
 MODULE_PARM_DESC(enable_eviction, "Enable swappable GEM buffers");
 module_param(enable_eviction, bool, 0600);
 
+static bool eviction_can_block = true;
+MODULE_PARM_DESC(eviction_can_block, "Enable blocking for GEM buffer to become idle for eviction");
+module_param(eviction_can_block, bool, 0600);
+
 static bool can_swap(void)
 {
 	return enable_eviction && get_nr_swap_pages() > 0;
@@ -26,6 +30,8 @@ static bool can_swap(void)
 
 static bool can_block(struct shrink_control *sc)
 {
+	if (!eviction_can_block)
+		return false;
 	return (sc->gfp_mask & __GFP_DIRECT_RECLAIM) ||
 	       (current_is_kswapd() && (sc->gfp_mask & __GFP_KSWAPD_RECLAIM));
 }
-- 
2.55.0