habanalabs: remove compute context pointer

It was an error to save the compute context's pointer in the device
structure, as it allowed its use without proper ref-cnt.

Change the variable to a flag that only indicates whether there is
an active compute context. Code that needs the pointer will now
be forced to use proper internal APIs to get the pointer.
Signed-off-by: Oded Gabbay <ogabbay@kernel.org>

drivers/misc/habanalabs/common/context.c

@@ -165,7 +165,7 @@ int hl_ctx_create(struct hl_device *hdev, struct hl_fpriv *hpriv)
 	hpriv->ctx = ctx;
 
 	/* TODO: remove the following line for multiple process support */
-	hdev->compute_ctx = ctx;
+	hdev->is_compute_ctx_active = true;
 
 	return 0;
 

drivers/misc/habanalabs/common/device.c

@@ -97,12 +97,12 @@ static void hpriv_release(struct kref *ref)
 			|| hdev->reset_upon_device_release)
 		hl_device_reset(hdev, HL_DRV_RESET_DEV_RELEASE);
 
-	/* Now we can mark the compute_ctx as empty. Even if a reset is running in a different
+	/* Now we can mark the compute_ctx as not active. Even if a reset is running in a different
 	 * thread, we don't care because the in_reset is marked so if a user will try to open
-	 * the device it will fail on that, even if compute_ctx is NULL.
+	 * the device it will fail on that, even if compute_ctx is false.
 	 */
 	mutex_lock(&hdev->fpriv_list_lock);
-	hdev->compute_ctx = NULL;
+	hdev->is_compute_ctx_active = false;
 	mutex_unlock(&hdev->fpriv_list_lock);
 
 	kfree(hpriv);
@@ -1150,7 +1150,7 @@ int hl_device_reset(struct hl_device *hdev, u32 flags)
 			goto out_err;
 		}
 
-		hdev->compute_ctx = NULL;
+		hdev->is_compute_ctx_active = false;
 
 		rc = hl_ctx_init(hdev, hdev->kernel_ctx, true);
 		if (rc) {
@@ -1403,7 +1403,7 @@ int hl_device_init(struct hl_device *hdev, struct class *hclass)
 		goto mmu_fini;
 	}
 
-	hdev->compute_ctx = NULL;
+	hdev->is_compute_ctx_active = false;
 
 	hdev->asic_funcs->state_dump_init(hdev);
 

drivers/misc/habanalabs/common/habanalabs.h

@@ -2503,7 +2503,6 @@ struct last_error_session_info {
  * @fpriv_list: list of file private data structures. Each structure is created
  *              when a user opens the device
  * @fpriv_list_lock: protects the fpriv_list
- * @compute_ctx: current compute context executing.
  * @aggregated_cs_counters: aggregated cs counters among all contexts
  * @mmu_priv: device-specific MMU data.
  * @mmu_func: device-related MMU functions.
@@ -2601,6 +2600,7 @@ struct last_error_session_info {
  *                        cases where Linux was not loaded to device CPU
  * @supports_wait_for_multi_cs: true if wait for multi CS is supported
  * @is_in_soft_reset: Device is currently in soft reset process.
+ * @is_compute_ctx_active: Whether there is an active compute context executing.
  */
 struct hl_device {
 	struct pci_dev			*pdev;
@@ -2656,8 +2656,6 @@ struct hl_device {
 	struct list_head		fpriv_list;
 	struct mutex			fpriv_list_lock;
 
-	struct hl_ctx			*compute_ctx;
-
 	struct hl_cs_counters_atomic	aggregated_cs_counters;
 
 	struct hl_mmu_priv		mmu_priv;
@@ -2730,6 +2728,7 @@ struct hl_device {
 	u8				supports_wait_for_multi_cs;
 	u8				stream_master_qid_arr_size;
 	u8				is_in_soft_reset;
+	u8				is_compute_ctx_active;
 
 	/* Parameters for bring-up */
 	u64				nic_ports_mask;

drivers/misc/habanalabs/common/habanalabs_drv.c

@@ -161,7 +161,7 @@ int hl_device_open(struct inode *inode, struct file *filp)
 		goto out_err;
 	}
 
-	if (hdev->compute_ctx) {
+	if (hdev->is_compute_ctx_active) {
 		dev_dbg_ratelimited(hdev->dev,
 			"Can't open %s because another user is working on it\n",
 			dev_name(hdev->dev));

drivers/misc/habanalabs/goya/goya.c

 // SPDX-License-Identifier: GPL-2.0
 
 /*
- * Copyright 2016-2019 HabanaLabs, Ltd.
+ * Copyright 2016-2021 HabanaLabs, Ltd.
  * All Rights Reserved.
  */
 
@@ -827,7 +827,7 @@ static void goya_set_freq_to_low_job(struct work_struct *work)
 
 	mutex_lock(&hdev->fpriv_list_lock);
 
-	if (!hdev->compute_ctx)
+	if (!hdev->is_compute_ctx_active)
 		goya_set_frequency(hdev, PLL_LOW);
 
 	mutex_unlock(&hdev->fpriv_list_lock);

drivers/misc/habanalabs/goya/goya_hwmgr.c

 // SPDX-License-Identifier: GPL-2.0
 
 /*
- * Copyright 2016-2019 HabanaLabs, Ltd.
+ * Copyright 2016-2021 HabanaLabs, Ltd.
  * All Rights Reserved.
  */
 
@@ -258,7 +258,7 @@ static ssize_t pm_mng_profile_store(struct device *dev,
 
 	mutex_lock(&hdev->fpriv_list_lock);
 
-	if (hdev->compute_ctx) {
+	if (hdev->is_compute_ctx_active) {
 		dev_err(hdev->dev,
 			"Can't change PM profile while compute context is opened on the device\n");
 		count = -EPERM;