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Subject[PATCH 3/9] habanalabs: create context in lazy mode
Date
Instead of creating the context when the user opens the device, create the
context when the first IOCTL that needs a context is called.

This change is required to provide backward compatibility for older
user-space when the driver will require the user to create a context.

Signed-off-by: Oded Gabbay <oded.gabbay@gmail.com>
---
drivers/misc/habanalabs/context.c | 29 +++++++++++++++++++++++-
drivers/misc/habanalabs/device.c | 5 +++-
drivers/misc/habanalabs/habanalabs.h | 2 ++
drivers/misc/habanalabs/habanalabs_drv.c | 13 -----------
4 files changed, 34 insertions(+), 15 deletions(-)

diff --git a/drivers/misc/habanalabs/context.c b/drivers/misc/habanalabs/context.c
index 771a1055e67b..3c1f7c29e908 100644
--- a/drivers/misc/habanalabs/context.c
+++ b/drivers/misc/habanalabs/context.c
@@ -198,7 +198,34 @@ struct dma_fence *hl_ctx_get_fence(struct hl_ctx *ctx, u64 seq)

bool hl_ctx_is_valid(struct hl_fpriv *hpriv)
{
- return hpriv->ctx ? true : false;
+ struct hl_device *hdev = hpriv->hdev;
+ bool valid = true;
+ int rc;
+
+ /* First thing, to minimize latency impact, check if context exists.
+ * If so, exit immediately
+ */
+ if (hpriv->ctx)
+ return true;
+
+ mutex_lock(&hdev->lazy_ctx_creation_lock);
+
+ /* We must check again the existence of the context. This is because
+ * there could be competing threads in the same process that call
+ * IOCTLs at the same time. In this case, we must protect against double
+ * creation of a context
+ */
+ if (!hpriv->ctx) {
+ rc = hl_ctx_create(hdev, hpriv);
+ if (rc) {
+ dev_err(hdev->dev, "Failed to create context %d\n", rc);
+ valid = false;
+ }
+ }
+
+ mutex_unlock(&hdev->lazy_ctx_creation_lock);
+
+ return valid;
}

/*
diff --git a/drivers/misc/habanalabs/device.c b/drivers/misc/habanalabs/device.c
index 0c4894dd9c02..b63beb73ec76 100644
--- a/drivers/misc/habanalabs/device.c
+++ b/drivers/misc/habanalabs/device.c
@@ -58,8 +58,9 @@ static void hpriv_release(struct kref *ref)
/* Now the FD is really closed */
atomic_dec(&hdev->fd_open_cnt);

- /* This allows a new user context to open the device */
+ mutex_lock(&hdev->lazy_ctx_creation_lock);
hdev->user_ctx = NULL;
+ mutex_unlock(&hdev->lazy_ctx_creation_lock);
}

void hl_hpriv_get(struct hl_fpriv *hpriv)
@@ -233,6 +234,7 @@ static int device_early_init(struct hl_device *hdev)
mutex_init(&hdev->send_cpu_message_lock);
mutex_init(&hdev->debug_lock);
mutex_init(&hdev->mmu_cache_lock);
+ mutex_init(&hdev->lazy_ctx_creation_lock);
INIT_LIST_HEAD(&hdev->hw_queues_mirror_list);
spin_lock_init(&hdev->hw_queues_mirror_lock);
atomic_set(&hdev->in_reset, 0);
@@ -262,6 +264,7 @@ static int device_early_init(struct hl_device *hdev)
*/
static void device_early_fini(struct hl_device *hdev)
{
+ mutex_destroy(&hdev->lazy_ctx_creation_lock);
mutex_destroy(&hdev->mmu_cache_lock);
mutex_destroy(&hdev->debug_lock);
mutex_destroy(&hdev->send_cpu_message_lock);
diff --git a/drivers/misc/habanalabs/habanalabs.h b/drivers/misc/habanalabs/habanalabs.h
index 475cdaa0005e..d0e55839d673 100644
--- a/drivers/misc/habanalabs/habanalabs.h
+++ b/drivers/misc/habanalabs/habanalabs.h
@@ -1183,6 +1183,7 @@ struct hl_device_reset_work {
* @cb_pool: list of preallocated CBs.
* @cb_pool_lock: protects the CB pool.
* @user_ctx: current user context executing.
+ * @lazy_ctx_creation_lock: lock to protect lazy creation of context
* @dram_used_mem: current DRAM memory consumption.
* @timeout_jiffies: device CS timeout value.
* @max_power: the max power of the device, as configured by the sysadmin. This
@@ -1261,6 +1262,7 @@ struct hl_device {

/* TODO: remove user_ctx for multiple process support */
struct hl_ctx *user_ctx;
+ struct mutex lazy_ctx_creation_lock;

atomic64_t dram_used_mem;
u64 timeout_jiffies;
diff --git a/drivers/misc/habanalabs/habanalabs_drv.c b/drivers/misc/habanalabs/habanalabs_drv.c
index 678f61646ca9..b2c52e46e130 100644
--- a/drivers/misc/habanalabs/habanalabs_drv.c
+++ b/drivers/misc/habanalabs/habanalabs_drv.c
@@ -141,12 +141,6 @@ int hl_device_open(struct inode *inode, struct file *filp)
hl_cb_mgr_init(&hpriv->cb_mgr);
hl_ctx_mgr_init(&hpriv->ctx_mgr);

- rc = hl_ctx_create(hdev, hpriv);
- if (rc) {
- dev_err(hdev->dev, "Failed to open FD (CTX fail)\n");
- goto out_err;
- }
-
hpriv->taskpid = find_get_pid(current->pid);

/*
@@ -160,13 +154,6 @@ int hl_device_open(struct inode *inode, struct file *filp)

return 0;

-out_err:
- filp->private_data = NULL;
- hl_ctx_mgr_fini(hpriv->hdev, &hpriv->ctx_mgr);
- hl_cb_mgr_fini(hpriv->hdev, &hpriv->cb_mgr);
- mutex_destroy(&hpriv->restore_phase_mutex);
- kfree(hpriv);
-
close_device:
atomic_dec(&hdev->fd_open_cnt);
return rc;
--
2.17.1
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