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Date:   Thu, 30 Nov 2023 13:51:59 +0530
From:   Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
To:     mhi@lists.linux.dev
Cc:     linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org,
        Alex Elder <elder@linaro.org>
Subject: Re: [PATCH] bus: mhi: ep: Use slab allocator where applicable
Message-ID: <20231130082159.GK3043@thinkpad>
References: <20231018122812.47261-1-manivannan.sadhasivam@linaro.org>
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In-Reply-To: <20231018122812.47261-1-manivannan.sadhasivam@linaro.org>
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On Wed, Oct 18, 2023 at 05:58:12PM +0530, Manivannan Sadhasivam wrote:
> 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>

Applied to mhi-next!

- Mani

> ---
>  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
> 

-- 
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