Allow drivers to resolve a WW transaction rollback. This allows for
1) Putting a lower-priority transaction to sleep allowing another to
succeed instead both fighting using trylocks.
2) Letting the driver know whether a received -ENOMEM is the result of
competition with another WW transaction, which can be resolved using
rollback and retry or a real -ENOMEM which should be propagated back
to user-space as a failure.
Signed-off-by: Thomas Hellström <thomas.hellstrom@xxxxxxxxxxxxxxx>
---
drivers/gpu/drm/ttm/ttm_bo.c | 17 +++++++++++++++--
include/drm/ttm/ttm_bo.h | 2 ++
2 files changed, 17 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c
index bd5dae4d1624..c3ccbea2be3e 100644
--- a/drivers/gpu/drm/ttm/ttm_bo.c
+++ b/drivers/gpu/drm/ttm/ttm_bo.c
@@ -561,6 +561,10 @@ static int ttm_mem_evict_wait_busy(struct ttm_buffer_object *busy_bo,
if (!busy_bo || !ticket)
return -EBUSY;
+ /* We want to resolve contention before trying to lock again. */
+ if (ctx->propagate_edeadlk && ctx->contended_bo)
+ return -EDEADLK;
+
if (ctx->interruptible)
r = dma_resv_lock_interruptible(busy_bo->base.resv,
ticket);
@@ -575,7 +579,15 @@ static int ttm_mem_evict_wait_busy(struct ttm_buffer_object *busy_bo,
if (!r)
dma_resv_unlock(busy_bo->base.resv);
- return r == -EDEADLK ? -EBUSY : r;
+ if (r == -EDEADLK) {
+ if (ctx->propagate_edeadlk) {
+ ttm_bo_get(busy_bo);
+ ctx->contended_bo = busy_bo;
+ }
+ r = -EBUSY;
+ }
+
+ return r;
}
int ttm_mem_evict_first(struct ttm_device *bdev,
@@ -816,7 +828,7 @@ int ttm_bo_mem_space(struct ttm_buffer_object *bo,
goto error;
}
- ret = -ENOMEM;
+ ret = (ctx->propagate_edeadlk && ctx->contended_bo) ? -EDEADLK : -ENOMEM;
if (!type_found) {
pr_err(TTM_PFX "No compatible memory type found\n");
ret = -EINVAL;
@@ -913,6 +925,7 @@ int ttm_bo_validate(struct ttm_buffer_object *bo,
if (ret)
return ret;
}
+
return 0;
}
EXPORT_SYMBOL(ttm_bo_validate);
diff --git a/include/drm/ttm/ttm_bo.h b/include/drm/ttm/ttm_bo.h
index 8b113c384236..d8e35a794ce5 100644
--- a/include/drm/ttm/ttm_bo.h
+++ b/include/drm/ttm/ttm_bo.h
@@ -181,8 +181,10 @@ struct ttm_operation_ctx {
bool gfp_retry_mayfail;
bool allow_res_evict;
bool force_alloc;
+ bool propagate_edeadlk;
struct dma_resv *resv;
uint64_t bytes_moved;
+ struct ttm_buffer_object *contended_bo;
};
/**
--
2.39.2
