+       /* did fence get signaled after we enabled the sw irq? */
+       if (atomic64_read(&fence->rdev->fence_drv[fence->ring].last_seq) >= 
fence->seq) {
+               radeon_irq_kms_sw_irq_put(fence->rdev, fence->ring);
+               return false;
+       }
+
+       fence->fence_wake.flags = 0;
+       fence->fence_wake.private = NULL;
+       fence->fence_wake.func = radeon_fence_check_signaled;
+       __add_wait_queue(&fence->rdev->fence_queue, &fence->fence_wake);
+       fence_get(f);
That looks like a race condition to me. The fence needs to be added to the wait queue before the check, not after.

Apart from that the whole approach looks like a really bad idea to me. How for example is lockup detection supposed to happen with this?

Christian.

Am 14.05.2014 16:58, schrieb Maarten Lankhorst:
Signed-off-by: Maarten Lankhorst <maarten.lankho...@canonical.com>
---
  drivers/gpu/drm/radeon/radeon.h        |   15 +--
  drivers/gpu/drm/radeon/radeon_device.c |    1
  drivers/gpu/drm/radeon/radeon_fence.c  |  189 +++++++++++++++++++++++++-------
  3 files changed, 153 insertions(+), 52 deletions(-)

diff --git a/drivers/gpu/drm/radeon/radeon.h b/drivers/gpu/drm/radeon/radeon.h
index 68528619834a..a7d839a158ae 100644
--- a/drivers/gpu/drm/radeon/radeon.h
+++ b/drivers/gpu/drm/radeon/radeon.h
@@ -64,6 +64,7 @@
  #include <linux/wait.h>
  #include <linux/list.h>
  #include <linux/kref.h>
+#include <linux/fence.h>
#include <ttm/ttm_bo_api.h>
  #include <ttm/ttm_bo_driver.h>
@@ -113,9 +114,6 @@ extern int radeon_hard_reset;
  #define RADEONFB_CONN_LIMIT                   4
  #define RADEON_BIOS_NUM_SCRATCH                       8
-/* fence seq are set to this number when signaled */
-#define RADEON_FENCE_SIGNALED_SEQ              0LL
-
  /* internal ring indices */
  /* r1xx+ has gfx CP ring */
  #define RADEON_RING_TYPE_GFX_INDEX            0
@@ -347,12 +345,15 @@ struct radeon_fence_driver {
  };
struct radeon_fence {
+       struct fence base;
+
        struct radeon_device            *rdev;
-       struct kref                     kref;
        /* protected by radeon_fence.lock */
        uint64_t                        seq;
        /* RB, DMA, etc. */
        unsigned                        ring;
+
+       wait_queue_t fence_wake;
  };
int radeon_fence_driver_start_ring(struct radeon_device *rdev, int ring);
@@ -2256,6 +2257,7 @@ struct radeon_device {
        struct radeon_mman              mman;
        struct radeon_fence_driver      fence_drv[RADEON_NUM_RINGS];
        wait_queue_head_t               fence_queue;
+       unsigned                        fence_context;
        struct mutex                    ring_lock;
        struct radeon_ring              ring[RADEON_NUM_RINGS];
        bool                            ib_pool_ready;
@@ -2346,11 +2348,6 @@ u32 cik_mm_rdoorbell(struct radeon_device *rdev, u32 
index);
  void cik_mm_wdoorbell(struct radeon_device *rdev, u32 index, u32 v);
/*
- * Cast helper
- */
-#define to_radeon_fence(p) ((struct radeon_fence *)(p))
-
-/*
   * Registers read & write functions.
   */
  #define RREG8(reg) readb((rdev->rmmio) + (reg))
diff --git a/drivers/gpu/drm/radeon/radeon_device.c 
b/drivers/gpu/drm/radeon/radeon_device.c
index 0e770bbf7e29..501d0cf9eb8b 100644
--- a/drivers/gpu/drm/radeon/radeon_device.c
+++ b/drivers/gpu/drm/radeon/radeon_device.c
@@ -1175,6 +1175,7 @@ int radeon_device_init(struct radeon_device *rdev,
        for (i = 0; i < RADEON_NUM_RINGS; i++) {
                rdev->ring[i].idx = i;
        }
+       rdev->fence_context = fence_context_alloc(RADEON_NUM_RINGS);
DRM_INFO("initializing kernel modesetting (%s 0x%04X:0x%04X 0x%04X:0x%04X).\n",
                radeon_family_name[rdev->family], pdev->vendor, pdev->device,
diff --git a/drivers/gpu/drm/radeon/radeon_fence.c 
b/drivers/gpu/drm/radeon/radeon_fence.c
index a77b1c13ea43..bc844f300d3f 100644
--- a/drivers/gpu/drm/radeon/radeon_fence.c
+++ b/drivers/gpu/drm/radeon/radeon_fence.c
@@ -39,6 +39,15 @@
  #include "radeon.h"
  #include "radeon_trace.h"
+static const struct fence_ops radeon_fence_ops;
+
+#define to_radeon_fence(p) \
+       ({                                                              \
+               struct radeon_fence *__f;                               \
+               __f = container_of((p), struct radeon_fence, base);     \
+               __f->base.ops == &radeon_fence_ops ? __f : NULL; \
+       })
+
  /*
   * Fences
   * Fences mark an event in the GPUs pipeline and are used
@@ -111,30 +120,55 @@ int radeon_fence_emit(struct radeon_device *rdev,
                      struct radeon_fence **fence,
                      int ring)
  {
+       u64 seq = ++rdev->fence_drv[ring].sync_seq[ring];
+
        /* we are protected by the ring emission mutex */
        *fence = kmalloc(sizeof(struct radeon_fence), GFP_KERNEL);
        if ((*fence) == NULL) {
                return -ENOMEM;
        }
-       kref_init(&((*fence)->kref));
-       (*fence)->rdev = rdev;
-       (*fence)->seq = ++rdev->fence_drv[ring].sync_seq[ring];
        (*fence)->ring = ring;
+       __fence_init(&(*fence)->base, &radeon_fence_ops,
+                    &rdev->fence_queue.lock, rdev->fence_context + ring, seq);
+       (*fence)->rdev = rdev;
+       (*fence)->seq = seq;
        radeon_fence_ring_emit(rdev, ring, *fence);
        trace_radeon_fence_emit(rdev->ddev, ring, (*fence)->seq);
        return 0;
  }
/**
- * radeon_fence_process - process a fence
+ * radeon_fence_check_signaled - callback from fence_queue
   *
- * @rdev: radeon_device pointer
- * @ring: ring index the fence is associated with
- *
- * Checks the current fence value and wakes the fence queue
- * if the sequence number has increased (all asics).
+ * this function is called with fence_queue lock held, which is also used
+ * for the fence locking itself, so unlocked variants are used for
+ * fence_signal, and remove_wait_queue.
   */
-void radeon_fence_process(struct radeon_device *rdev, int ring)
+static int radeon_fence_check_signaled(wait_queue_t *wait, unsigned mode, int 
flags, void *key)
+{
+       struct radeon_fence *fence;
+       u64 seq;
+
+       fence = container_of(wait, struct radeon_fence, fence_wake);
+
+       seq = atomic64_read(&fence->rdev->fence_drv[fence->ring].last_seq);
+       if (seq >= fence->seq) {
+               int ret = __fence_signal(&fence->base);
+
+               if (!ret)
+                       FENCE_TRACE(&fence->base, "signaled from irq 
context\n");
+               else
+                       FENCE_TRACE(&fence->base, "was already signaled\n");
+
+               radeon_irq_kms_sw_irq_put(fence->rdev, fence->ring);
+               __remove_wait_queue(&fence->rdev->fence_queue, 
&fence->fence_wake);
+               fence_put(&fence->base);
+       } else
+               FENCE_TRACE(&fence->base, "pending\n");
+       return 0;
+}
+
+static bool __radeon_fence_process(struct radeon_device *rdev, int ring)
  {
        uint64_t seq, last_seq, last_emitted;
        unsigned count_loop = 0;
@@ -190,23 +224,22 @@ void radeon_fence_process(struct radeon_device *rdev, int 
ring)
                }
        } while (atomic64_xchg(&rdev->fence_drv[ring].last_seq, seq) > seq);
- if (wake)
-               wake_up_all(&rdev->fence_queue);
+       return wake;
  }
/**
- * radeon_fence_destroy - destroy a fence
+ * radeon_fence_process - process a fence
   *
- * @kref: fence kref
+ * @rdev: radeon_device pointer
+ * @ring: ring index the fence is associated with
   *
- * Frees the fence object (all asics).
+ * Checks the current fence value and wakes the fence queue
+ * if the sequence number has increased (all asics).
   */
-static void radeon_fence_destroy(struct kref *kref)
+void radeon_fence_process(struct radeon_device *rdev, int ring)
  {
-       struct radeon_fence *fence;
-
-       fence = container_of(kref, struct radeon_fence, kref);
-       kfree(fence);
+       if (__radeon_fence_process(rdev, ring))
+               wake_up_all(&rdev->fence_queue);
  }
/**
@@ -237,6 +270,49 @@ static bool radeon_fence_seq_signaled(struct radeon_device 
*rdev,
        return false;
  }
+static bool __radeon_fence_signaled(struct fence *f)
+{
+       struct radeon_fence *fence = to_radeon_fence(f);
+
+       return radeon_fence_seq_signaled(fence->rdev, fence->seq, fence->ring);
+}
+
+/**
+ * radeon_fence_enable_signaling - enable signalling on fence
+ * @fence: fence
+ *
+ * This function is called with fence_queue lock held, and adds a callback
+ * to fence_queue that checks if this fence is signaled, and if so it
+ * signals the fence and removes itself.
+ */
+static bool radeon_fence_enable_signaling(struct fence *f)
+{
+       struct radeon_fence *fence = to_radeon_fence(f);
+
+       if (atomic64_read(&fence->rdev->fence_drv[fence->ring].last_seq) >= 
fence->seq ||
+           !fence->rdev->ddev->irq_enabled)
+               return false;
+
+       radeon_irq_kms_sw_irq_get(fence->rdev, fence->ring);
+
+       if (__radeon_fence_process(fence->rdev, fence->ring))
+               wake_up_all_locked(&fence->rdev->fence_queue);
+
+       /* did fence get signaled after we enabled the sw irq? */
+       if (atomic64_read(&fence->rdev->fence_drv[fence->ring].last_seq) >= 
fence->seq) {
+               radeon_irq_kms_sw_irq_put(fence->rdev, fence->ring);
+               return false;
+       }
+
+       fence->fence_wake.flags = 0;
+       fence->fence_wake.private = NULL;
+       fence->fence_wake.func = radeon_fence_check_signaled;
+       __add_wait_queue(&fence->rdev->fence_queue, &fence->fence_wake);
+       fence_get(f);
+
+       return true;
+}
+
  /**
   * radeon_fence_signaled - check if a fence has signaled
   *
@@ -250,11 +326,13 @@ bool radeon_fence_signaled(struct radeon_fence *fence)
        if (!fence) {
                return true;
        }
-       if (fence->seq == RADEON_FENCE_SIGNALED_SEQ) {
-               return true;
-       }
+
        if (radeon_fence_seq_signaled(fence->rdev, fence->seq, fence->ring)) {
-               fence->seq = RADEON_FENCE_SIGNALED_SEQ;
+               int ret;
+
+               ret = fence_signal(&fence->base);
+               if (!ret)
+                       FENCE_TRACE(&fence->base, "signaled from 
radeon_fence_signaled\n");
                return true;
        }
        return false;
@@ -386,7 +464,7 @@ static int radeon_fence_wait_seq(struct radeon_device 
*rdev, u64 *target_seq,
   * radeon_fence_wait - wait for a fence to signal
   *
   * @fence: radeon fence object
- * @intr: use interruptable sleep
+ * @intr: use interruptible sleep
   *
   * Wait for the requested fence to signal (all asics).
   * @intr selects whether to use interruptable (true) or non-interruptable
@@ -398,20 +476,17 @@ int radeon_fence_wait(struct radeon_fence *fence, bool 
intr)
        uint64_t seq[RADEON_NUM_RINGS] = {};
        int r;
- if (fence == NULL) {
-               WARN(1, "Querying an invalid fence : %p !\n", fence);
-               return -EINVAL;
-       }
-
-       seq[fence->ring] = fence->seq;
-       if (seq[fence->ring] == RADEON_FENCE_SIGNALED_SEQ)
+       if (test_bit(FENCE_FLAG_SIGNALED_BIT, &fence->base.flags))
                return 0;
+ seq[fence->ring] = fence->seq;
        r = radeon_fence_wait_seq(fence->rdev, seq, intr);
-       if (r)
+       if (r) {
                return r;
-
-       fence->seq = RADEON_FENCE_SIGNALED_SEQ;
+       }
+       r = fence_signal(&fence->base);
+       if (!r)
+               FENCE_TRACE(&fence->base, "signaled from fence_wait\n");
        return 0;
  }
@@ -443,12 +518,13 @@ int radeon_fence_wait_any(struct radeon_device *rdev,
                        continue;
                }
+ if (test_bit(FENCE_FLAG_SIGNALED_BIT, &fences[i]->base.flags)) {
+                       /* already signaled */
+                       return 0;
+               }
+
                seq[i] = fences[i]->seq;
                ++num_rings;
-
-               /* test if something was allready signaled */
-               if (seq[i] == RADEON_FENCE_SIGNALED_SEQ)
-                       return 0;
        }
/* nothing to wait for ? */
@@ -525,7 +601,7 @@ int radeon_fence_wait_empty(struct radeon_device *rdev, int 
ring)
   */
  struct radeon_fence *radeon_fence_ref(struct radeon_fence *fence)
  {
-       kref_get(&fence->kref);
+       fence_get(&fence->base);
        return fence;
  }
@@ -541,9 +617,8 @@ void radeon_fence_unref(struct radeon_fence **fence)
        struct radeon_fence *tmp = *fence;
*fence = NULL;
-       if (tmp) {
-               kref_put(&tmp->kref, radeon_fence_destroy);
-       }
+       if (tmp)
+               fence_put(&tmp->base);
  }
/**
@@ -832,3 +907,31 @@ int radeon_debugfs_fence_init(struct radeon_device *rdev)
        return 0;
  #endif
  }
+
+static const char *radeon_fence_get_driver_name(struct fence *fence)
+{
+       return "radeon";
+}
+
+static const char *radeon_fence_get_timeline_name(struct fence *f)
+{
+       struct radeon_fence *fence = to_radeon_fence(f);
+       switch (fence->ring) {
+       case RADEON_RING_TYPE_GFX_INDEX: return "radeon.gfx";
+       case CAYMAN_RING_TYPE_CP1_INDEX: return "radeon.cp1";
+       case CAYMAN_RING_TYPE_CP2_INDEX: return "radeon.cp2";
+       case R600_RING_TYPE_DMA_INDEX: return "radeon.dma";
+       case CAYMAN_RING_TYPE_DMA1_INDEX: return "radeon.dma1";
+       case R600_RING_TYPE_UVD_INDEX: return "radeon.uvd";
+       default: WARN_ON_ONCE(1); return "radeon.unk";
+       }
+}
+
+static const struct fence_ops radeon_fence_ops = {
+       .get_driver_name = radeon_fence_get_driver_name,
+       .get_timeline_name = radeon_fence_get_timeline_name,
+       .enable_signaling = radeon_fence_enable_signaling,
+       .signaled = __radeon_fence_signaled,
+       .wait = fence_default_wait,
+       .release = NULL,
+};

_______________________________________________
dri-devel mailing list
dri-de...@lists.freedesktop.org
http://lists.freedesktop.org/mailman/listinfo/dri-devel

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

Reply via email to