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Subject[PATCH 1/2] habanalabs: Replace dma-fence mechanism with completions
Date
From: Ofir Bitton <obitton@habana.ai>

habanalabs driver uses dma-fence mechanism for synchronization.
dma-fence mechanism was designed solely for GPUs, hence we purpose
a simpler mechanism based on completions to replace current
dma-fence objects.

Signed-off-by: Ofir Bitton <obitton@habana.ai>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: Oded Gabbay <oded.gabbay@gmail.com>
Signed-off-by: Oded Gabbay <oded.gabbay@gmail.com>
---
.../habanalabs/common/command_submission.c | 93 +++++++++----------
drivers/misc/habanalabs/common/context.c | 13 +--
drivers/misc/habanalabs/common/habanalabs.h | 32 +++++--
drivers/misc/habanalabs/common/hw_queue.c | 2 +-
4 files changed, 78 insertions(+), 62 deletions(-)

diff --git a/drivers/misc/habanalabs/common/command_submission.c b/drivers/misc/habanalabs/common/command_submission.c
index b9840e368eb5..d19ac641b171 100644
--- a/drivers/misc/habanalabs/common/command_submission.c
+++ b/drivers/misc/habanalabs/common/command_submission.c
@@ -38,26 +38,10 @@ void hl_sob_reset_error(struct kref *ref)
hw_sob->q_idx, hw_sob->sob_id);
}

-static const char *hl_fence_get_driver_name(struct dma_fence *fence)
-{
- return "HabanaLabs";
-}
-
-static const char *hl_fence_get_timeline_name(struct dma_fence *fence)
-{
- struct hl_cs_compl *hl_cs_compl =
- container_of(fence, struct hl_cs_compl, base_fence);
-
- return dev_name(hl_cs_compl->hdev->dev);
-}
-
-static bool hl_fence_enable_signaling(struct dma_fence *fence)
-{
- return true;
-}
-
-static void hl_fence_release(struct dma_fence *fence)
+void hl_fence_release(struct kref *kref)
{
+ struct hl_fence *fence =
+ container_of(kref, struct hl_fence, refcount);
struct hl_cs_compl *hl_cs_cmpl =
container_of(fence, struct hl_cs_compl, base_fence);
struct hl_device *hdev = hl_cs_cmpl->hdev;
@@ -102,12 +86,24 @@ static void hl_fence_release(struct dma_fence *fence)
kfree_rcu(hl_cs_cmpl, base_fence.rcu);
}

-static const struct dma_fence_ops hl_fence_ops = {
- .get_driver_name = hl_fence_get_driver_name,
- .get_timeline_name = hl_fence_get_timeline_name,
- .enable_signaling = hl_fence_enable_signaling,
- .release = hl_fence_release
-};
+void hl_fence_put(struct hl_fence *fence)
+{
+ if (fence)
+ kref_put(&fence->refcount, hl_fence_release);
+}
+
+void hl_fence_get(struct hl_fence *fence)
+{
+ if (fence)
+ kref_get(&fence->refcount);
+}
+
+void hl_fence_init(struct hl_fence *fence)
+{
+ kref_init(&fence->refcount);
+ fence->error = 0;
+ init_completion(&fence->completion);
+}

static void cs_get(struct hl_cs *cs)
{
@@ -336,7 +332,7 @@ static void cs_do_release(struct kref *ref)
* In case the wait for signal CS was submitted, the put occurs
* in init_signal_wait_cs() right before hanging on the PQ.
*/
- dma_fence_put(cs->signal_fence);
+ hl_fence_put(cs->signal_fence);
}

/*
@@ -348,19 +344,18 @@ static void cs_do_release(struct kref *ref)
hl_ctx_put(cs->ctx);

/* We need to mark an error for not submitted because in that case
- * the dma fence release flow is different. Mainly, we don't need
+ * the hl fence release flow is different. Mainly, we don't need
* to handle hw_sob for signal/wait
*/
if (cs->timedout)
- dma_fence_set_error(cs->fence, -ETIMEDOUT);
+ cs->fence->error = -ETIMEDOUT;
else if (cs->aborted)
- dma_fence_set_error(cs->fence, -EIO);
+ cs->fence->error = -EIO;
else if (!cs->submitted)
- dma_fence_set_error(cs->fence, -EBUSY);
-
- dma_fence_signal(cs->fence);
- dma_fence_put(cs->fence);
+ cs->fence->error = -EBUSY;

+ complete_all(&cs->fence->completion);
+ hl_fence_put(cs->fence);
cs_counters_aggregate(hdev, cs->ctx);

kfree(cs->jobs_in_queue_cnt);
@@ -401,7 +396,7 @@ static int allocate_cs(struct hl_device *hdev, struct hl_ctx *ctx,
enum hl_cs_type cs_type, struct hl_cs **cs_new)
{
struct hl_cs_compl *cs_cmpl;
- struct dma_fence *other = NULL;
+ struct hl_fence *other = NULL;
struct hl_cs *cs;
int rc;

@@ -434,7 +429,8 @@ static int allocate_cs(struct hl_device *hdev, struct hl_ctx *ctx,
cs_cmpl->cs_seq = ctx->cs_sequence;
other = ctx->cs_pending[cs_cmpl->cs_seq &
(hdev->asic_prop.max_pending_cs - 1)];
- if ((other) && (!dma_fence_is_signaled(other))) {
+
+ if (other && !completion_done(&other->completion)) {
dev_dbg(hdev->dev,
"Rejecting CS because of too many in-flights CS\n");
rc = -EAGAIN;
@@ -448,8 +444,8 @@ static int allocate_cs(struct hl_device *hdev, struct hl_ctx *ctx,
goto free_fence;
}

- dma_fence_init(&cs_cmpl->base_fence, &hl_fence_ops, &cs_cmpl->lock,
- ctx->asid, ctx->cs_sequence);
+ /* init hl_fence */
+ hl_fence_init(&cs_cmpl->base_fence);

cs->sequence = cs_cmpl->cs_seq;

@@ -458,9 +454,9 @@ static int allocate_cs(struct hl_device *hdev, struct hl_ctx *ctx,
&cs_cmpl->base_fence;
ctx->cs_sequence++;

- dma_fence_get(&cs_cmpl->base_fence);
+ hl_fence_get(&cs_cmpl->base_fence);

- dma_fence_put(other);
+ hl_fence_put(other);

spin_unlock(&ctx->cs_lock);

@@ -773,7 +769,7 @@ static int cs_ioctl_signal_wait(struct hl_fpriv *hpriv, enum hl_cs_type cs_type,
struct hl_ctx *ctx = hpriv->ctx;
struct hl_cs_chunk *cs_chunk_array, *chunk;
struct hw_queue_properties *hw_queue_prop;
- struct dma_fence *sig_fence = NULL;
+ struct hl_fence *sig_fence = NULL;
struct hl_cs_job *job;
struct hl_cs *cs;
struct hl_cb *cb;
@@ -875,14 +871,14 @@ static int cs_ioctl_signal_wait(struct hl_fpriv *hpriv, enum hl_cs_type cs_type,
dev_err(hdev->dev,
"CS seq 0x%llx is not of a signal CS\n",
signal_seq);
- dma_fence_put(sig_fence);
+ hl_fence_put(sig_fence);
rc = -EINVAL;
goto free_signal_seq_array;
}

- if (dma_fence_is_signaled(sig_fence)) {
+ if (completion_done(&sig_fence->completion)) {
/* signal CS already finished */
- dma_fence_put(sig_fence);
+ hl_fence_put(sig_fence);
rc = 0;
goto free_signal_seq_array;
}
@@ -894,7 +890,7 @@ static int cs_ioctl_signal_wait(struct hl_fpriv *hpriv, enum hl_cs_type cs_type,
rc = allocate_cs(hdev, ctx, cs_type, &cs);
if (rc) {
if (cs_type == CS_TYPE_WAIT)
- dma_fence_put(sig_fence);
+ hl_fence_put(sig_fence);
hl_ctx_put(ctx);
goto free_signal_seq_array;
}
@@ -1154,7 +1150,7 @@ int hl_cs_ioctl(struct hl_fpriv *hpriv, void *data)
static long _hl_cs_wait_ioctl(struct hl_device *hdev,
struct hl_ctx *ctx, u64 timeout_us, u64 seq)
{
- struct dma_fence *fence;
+ struct hl_fence *fence;
unsigned long timeout;
long rc;

@@ -1173,12 +1169,15 @@ static long _hl_cs_wait_ioctl(struct hl_device *hdev,
"Can't wait on CS %llu because current CS is at seq %llu\n",
seq, ctx->cs_sequence);
} else if (fence) {
- rc = dma_fence_wait_timeout(fence, true, timeout);
+ rc = wait_for_completion_interruptible_timeout(
+ &fence->completion, timeout);
+
if (fence->error == -ETIMEDOUT)
rc = -ETIMEDOUT;
else if (fence->error == -EIO)
rc = -EIO;
- dma_fence_put(fence);
+
+ hl_fence_put(fence);
} else {
dev_dbg(hdev->dev,
"Can't wait on seq %llu because current CS is at seq %llu (Fence is gone)\n",
diff --git a/drivers/misc/habanalabs/common/context.c b/drivers/misc/habanalabs/common/context.c
index 3e375958e73b..b168a9fce817 100644
--- a/drivers/misc/habanalabs/common/context.c
+++ b/drivers/misc/habanalabs/common/context.c
@@ -23,7 +23,7 @@ static void hl_ctx_fini(struct hl_ctx *ctx)
*/

for (i = 0 ; i < hdev->asic_prop.max_pending_cs ; i++)
- dma_fence_put(ctx->cs_pending[i]);
+ hl_fence_put(ctx->cs_pending[i]);

kfree(ctx->cs_pending);

@@ -128,7 +128,7 @@ int hl_ctx_init(struct hl_device *hdev, struct hl_ctx *ctx, bool is_kernel_ctx)
atomic_set(&ctx->thread_ctx_switch_token, 1);
ctx->thread_ctx_switch_wait_token = 0;
ctx->cs_pending = kcalloc(hdev->asic_prop.max_pending_cs,
- sizeof(struct dma_fence *),
+ sizeof(struct hl_fence *),
GFP_KERNEL);
if (!ctx->cs_pending)
return -ENOMEM;
@@ -184,10 +184,10 @@ int hl_ctx_put(struct hl_ctx *ctx)
return kref_put(&ctx->refcount, hl_ctx_do_release);
}

-struct dma_fence *hl_ctx_get_fence(struct hl_ctx *ctx, u64 seq)
+struct hl_fence *hl_ctx_get_fence(struct hl_ctx *ctx, u64 seq)
{
struct asic_fixed_properties *asic_prop = &ctx->hdev->asic_prop;
- struct dma_fence *fence;
+ struct hl_fence *fence;

spin_lock(&ctx->cs_lock);

@@ -201,8 +201,9 @@ struct dma_fence *hl_ctx_get_fence(struct hl_ctx *ctx, u64 seq)
return NULL;
}

- fence = dma_fence_get(
- ctx->cs_pending[seq & (asic_prop->max_pending_cs - 1)]);
+ fence = ctx->cs_pending[seq & (asic_prop->max_pending_cs - 1)];
+ hl_fence_get(fence);
+
spin_unlock(&ctx->cs_lock);

return fence;
diff --git a/drivers/misc/habanalabs/common/habanalabs.h b/drivers/misc/habanalabs/common/habanalabs.h
index 018d9d67e8e6..30a399337675 100644
--- a/drivers/misc/habanalabs/common/habanalabs.h
+++ b/drivers/misc/habanalabs/common/habanalabs.h
@@ -15,7 +15,6 @@
#include <linux/cdev.h>
#include <linux/iopoll.h>
#include <linux/irqreturn.h>
-#include <linux/dma-fence.h>
#include <linux/dma-direction.h>
#include <linux/scatterlist.h>
#include <linux/hashtable.h>
@@ -342,9 +341,24 @@ struct asic_fixed_properties {
u8 completion_queues_count;
};

+/**
+ * struct hl_fence - software synchronization primitive
+ * @completion: fence is implemented using completion
+ * @refcount: refcount for this fence
+ * @rcu: used for releasing fence with kfree_rcu
+ * @error: mark this fence with error
+ *
+ */
+struct hl_fence {
+ struct completion completion;
+ struct kref refcount;
+ struct rcu_head rcu;
+ int error;
+};
+
/**
* struct hl_cs_compl - command submission completion object.
- * @base_fence: kernel fence object.
+ * @base_fence: hl fence object.
* @lock: spinlock to protect fence.
* @hdev: habanalabs device structure.
* @hw_sob: the H/W SOB used in this signal/wait CS.
@@ -353,7 +367,7 @@ struct asic_fixed_properties {
* @sob_val: the SOB value that is used in this signal/wait CS.
*/
struct hl_cs_compl {
- struct dma_fence base_fence;
+ struct hl_fence base_fence;
spinlock_t lock;
struct hl_device *hdev;
struct hl_hw_sob *hw_sob;
@@ -800,7 +814,7 @@ struct hl_va_range {
* @hdev: pointer to the device structure.
* @refcount: reference counter for the context. Context is released only when
* this hits 0l. It is incremented on CS and CS_WAIT.
- * @cs_pending: array of DMA fence objects representing pending CS.
+ * @cs_pending: array of hl fence objects representing pending CS.
* @host_va_range: holds available virtual addresses for host mappings.
* @host_huge_va_range: holds available virtual addresses for host mappings
* with huge pages.
@@ -832,7 +846,7 @@ struct hl_ctx {
struct hl_fpriv *hpriv;
struct hl_device *hdev;
struct kref refcount;
- struct dma_fence **cs_pending;
+ struct hl_fence **cs_pending;
struct hl_va_range *host_va_range;
struct hl_va_range *host_huge_va_range;
struct hl_va_range *dram_va_range;
@@ -919,8 +933,8 @@ struct hl_cs {
struct list_head job_list;
spinlock_t job_lock;
struct kref refcount;
- struct dma_fence *fence;
- struct dma_fence *signal_fence;
+ struct hl_fence *fence;
+ struct hl_fence *signal_fence;
struct work_struct finish_work;
struct delayed_work work_tdr;
struct list_head mirror_node;
@@ -1736,7 +1750,7 @@ int hl_ctx_init(struct hl_device *hdev, struct hl_ctx *ctx, bool is_kernel_ctx);
void hl_ctx_do_release(struct kref *ref);
void hl_ctx_get(struct hl_device *hdev, struct hl_ctx *ctx);
int hl_ctx_put(struct hl_ctx *ctx);
-struct dma_fence *hl_ctx_get_fence(struct hl_ctx *ctx, u64 seq);
+struct hl_fence *hl_ctx_get_fence(struct hl_ctx *ctx, u64 seq);
void hl_ctx_mgr_init(struct hl_ctx_mgr *mgr);
void hl_ctx_mgr_fini(struct hl_device *hdev, struct hl_ctx_mgr *mgr);

@@ -1778,6 +1792,8 @@ void hl_cs_rollback_all(struct hl_device *hdev);
struct hl_cs_job *hl_cs_allocate_job(struct hl_device *hdev,
enum hl_queue_type queue_type, bool is_kernel_allocated_cb);
void hl_sob_reset_error(struct kref *ref);
+void hl_fence_put(struct hl_fence *fence);
+void hl_fence_get(struct hl_fence *fence);

void goya_set_asic_funcs(struct hl_device *hdev);
void gaudi_set_asic_funcs(struct hl_device *hdev);
diff --git a/drivers/misc/habanalabs/common/hw_queue.c b/drivers/misc/habanalabs/common/hw_queue.c
index 287681646071..65b9aa69a83e 100644
--- a/drivers/misc/habanalabs/common/hw_queue.c
+++ b/drivers/misc/habanalabs/common/hw_queue.c
@@ -474,7 +474,7 @@ static void init_signal_wait_cs(struct hl_cs *cs)
* wait CS was submitted.
*/
mb();
- dma_fence_put(cs->signal_fence);
+ hl_fence_put(cs->signal_fence);
cs->signal_fence = NULL;
}
}
--
2.17.1
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