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From:   Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
To:     mhi@lists.linux.dev
Cc:     linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org,
        Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>,
        Alex Elder <elder@linaro.org>
Subject: [PATCH] bus: mhi: ep: Use slab allocator where applicable
Date:   Wed, 18 Oct 2023 17:58:12 +0530
Message-Id: <20231018122812.47261-1-manivannan.sadhasivam@linaro.org>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

Use slab allocator for allocating the memory for objects used frequently
and are of fixed size. This reduces the overheard associated with
kmalloc().

Suggested-by: Alex Elder <elder@linaro.org>
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
---
 drivers/bus/mhi/ep/main.c | 70 +++++++++++++++++++++++++++++----------
 include/linux/mhi_ep.h    |  3 ++
 2 files changed, 56 insertions(+), 17 deletions(-)

diff --git a/drivers/bus/mhi/ep/main.c b/drivers/bus/mhi/ep/main.c
index 66ca470bf302..834e7afadd64 100644
--- a/drivers/bus/mhi/ep/main.c
+++ b/drivers/bus/mhi/ep/main.c
@@ -71,7 +71,8 @@ static int mhi_ep_send_event(struct mhi_ep_cntrl *mhi_cntrl, u32 ring_idx,
 static int mhi_ep_send_completion_event(struct mhi_ep_cntrl *mhi_cntrl, struct mhi_ep_ring *ring,
 					struct mhi_ring_element *tre, u32 len, enum mhi_ev_ccs code)
 {
-	struct mhi_ring_element *event = kzalloc(sizeof(struct mhi_ring_element), GFP_KERNEL);
+	struct mhi_ring_element *event = kmem_cache_zalloc(mhi_cntrl->ev_ring_el_cache,
+							   GFP_KERNEL | GFP_DMA);
 	int ret;
 
 	event->ptr = cpu_to_le64(ring->rbase + ring->rd_offset * sizeof(*tre));
@@ -79,42 +80,45 @@ static int mhi_ep_send_completion_event(struct mhi_ep_cntrl *mhi_cntrl, struct m
 	event->dword[1] = MHI_TRE_EV_DWORD1(ring->ch_id, MHI_PKT_TYPE_TX_EVENT);
 
 	ret = mhi_ep_send_event(mhi_cntrl, ring->er_index, event, MHI_TRE_DATA_GET_BEI(tre));
-	kfree(event);
+	kmem_cache_free(mhi_cntrl->ev_ring_el_cache, event);
 
 	return ret;
 }
 
 int mhi_ep_send_state_change_event(struct mhi_ep_cntrl *mhi_cntrl, enum mhi_state state)
 {
-	struct mhi_ring_element *event = kzalloc(sizeof(struct mhi_ring_element), GFP_KERNEL);
+	struct mhi_ring_element *event = kmem_cache_zalloc(mhi_cntrl->ev_ring_el_cache,
+							   GFP_KERNEL | GFP_DMA);
 	int ret;
 
 	event->dword[0] = MHI_SC_EV_DWORD0(state);
 	event->dword[1] = MHI_SC_EV_DWORD1(MHI_PKT_TYPE_STATE_CHANGE_EVENT);
 
 	ret = mhi_ep_send_event(mhi_cntrl, 0, event, 0);
-	kfree(event);
+	kmem_cache_free(mhi_cntrl->ev_ring_el_cache, event);
 
 	return ret;
 }
 
 int mhi_ep_send_ee_event(struct mhi_ep_cntrl *mhi_cntrl, enum mhi_ee_type exec_env)
 {
-	struct mhi_ring_element *event = kzalloc(sizeof(struct mhi_ring_element), GFP_KERNEL);
+	struct mhi_ring_element *event = kmem_cache_zalloc(mhi_cntrl->ev_ring_el_cache,
+							   GFP_KERNEL | GFP_DMA);
 	int ret;
 
 	event->dword[0] = MHI_EE_EV_DWORD0(exec_env);
 	event->dword[1] = MHI_SC_EV_DWORD1(MHI_PKT_TYPE_EE_EVENT);
 
 	ret = mhi_ep_send_event(mhi_cntrl, 0, event, 0);
-	kfree(event);
+	kmem_cache_free(mhi_cntrl->ev_ring_el_cache, event);
 
 	return ret;
 }
 
 static int mhi_ep_send_cmd_comp_event(struct mhi_ep_cntrl *mhi_cntrl, enum mhi_ev_ccs code)
 {
-	struct mhi_ring_element *event = kzalloc(sizeof(struct mhi_ring_element), GFP_KERNEL);
+	struct mhi_ring_element *event = kmem_cache_zalloc(mhi_cntrl->ev_ring_el_cache,
+							   GFP_KERNEL | GFP_DMA);
 	struct mhi_ep_ring *ring = &mhi_cntrl->mhi_cmd->ring;
 	int ret;
 
@@ -123,7 +127,7 @@ static int mhi_ep_send_cmd_comp_event(struct mhi_ep_cntrl *mhi_cntrl, enum mhi_e
 	event->dword[1] = MHI_CC_EV_DWORD1(MHI_PKT_TYPE_CMD_COMPLETION_EVENT);
 
 	ret = mhi_ep_send_event(mhi_cntrl, 0, event, 0);
-	kfree(event);
+	kmem_cache_free(mhi_cntrl->ev_ring_el_cache, event);
 
 	return ret;
 }
@@ -435,7 +439,7 @@ static int mhi_ep_process_ch_ring(struct mhi_ep_ring *ring, struct mhi_ring_elem
 		mhi_chan->xfer_cb(mhi_chan->mhi_dev, &result);
 	} else {
 		/* UL channel */
-		result.buf_addr = kzalloc(len, GFP_KERNEL);
+		result.buf_addr = kmem_cache_zalloc(mhi_cntrl->tre_buf_cache, GFP_KERNEL | GFP_DMA);
 		if (!result.buf_addr)
 			return -ENOMEM;
 
@@ -443,7 +447,7 @@ static int mhi_ep_process_ch_ring(struct mhi_ep_ring *ring, struct mhi_ring_elem
 			ret = mhi_ep_read_channel(mhi_cntrl, ring, &result, len);
 			if (ret < 0) {
 				dev_err(&mhi_chan->mhi_dev->dev, "Failed to read channel\n");
-				kfree(result.buf_addr);
+				kmem_cache_free(mhi_cntrl->tre_buf_cache, result.buf_addr);
 				return ret;
 			}
 
@@ -455,7 +459,7 @@ static int mhi_ep_process_ch_ring(struct mhi_ep_ring *ring, struct mhi_ring_elem
 			/* Read until the ring becomes empty */
 		} while (!mhi_ep_queue_is_empty(mhi_chan->mhi_dev, DMA_TO_DEVICE));
 
-		kfree(result.buf_addr);
+		kmem_cache_free(mhi_cntrl->tre_buf_cache, result.buf_addr);
 	}
 
 	return 0;
@@ -764,14 +768,14 @@ static void mhi_ep_ch_ring_worker(struct work_struct *work)
 		if (ret) {
 			dev_err(dev, "Error updating write offset for ring\n");
 			mutex_unlock(&chan->lock);
-			kfree(itr);
+			kmem_cache_free(mhi_cntrl->ring_item_cache, itr);
 			continue;
 		}
 
 		/* Sanity check to make sure there are elements in the ring */
 		if (ring->rd_offset == ring->wr_offset) {
 			mutex_unlock(&chan->lock);
-			kfree(itr);
+			kmem_cache_free(mhi_cntrl->ring_item_cache, itr);
 			continue;
 		}
 
@@ -783,12 +787,12 @@ static void mhi_ep_ch_ring_worker(struct work_struct *work)
 			dev_err(dev, "Error processing ring for channel (%u): %d\n",
 				ring->ch_id, ret);
 			mutex_unlock(&chan->lock);
-			kfree(itr);
+			kmem_cache_free(mhi_cntrl->ring_item_cache, itr);
 			continue;
 		}
 
 		mutex_unlock(&chan->lock);
-		kfree(itr);
+		kmem_cache_free(mhi_cntrl->ring_item_cache, itr);
 	}
 }
 
@@ -844,7 +848,7 @@ static void mhi_ep_queue_channel_db(struct mhi_ep_cntrl *mhi_cntrl, unsigned lon
 		u32 ch_id = ch_idx + i;
 
 		ring = &mhi_cntrl->mhi_chan[ch_id].ring;
-		item = kzalloc(sizeof(*item), GFP_ATOMIC);
+		item = kmem_cache_zalloc(mhi_cntrl->ring_item_cache, GFP_ATOMIC);
 		if (!item)
 			return;
 
@@ -1391,6 +1395,29 @@ int mhi_ep_register_controller(struct mhi_ep_cntrl *mhi_cntrl,
 		goto err_free_ch;
 	}
 
+	mhi_cntrl->ev_ring_el_cache = kmem_cache_create("mhi_ep_event_ring_el",
+							sizeof(struct mhi_ring_element), 0,
+							SLAB_CACHE_DMA, NULL);
+	if (!mhi_cntrl->ev_ring_el_cache) {
+		ret = -ENOMEM;
+		goto err_free_cmd;
+	}
+
+	mhi_cntrl->tre_buf_cache = kmem_cache_create("mhi_ep_tre_buf", MHI_EP_DEFAULT_MTU, 0,
+						      SLAB_CACHE_DMA, NULL);
+	if (!mhi_cntrl->tre_buf_cache) {
+		ret = -ENOMEM;
+		goto err_destroy_ev_ring_el_cache;
+	}
+
+	mhi_cntrl->ring_item_cache = kmem_cache_create("mhi_ep_ring_item",
+							sizeof(struct mhi_ep_ring_item), 0,
+							0, NULL);
+	if (!mhi_cntrl->ev_ring_el_cache) {
+		ret = -ENOMEM;
+		goto err_destroy_tre_buf_cache;
+	}
+
 	INIT_WORK(&mhi_cntrl->state_work, mhi_ep_state_worker);
 	INIT_WORK(&mhi_cntrl->reset_work, mhi_ep_reset_worker);
 	INIT_WORK(&mhi_cntrl->cmd_ring_work, mhi_ep_cmd_ring_worker);
@@ -1399,7 +1426,7 @@ int mhi_ep_register_controller(struct mhi_ep_cntrl *mhi_cntrl,
 	mhi_cntrl->wq = alloc_workqueue("mhi_ep_wq", 0, 0);
 	if (!mhi_cntrl->wq) {
 		ret = -ENOMEM;
-		goto err_free_cmd;
+		goto err_destroy_ring_item_cache;
 	}
 
 	INIT_LIST_HEAD(&mhi_cntrl->st_transition_list);
@@ -1458,6 +1485,12 @@ int mhi_ep_register_controller(struct mhi_ep_cntrl *mhi_cntrl,
 	ida_free(&mhi_ep_cntrl_ida, mhi_cntrl->index);
 err_destroy_wq:
 	destroy_workqueue(mhi_cntrl->wq);
+err_destroy_ring_item_cache:
+	kmem_cache_destroy(mhi_cntrl->ring_item_cache);
+err_destroy_ev_ring_el_cache:
+	kmem_cache_destroy(mhi_cntrl->ev_ring_el_cache);
+err_destroy_tre_buf_cache:
+	kmem_cache_destroy(mhi_cntrl->tre_buf_cache);
 err_free_cmd:
 	kfree(mhi_cntrl->mhi_cmd);
 err_free_ch:
@@ -1479,6 +1512,9 @@ void mhi_ep_unregister_controller(struct mhi_ep_cntrl *mhi_cntrl)
 
 	free_irq(mhi_cntrl->irq, mhi_cntrl);
 
+	kmem_cache_destroy(mhi_cntrl->tre_buf_cache);
+	kmem_cache_destroy(mhi_cntrl->ev_ring_el_cache);
+	kmem_cache_destroy(mhi_cntrl->ring_item_cache);
 	kfree(mhi_cntrl->mhi_cmd);
 	kfree(mhi_cntrl->mhi_chan);
 
diff --git a/include/linux/mhi_ep.h b/include/linux/mhi_ep.h
index f198a8ac7ee7..ce85d42b685d 100644
--- a/include/linux/mhi_ep.h
+++ b/include/linux/mhi_ep.h
@@ -128,6 +128,9 @@ struct mhi_ep_cntrl {
 	struct work_struct reset_work;
 	struct work_struct cmd_ring_work;
 	struct work_struct ch_ring_work;
+	struct kmem_cache *ring_item_cache;
+	struct kmem_cache *ev_ring_el_cache;
+	struct kmem_cache *tre_buf_cache;
 
 	void (*raise_irq)(struct mhi_ep_cntrl *mhi_cntrl, u32 vector);
 	int (*alloc_map)(struct mhi_ep_cntrl *mhi_cntrl, u64 pci_addr, phys_addr_t *phys_ptr,
-- 
2.25.1