[Intel-gfx] [PATCH 24/61] drm/i915: Take reservation lock around i915_vma_pin.

Maarten Lankhorst
2020-10-02T13:00:07Z

We previously complained when ww == NULL.

This function is now only used in selftests to pin an object,
and ww locking is now fixed.

Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
---
.../i915/gem/selftests/i915_gem_coherency.c | 14 +++++--------
drivers/gpu/drm/i915/i915_gem.c | 6 +++++-
drivers/gpu/drm/i915/i915_vma.c | 4 +---
drivers/gpu/drm/i915/i915_vma.h | 20 +++++++++++++++----
4 files changed, 27 insertions(+), 17 deletions(-)

diff --git a/drivers/gpu/drm/i915/gem/selftests/i915_gem_coherency.c b/drivers/gpu/drm/i915/gem/selftests/i915_gem_coherency.c
index 7049a6bbc03d..2e439bb269d6 100644
--- a/drivers/gpu/drm/i915/gem/selftests/i915_gem_coherency.c
+++ b/drivers/gpu/drm/i915/gem/selftests/i915_gem_coherency.c
@@ -199,16 +199,14 @@ static int gpu_set(struct context *ctx, unsigned long offset, u32 v)
u32 *cs;
int err;

+ vma = i915_gem_object_ggtt_pin(ctx->obj, NULL, 0, 0, 0);
+ if (IS_ERR(vma))
+ return PTR_ERR(vma);
+
i915_gem_object_lock(ctx->obj, NULL);
err = i915_gem_object_set_to_gtt_domain(ctx->obj, true);
if (err)
- goto out_unlock;
-
- vma = i915_gem_object_ggtt_pin(ctx->obj, NULL, 0, 0, 0);
- if (IS_ERR(vma)) {
- err = PTR_ERR(vma);
- goto out_unlock;
- }
+ goto out_unpin;

rq = intel_engine_create_kernel_request(ctx->engine);
if (IS_ERR(rq)) {
@@ -248,9 +246,7 @@ static int gpu_set(struct context *ctx, unsigned long offset, u32 v)
i915_request_add(rq);
out_unpin:
i915_vma_unpin(vma);
-out_unlock:
i915_gem_object_unlock(ctx->obj);
-
return err;
}

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index d349c0b796ec..929a8f20cca4 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -1036,7 +1036,11 @@ i915_gem_object_ggtt_pin_ww(struct drm_i915_gem_object *obj,
return ERR_PTR(ret);
}

- ret = i915_vma_pin_ww(vma, ww, size, alignment, flags | PIN_GLOBAL);
+ if (ww)
+ ret = i915_vma_pin_ww(vma, ww, size, alignment, flags | PIN_GLOBAL);
+ else
+ ret = i915_vma_pin(vma, size, alignment, flags | PIN_GLOBAL);
+
if (ret)
return ERR_PTR(ret);

diff --git a/drivers/gpu/drm/i915/i915_vma.c b/drivers/gpu/drm/i915/i915_vma.c
index f50250c8685a..ed6cf4529d5d 100644
--- a/drivers/gpu/drm/i915/i915_vma.c
+++ b/drivers/gpu/drm/i915/i915_vma.c
@@ -861,9 +861,7 @@ int i915_vma_pin_ww(struct i915_vma *vma, struct i915_gem_ww_ctx *ww,
int err;

#ifdef CONFIG_PROVE_LOCKING
- if (debug_locks && lockdep_is_held(&vma->vm->i915->drm.struct_mutex))
- WARN_ON(!ww);
- if (debug_locks && ww && vma->resv)
+ if (debug_locks && !WARN_ON(!ww) && vma->resv)
assert_vma_held(vma);
#endif

diff --git a/drivers/gpu/drm/i915/i915_vma.h b/drivers/gpu/drm/i915/i915_vma.h
index 3c951d5428cf..cea6e7b8611b 100644
--- a/drivers/gpu/drm/i915/i915_vma.h
+++ b/drivers/gpu/drm/i915/i915_vma.h
@@ -246,10 +246,22 @@ i915_vma_pin_ww(struct i915_vma *vma, struct i915_gem_ww_ctx *ww,
static inline int __must_check
i915_vma_pin(struct i915_vma *vma, u64 size, u64 alignment, u64 flags)
{
-#ifdef CONFIG_LOCKDEP
- WARN_ON_ONCE(vma->resv && dma_resv_held(vma->resv));
-#endif
- return i915_vma_pin_ww(vma, NULL, size, alignment, flags);
+ struct i915_gem_ww_ctx ww;
+ int err;
+
+ i915_gem_ww_ctx_init(&ww, true);
+retry:
+ err = i915_gem_object_lock(vma->obj, &ww);
+ if (!err)
+ err = i915_vma_pin_ww(vma, &ww, size, alignment, flags);
+ if (err == -EDEADLK) {
+ err = i915_gem_ww_ctx_backoff(&ww);
+ if (!err)
+ goto retry;
+ }
+ i915_gem_ww_ctx_fini(&ww);
+
+ return err;
}

int i915_ggtt_pin(struct i915_vma *vma, struct i915_gem_ww_ctx *ww,