Re: [PATCH] ntb: no sleep in ntb_async_tx_submit

[Dave Jiang <dave.jiang@intel.com>]

On 06/09/2017 03:06 PM, Allen Hubbe wrote:
> Do not sleep in ntb_async_tx_submit, which could deadlock.
> This reverts commit "8c874cc140d667f84ae4642bb5b5e0d6396d2ca4"
> 
> Fixes: 8c874cc140d667f84ae4642bb5b5e0d6396d2ca4
> 
> Reported-by: Jia-Ju Bai <baijiaju1990@163.com>
> Signed-off-by: Allen Hubbe <Allen.Hubbe@dell.com>

Acked-by: Dave Jiang <dave.jiang@intel.com>

> ---
>  drivers/ntb/ntb_transport.c | 50 +++++++--------------------------------------
>  1 file changed, 7 insertions(+), 43 deletions(-)
> 
> diff --git a/drivers/ntb/ntb_transport.c b/drivers/ntb/ntb_transport.c
> index 5b6b00ea6ed9..10e5bf460139 100644
> --- a/drivers/ntb/ntb_transport.c
> +++ b/drivers/ntb/ntb_transport.c
> @@ -177,14 +177,12 @@ struct ntb_transport_qp {
>  	u64 rx_err_ver;
>  	u64 rx_memcpy;
>  	u64 rx_async;
> -	u64 dma_rx_prep_err;
>  	u64 tx_bytes;
>  	u64 tx_pkts;
>  	u64 tx_ring_full;
>  	u64 tx_err_no_buf;
>  	u64 tx_memcpy;
>  	u64 tx_async;
> -	u64 dma_tx_prep_err;
>  };
>  
>  struct ntb_transport_mw {
> @@ -254,8 +252,6 @@ enum {
>  #define QP_TO_MW(nt, qp)	((qp) % nt->mw_count)
>  #define NTB_QP_DEF_NUM_ENTRIES	100
>  #define NTB_LINK_DOWN_TIMEOUT	10
> -#define DMA_RETRIES		20
> -#define DMA_OUT_RESOURCE_TO	msecs_to_jiffies(50)
>  
>  static void ntb_transport_rxc_db(unsigned long data);
>  static const struct ntb_ctx_ops ntb_transport_ops;
> @@ -516,12 +512,6 @@ static ssize_t debugfs_read(struct file *filp, char __user *ubuf, size_t count,
>  	out_offset += snprintf(buf + out_offset, out_count - out_offset,
>  			       "free tx - \t%u\n",
>  			       ntb_transport_tx_free_entry(qp));
> -	out_offset += snprintf(buf + out_offset, out_count - out_offset,
> -			       "DMA tx prep err - \t%llu\n",
> -			       qp->dma_tx_prep_err);
> -	out_offset += snprintf(buf + out_offset, out_count - out_offset,
> -			       "DMA rx prep err - \t%llu\n",
> -			       qp->dma_rx_prep_err);
>  
>  	out_offset += snprintf(buf + out_offset, out_count - out_offset,
>  			       "\n");
> @@ -768,8 +758,6 @@ static void ntb_qp_link_down_reset(struct ntb_transport_qp *qp)
>  	qp->tx_err_no_buf = 0;
>  	qp->tx_memcpy = 0;
>  	qp->tx_async = 0;
> -	qp->dma_tx_prep_err = 0;
> -	qp->dma_rx_prep_err = 0;
>  }
>  
>  static void ntb_qp_link_cleanup(struct ntb_transport_qp *qp)
> @@ -1317,7 +1305,6 @@ static int ntb_async_rx_submit(struct ntb_queue_entry *entry, void *offset)
>  	struct dmaengine_unmap_data *unmap;
>  	dma_cookie_t cookie;
>  	void *buf = entry->buf;
> -	int retries = 0;
>  
>  	len = entry->len;
>  	device = chan->device;
> @@ -1346,22 +1333,11 @@ static int ntb_async_rx_submit(struct ntb_queue_entry *entry, void *offset)
>  
>  	unmap->from_cnt = 1;
>  
> -	for (retries = 0; retries < DMA_RETRIES; retries++) {
> -		txd = device->device_prep_dma_memcpy(chan,
> -						     unmap->addr[1],
> -						     unmap->addr[0], len,
> -						     DMA_PREP_INTERRUPT);
> -		if (txd)
> -			break;
> -
> -		set_current_state(TASK_INTERRUPTIBLE);
> -		schedule_timeout(DMA_OUT_RESOURCE_TO);
> -	}
> -
> -	if (!txd) {
> -		qp->dma_rx_prep_err++;
> +	txd = device->device_prep_dma_memcpy(chan, unmap->addr[1],
> +					     unmap->addr[0], len,
> +					     DMA_PREP_INTERRUPT);
> +	if (!txd)
>  		goto err_get_unmap;
> -	}
>  
>  	txd->callback_result = ntb_rx_copy_callback;
>  	txd->callback_param = entry;
> @@ -1606,7 +1582,6 @@ static int ntb_async_tx_submit(struct ntb_transport_qp *qp,
>  	struct dmaengine_unmap_data *unmap;
>  	dma_addr_t dest;
>  	dma_cookie_t cookie;
> -	int retries = 0;
>  
>  	device = chan->device;
>  	dest = qp->tx_mw_phys + qp->tx_max_frame * entry->tx_index;
> @@ -1628,21 +1603,10 @@ static int ntb_async_tx_submit(struct ntb_transport_qp *qp,
>  
>  	unmap->to_cnt = 1;
>  
> -	for (retries = 0; retries < DMA_RETRIES; retries++) {
> -		txd = device->device_prep_dma_memcpy(chan, dest,
> -						     unmap->addr[0], len,
> -						     DMA_PREP_INTERRUPT);
> -		if (txd)
> -			break;
> -
> -		set_current_state(TASK_INTERRUPTIBLE);
> -		schedule_timeout(DMA_OUT_RESOURCE_TO);
> -	}
> -
> -	if (!txd) {
> -		qp->dma_tx_prep_err++;
> +	txd = device->device_prep_dma_memcpy(chan, dest, unmap->addr[0], len,
> +					     DMA_PREP_INTERRUPT);
> +	if (!txd)
>  		goto err_get_unmap;
> -	}
>  
>  	txd->callback_result = ntb_tx_copy_callback;
>  	txd->callback_param = entry;
>