[PATCH 4.8 29/96] drm/nouveau/fifo/gf100-: protect channel preempt with subdev mutex

From: Greg Kroah-Hartman
Date: Fri Jan 06 2017 - 16:50:16 EST


4.8-stable review patch. If anyone has any objections, please let me know.

------------------

From: Ben Skeggs <bskeggs@xxxxxxxxxx>

commit b27add13f500469127afdf011dbcc9c649e16e54 upstream.

This avoids an issue that occurs when we're attempting to preempt multiple
channels simultaneously. HW seems to ignore preempt requests while it's
still processing a previous one, which, well, makes sense.

Fixes random "fifo: SCHED_ERROR 0d []" + GPCCS page faults during parallel
piglit runs on (at least) GM107.

Signed-off-by: Ben Skeggs <bskeggs@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
drivers/gpu/drm/nouveau/nvkm/engine/fifo/gpfifogf100.c | 9 ++++++---
drivers/gpu/drm/nouveau/nvkm/engine/fifo/gpfifogk104.c | 8 +++++---
2 files changed, 11 insertions(+), 6 deletions(-)

--- a/drivers/gpu/drm/nouveau/nvkm/engine/fifo/gpfifogf100.c
+++ b/drivers/gpu/drm/nouveau/nvkm/engine/fifo/gpfifogf100.c
@@ -60,6 +60,7 @@ gf100_fifo_gpfifo_engine_fini(struct nvk
struct nvkm_gpuobj *inst = chan->base.inst;
int ret = 0;

+ mutex_lock(&subdev->mutex);
nvkm_wr32(device, 0x002634, chan->base.chid);
if (nvkm_msec(device, 2000,
if (nvkm_rd32(device, 0x002634) == chan->base.chid)
@@ -67,10 +68,12 @@ gf100_fifo_gpfifo_engine_fini(struct nvk
) < 0) {
nvkm_error(subdev, "channel %d [%s] kick timeout\n",
chan->base.chid, chan->base.object.client->name);
- ret = -EBUSY;
- if (suspend)
- return ret;
+ ret = -ETIMEDOUT;
}
+ mutex_unlock(&subdev->mutex);
+
+ if (ret && suspend)
+ return ret;

if (offset) {
nvkm_kmap(inst);
--- a/drivers/gpu/drm/nouveau/nvkm/engine/fifo/gpfifogk104.c
+++ b/drivers/gpu/drm/nouveau/nvkm/engine/fifo/gpfifogk104.c
@@ -40,7 +40,9 @@ gk104_fifo_gpfifo_kick(struct gk104_fifo
struct nvkm_subdev *subdev = &fifo->base.engine.subdev;
struct nvkm_device *device = subdev->device;
struct nvkm_client *client = chan->base.object.client;
+ int ret = 0;

+ mutex_lock(&subdev->mutex);
nvkm_wr32(device, 0x002634, chan->base.chid);
if (nvkm_msec(device, 2000,
if (!(nvkm_rd32(device, 0x002634) & 0x00100000))
@@ -48,10 +50,10 @@ gk104_fifo_gpfifo_kick(struct gk104_fifo
) < 0) {
nvkm_error(subdev, "channel %d [%s] kick timeout\n",
chan->base.chid, client->name);
- return -EBUSY;
+ ret = -ETIMEDOUT;
}
-
- return 0;
+ mutex_unlock(&subdev->mutex);
+ return ret;
}

static u32