Re: [PATCH v3 03/15] NTB: ntb_transport: Make link setup flags atomic

[Dave Jiang]

On 9/28/26 8:25 AM, Koichiro Den wrote:
> Convert nt->link_is_up and qp->client_ready to atomic_t and use atomic
> accessors throughout. This prepares for the unlocked cleanup check and
> the link-up ordering fixes that follow.
> 
> Leave control flow and locking unchanged.
> 
> Cc: stable@xxxxxxxxxxxxxxx
> Suggested-by: Frank Li <Frank.Li@xxxxxxxxxx>
> Signed-off-by: Koichiro Den <den@xxxxxxxxxxxxx>

Reviewed-by: Dave Jiang <dave.jiang@xxxxxxxxx>

> ---
> Changes in v3:
>   - New patch. (Frank)
>     https://lore.kernel.org/r/i3b4kyeuwyjssav2kne5uhxmltwl2bmug2weyfaujxtrwlkuox@ms6ozb55tmz5/
> 
>  drivers/ntb/ntb_transport.c | 31 ++++++++++++++++---------------
>  1 file changed, 16 insertions(+), 15 deletions(-)
> 
> diff --git a/drivers/ntb/ntb_transport.c b/drivers/ntb/ntb_transport.c
> index 55a20ae9a85e..5d2ec484c3df 100644
> --- a/drivers/ntb/ntb_transport.c
> +++ b/drivers/ntb/ntb_transport.c
> @@ -47,6 +47,7 @@
>   * Contact Information:
>   * Jon Mason <jon.mason@xxxxxxxxx>
>   */
> +#include <linux/atomic.h>
>  #include <linux/debugfs.h>
>  #include <linux/delay.h>
>  #include <linux/dmaengine.h>
> @@ -142,7 +143,7 @@ struct ntb_transport_qp {
>  	struct dma_chan *tx_dma_chan;
>  	struct dma_chan *rx_dma_chan;
>  
> -	bool client_ready;
> +	atomic_t client_ready;
>  	bool link_is_up;
>  	bool active;
>  
> @@ -249,7 +250,7 @@ struct ntb_transport_ctx {
>  	unsigned int msi_spad_offset;
>  	u64 msi_db_mask;
>  
> -	bool link_is_up;
> +	atomic_t link_is_up;
>  	struct delayed_work link_work;
>  	struct work_struct link_cleanup;
>  
> @@ -945,7 +946,7 @@ static void ntb_qp_link_cleanup_work(struct work_struct *work)
>  
>  	ntb_qp_link_cleanup(qp);
>  
> -	if (nt->link_is_up)
> +	if (atomic_read(&nt->link_is_up))
>  		schedule_delayed_work(&qp->link_work,
>  				      msecs_to_jiffies(NTB_LINK_DOWN_TIMEOUT));
>  }
> @@ -972,7 +973,7 @@ static void ntb_transport_link_cleanup(struct ntb_transport_ctx *nt)
>  			cancel_delayed_work_sync(&qp->link_work);
>  		}
>  
> -	if (!nt->link_is_up)
> +	if (!atomic_read(&nt->link_is_up))
>  		cancel_delayed_work_sync(&nt->link_work);
>  
>  	for (i = 0; i < nt->mw_count; i++)
> @@ -1084,7 +1085,7 @@ static void ntb_transport_link_work(struct work_struct *work)
>  			goto out1;
>  	}
>  
> -	nt->link_is_up = true;
> +	atomic_set(&nt->link_is_up, true);
>  
>  	for (i = 0; i < nt->qp_count; i++) {
>  		struct ntb_transport_qp *qp = &nt->qp_vec[i];
> @@ -1092,7 +1093,7 @@ static void ntb_transport_link_work(struct work_struct *work)
>  		ntb_transport_setup_qp_mw(nt, i);
>  		ntb_transport_setup_qp_peer_msi(nt, i);
>  
> -		if (qp->client_ready)
> +		if (atomic_read(&qp->client_ready))
>  			schedule_delayed_work(&qp->link_work, 0);
>  	}
>  
> @@ -1121,7 +1122,7 @@ static void ntb_qp_link_work(struct work_struct *work)
>  	struct ntb_transport_ctx *nt = qp->transport;
>  	int val;
>  
> -	WARN_ON(!nt->link_is_up);
> +	WARN_ON(!atomic_read(&nt->link_is_up));
>  
>  	val = ntb_spad_read(nt->ndev, QP_LINKS);
>  
> @@ -1141,7 +1142,7 @@ static void ntb_qp_link_work(struct work_struct *work)
>  
>  		if (qp->active)
>  			tasklet_schedule(&qp->rxc_db_work);
> -	} else if (nt->link_is_up)
> +	} else if (atomic_read(&nt->link_is_up))
>  		schedule_delayed_work(&qp->link_work,
>  				      msecs_to_jiffies(NTB_LINK_DOWN_TIMEOUT));
>  }
> @@ -1165,7 +1166,7 @@ static int ntb_transport_init_queue(struct ntb_transport_ctx *nt,
>  	qp->qp_num = qp_num;
>  	qp->transport = nt;
>  	qp->ndev = nt->ndev;
> -	qp->client_ready = false;
> +	atomic_set(&qp->client_ready, false);
>  	qp->event_handler = NULL;
>  	ntb_qp_link_context_reset(qp);
>  
> @@ -1373,7 +1374,7 @@ static int ntb_transport_probe(struct ntb_client *self, struct ntb_dev *ndev)
>  	if (rc)
>  		goto err3;
>  
> -	nt->link_is_up = false;
> +	atomic_set(&nt->link_is_up, false);
>  	ntb_link_enable(ndev, NTB_SPEED_AUTO, NTB_WIDTH_AUTO);
>  	ntb_link_event(ndev);
>  
> @@ -1457,7 +1458,7 @@ static void ntb_complete_rxc(struct ntb_transport_qp *qp)
>  
>  		spin_unlock_irqrestore(&qp->ntb_rx_q_lock, irqflags);
>  
> -		if (qp->rx_handler && qp->client_ready)
> +		if (qp->rx_handler && atomic_read(&qp->client_ready))
>  			qp->rx_handler(qp, qp->cb_data, cb_data, len);
>  
>  		spin_lock_irqsave(&qp->ntb_rx_q_lock, irqflags);
> @@ -2268,7 +2269,7 @@ void *ntb_transport_rx_remove(struct ntb_transport_qp *qp, unsigned int *len)
>  	struct ntb_queue_entry *entry;
>  	void *buf;
>  
> -	if (!qp || qp->client_ready)
> +	if (!qp || atomic_read(&qp->client_ready))
>  		return NULL;
>  
>  	entry = ntb_list_rm(&qp->ntb_rx_q_lock, &qp->rx_pend_q);
> @@ -2385,9 +2386,9 @@ void ntb_transport_link_up(struct ntb_transport_qp *qp)
>  	if (!qp)
>  		return;
>  
> -	qp->client_ready = true;
> +	atomic_set(&qp->client_ready, true);
>  
> -	if (qp->transport->link_is_up)
> +	if (atomic_read(&qp->transport->link_is_up))
>  		schedule_delayed_work(&qp->link_work, 0);
>  }
>  EXPORT_SYMBOL_GPL(ntb_transport_link_up);
> @@ -2407,7 +2408,7 @@ void ntb_transport_link_down(struct ntb_transport_qp *qp)
>  	if (!qp)
>  		return;
>  
> -	qp->client_ready = false;
> +	atomic_set(&qp->client_ready, false);
>  
>  	val = ntb_spad_read(qp->ndev, QP_LINKS);
>