[PATCH v2 7/7] drm/msm/gem: Convert to drm_exec

Rob Clark
2023-11-21T00:41:07Z

Replace the ww_mutex locking dance with the drm_exec helper.

v2: Error path fixes, move drm_exec_fini so we only call it once (and
only if we have drm_exec_init()

Signed-off-by: Rob Clark <robdclark@chromium.org>
---
drivers/gpu/drm/msm/Kconfig | 1 +
drivers/gpu/drm/msm/msm_gem.h | 5 +-
drivers/gpu/drm/msm/msm_gem_submit.c | 119 +++++----------------------
3 files changed, 24 insertions(+), 101 deletions(-)

diff --git a/drivers/gpu/drm/msm/Kconfig b/drivers/gpu/drm/msm/Kconfig
index 6309a857ca31..f91d87afc0d3 100644
--- a/drivers/gpu/drm/msm/Kconfig
+++ b/drivers/gpu/drm/msm/Kconfig
@@ -16,6 +16,7 @@ config DRM_MSM
select DRM_DP_AUX_BUS
select DRM_DISPLAY_DP_HELPER
select DRM_DISPLAY_HELPER
+ select DRM_EXEC
select DRM_KMS_HELPER
select DRM_PANEL
select DRM_BRIDGE
diff --git a/drivers/gpu/drm/msm/msm_gem.h b/drivers/gpu/drm/msm/msm_gem.h
index af884ced7a0d..7f34263048a3 100644
--- a/drivers/gpu/drm/msm/msm_gem.h
+++ b/drivers/gpu/drm/msm/msm_gem.h
@@ -9,6 +9,7 @@

#include <linux/kref.h>
#include <linux/dma-resv.h>
+#include "drm/drm_exec.h"
#include "drm/gpu_scheduler.h"
#include "msm_drv.h"

@@ -254,7 +255,7 @@ struct msm_gem_submit {
struct msm_gpu *gpu;
struct msm_gem_address_space *aspace;
struct list_head node; /* node in ring submit list */
- struct ww_acquire_ctx ticket;
+ struct drm_exec exec;
uint32_t seqno; /* Sequence number of the submit on the ring */

/* Hw fence, which is created when the scheduler executes the job, and
@@ -287,8 +288,6 @@ struct msm_gem_submit {
struct drm_msm_gem_submit_reloc *relocs;
} *cmd; /* array of size nr_cmds */
struct {
-/* make sure these don't conflict w/ MSM_SUBMIT_BO_x */
-#define BO_LOCKED 0x4000 /* obj lock is held */
uint32_t flags;
union {
struct drm_gem_object *obj;
diff --git a/drivers/gpu/drm/msm/msm_gem_submit.c b/drivers/gpu/drm/msm/msm_gem_submit.c
index 603f04d851d9..40878c26a749 100644
--- a/drivers/gpu/drm/msm/msm_gem_submit.c
+++ b/drivers/gpu/drm/msm/msm_gem_submit.c
@@ -248,85 +248,30 @@ static int submit_lookup_cmds(struct msm_gem_submit *submit,
return ret;
}

-static void submit_unlock_bo(struct msm_gem_submit *submit, int i)
-{
- struct drm_gem_object *obj = submit->bos[i].obj;
- unsigned cleanup_flags = BO_LOCKED;
- unsigned flags = submit->bos[i].flags & cleanup_flags;
-
- /*
- * Clear flags bit before dropping lock, so that the msm_job_run()
- * path isn't racing with submit_cleanup() (ie. the read/modify/
- * write is protected by the obj lock in all paths)
- */
- submit->bos[i].flags &= ~cleanup_flags;
-
- if (flags & BO_LOCKED)
- dma_resv_unlock(obj->resv);
-}
-
/* This is where we make sure all the bo's are reserved and pin'd: */
static int submit_lock_objects(struct msm_gem_submit *submit)
{
- int contended, slow_locked = -1, i, ret = 0;
-
-retry:
- for (i = 0; i < submit->nr_bos; i++) {
- struct drm_gem_object *obj = submit->bos[i].obj;
-
- if (slow_locked == i)
- slow_locked = -1;
+ int ret;

- contended = i;
+ drm_exec_init(&submit->exec, DRM_EXEC_INTERRUPTIBLE_WAIT, submit->nr_bos);

- if (!(submit->bos[i].flags & BO_LOCKED)) {
- ret = dma_resv_lock_interruptible(obj->resv,
- &submit->ticket);
+ drm_exec_until_all_locked (&submit->exec) {
+ for (unsigned i = 0; i < submit->nr_bos; i++) {
+ struct drm_gem_object *obj = submit->bos[i].obj;
+ ret = drm_exec_prepare_obj(&submit->exec, obj, 1);
+ drm_exec_retry_on_contention(&submit->exec);
if (ret)
- goto fail;
- submit->bos[i].flags |= BO_LOCKED;
+ goto error;
}
}

- ww_acquire_done(&submit->ticket);
-
return 0;

-fail:
- if (ret == -EALREADY) {
- SUBMIT_ERROR(submit, "handle %u at index %u already on submit list\n",
- submit->bos[i].handle, i);
- ret = -EINVAL;
- }
-
- for (; i >= 0; i--)
- submit_unlock_bo(submit, i);
-
- if (slow_locked > 0)
- submit_unlock_bo(submit, slow_locked);
-
- if (ret == -EDEADLK) {
- struct drm_gem_object *obj = submit->bos[contended].obj;
- /* we lost out in a seqno race, lock and retry.. */
- ret = dma_resv_lock_slow_interruptible(obj->resv,
- &submit->ticket);
- if (!ret) {
- submit->bos[contended].flags |= BO_LOCKED;
- slow_locked = contended;
- goto retry;
- }
-
- /* Not expecting -EALREADY here, if the bo was already
- * locked, we should have gotten -EALREADY already from
- * the dma_resv_lock_interruptable() call.
- */
- WARN_ON_ONCE(ret == -EALREADY);
- }
-
+error:
return ret;
}

-static int submit_fence_sync(struct msm_gem_submit *submit, bool no_implicit)
+static int submit_fence_sync(struct msm_gem_submit *submit)
{
int i, ret = 0;

@@ -334,22 +279,6 @@ static int submit_fence_sync(struct msm_gem_submit *submit, bool no_implicit)
struct drm_gem_object *obj = submit->bos[i].obj;
bool write = submit->bos[i].flags & MSM_SUBMIT_BO_WRITE;

- /* NOTE: _reserve_shared() must happen before
- * _add_shared_fence(), which makes this a slightly
- * strange place to call it. OTOH this is a
- * convenient can-fail point to hook it in.
- */
- ret = dma_resv_reserve_fences(obj->resv, 1);
- if (ret)
- return ret;
-
- /* If userspace has determined that explicit fencing is
- * used, it can disable implicit sync on the entire
- * submit:
- */
- if (no_implicit)
- continue;
-
/* Otherwise userspace can ask for implicit sync to be
* disabled on specific buffers. This is useful for internal
* usermode driver managed buffers, suballocation, etc.
@@ -529,17 +458,14 @@ static int submit_reloc(struct msm_gem_submit *submit, struct drm_gem_object *ob
*/
static void submit_cleanup(struct msm_gem_submit *submit, bool error)
{
- unsigned i;
-
- if (error)
+ if (error) {
submit_unpin_objects(submit);
-
- for (i = 0; i < submit->nr_bos; i++) {
- struct drm_gem_object *obj = submit->bos[i].obj;
- submit_unlock_bo(submit, i);
- if (error)
- drm_gem_object_put(obj);
+ /* job wasn't enqueued to scheduler, so early retirement: */
+ msm_submit_retire(submit);
}
+
+ if (submit->exec.objects)
+ drm_exec_fini(&submit->exec);
}

void msm_submit_retire(struct msm_gem_submit *submit)
@@ -733,7 +659,6 @@ int msm_ioctl_gem_submit(struct drm_device *dev, void *data,
struct msm_submit_post_dep *post_deps = NULL;
struct drm_syncobj **syncobjs_to_reset = NULL;
int out_fence_fd = -1;
- bool has_ww_ticket = false;
unsigned i;
int ret;

@@ -839,15 +764,15 @@ int msm_ioctl_gem_submit(struct drm_device *dev, void *data,
goto out;

/* copy_*_user while holding a ww ticket upsets lockdep */
- ww_acquire_init(&submit->ticket, &reservation_ww_class);
- has_ww_ticket = true;
ret = submit_lock_objects(submit);
if (ret)
goto out;

- ret = submit_fence_sync(submit, !!(args->flags & MSM_SUBMIT_NO_IMPLICIT));
- if (ret)
- goto out;
+ if (!(args->flags & MSM_SUBMIT_NO_IMPLICIT)) {
+ ret = submit_fence_sync(submit);
+ if (ret)
+ goto out;
+ }

ret = submit_pin_objects(submit);
if (ret)
@@ -978,8 +903,6 @@ int msm_ioctl_gem_submit(struct drm_device *dev, void *data,

out:
submit_cleanup(submit, !!ret);
- if (has_ww_ticket)
- ww_acquire_fini(&submit->ticket);
out_unlock:
mutex_unlock(&queue->lock);
out_post_unlock:
--
2.42.0