Re: [PATCH rdma-rc] RDMA/usnic: Lock VF with mutex instead of spinlock

[Haakon Bugge <haakon.bugge@oracle.com>]

> On 13 Sep 2021, at 10:04, Leon Romanovsky <leon@kernel.org> wrote:
> 
> From: Leon Romanovsky <leonro@nvidia.com>
> 
> Usnic VF doesn't need lock in atomic context to create QPs, so it is safe
> to use mutex instead of spinlock. Such change fixes the following smatch
> error.

s/GFP_ATOMIC/GFP_KERNEL/ in find_free_vf_and_create_qp_grp() as well?


Thxs, Håkon
> 
> Smatch static checker warning:
> 
>   lib/kobject.c:289 kobject_set_name_vargs()
>    warn: sleeping in atomic context
> 
> Fixes: 514aee660df4 ("RDMA: Globally allocate and release QP memory")
> Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
> Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
> ---
> drivers/infiniband/hw/usnic/usnic_ib.h       |  2 +-
> drivers/infiniband/hw/usnic/usnic_ib_main.c  |  2 +-
> drivers/infiniband/hw/usnic/usnic_ib_verbs.c | 16 ++++++++--------
> 3 files changed, 10 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/infiniband/hw/usnic/usnic_ib.h b/drivers/infiniband/hw/usnic/usnic_ib.h
> index 84dd682d2334..b350081aeb5a 100644
> --- a/drivers/infiniband/hw/usnic/usnic_ib.h
> +++ b/drivers/infiniband/hw/usnic/usnic_ib.h
> @@ -90,7 +90,7 @@ struct usnic_ib_dev {
> 
> struct usnic_ib_vf {
> 	struct usnic_ib_dev		*pf;
> -	spinlock_t			lock;
> +	struct mutex			lock;
> 	struct usnic_vnic		*vnic;
> 	unsigned int			qp_grp_ref_cnt;
> 	struct usnic_ib_pd		*pd;
> diff --git a/drivers/infiniband/hw/usnic/usnic_ib_main.c b/drivers/infiniband/hw/usnic/usnic_ib_main.c
> index 228e9a36dad0..d346dd48e731 100644
> --- a/drivers/infiniband/hw/usnic/usnic_ib_main.c
> +++ b/drivers/infiniband/hw/usnic/usnic_ib_main.c
> @@ -572,7 +572,7 @@ static int usnic_ib_pci_probe(struct pci_dev *pdev,
> 	}
> 
> 	vf->pf = pf;
> -	spin_lock_init(&vf->lock);
> +	mutex_init(&vf->lock);
> 	mutex_lock(&pf->usdev_lock);
> 	list_add_tail(&vf->link, &pf->vf_dev_list);
> 	/*
> diff --git a/drivers/infiniband/hw/usnic/usnic_ib_verbs.c b/drivers/infiniband/hw/usnic/usnic_ib_verbs.c
> index 06a4e9d4545d..756a83bcff58 100644
> --- a/drivers/infiniband/hw/usnic/usnic_ib_verbs.c
> +++ b/drivers/infiniband/hw/usnic/usnic_ib_verbs.c
> @@ -196,7 +196,7 @@ find_free_vf_and_create_qp_grp(struct ib_qp *qp,
> 		for (i = 0; dev_list[i]; i++) {
> 			dev = dev_list[i];
> 			vf = dev_get_drvdata(dev);
> -			spin_lock(&vf->lock);
> +			mutex_lock(&vf->lock);
> 			vnic = vf->vnic;
> 			if (!usnic_vnic_check_room(vnic, res_spec)) {
> 				usnic_dbg("Found used vnic %s from %s\n",
> @@ -208,10 +208,10 @@ find_free_vf_and_create_qp_grp(struct ib_qp *qp,
> 							     vf, pd, res_spec,
> 							     trans_spec);
> 
> -				spin_unlock(&vf->lock);
> +				mutex_unlock(&vf->lock);
> 				goto qp_grp_check;
> 			}
> -			spin_unlock(&vf->lock);
> +			mutex_unlock(&vf->lock);
> 
> 		}
> 		usnic_uiom_free_dev_list(dev_list);
> @@ -220,7 +220,7 @@ find_free_vf_and_create_qp_grp(struct ib_qp *qp,
> 
> 	/* Try to find resources on an unused vf */
> 	list_for_each_entry(vf, &us_ibdev->vf_dev_list, link) {
> -		spin_lock(&vf->lock);
> +		mutex_lock(&vf->lock);
> 		vnic = vf->vnic;
> 		if (vf->qp_grp_ref_cnt == 0 &&
> 		    usnic_vnic_check_room(vnic, res_spec) == 0) {
> @@ -228,10 +228,10 @@ find_free_vf_and_create_qp_grp(struct ib_qp *qp,
> 						     vf, pd, res_spec,
> 						     trans_spec);
> 
> -			spin_unlock(&vf->lock);
> +			mutex_unlock(&vf->lock);
> 			goto qp_grp_check;
> 		}
> -		spin_unlock(&vf->lock);
> +		mutex_unlock(&vf->lock);
> 	}
> 
> 	usnic_info("No free qp grp found on %s\n",
> @@ -253,9 +253,9 @@ static void qp_grp_destroy(struct usnic_ib_qp_grp *qp_grp)
> 
> 	WARN_ON(qp_grp->state != IB_QPS_RESET);
> 
> -	spin_lock(&vf->lock);
> +	mutex_lock(&vf->lock);
> 	usnic_ib_qp_grp_destroy(qp_grp);
> -	spin_unlock(&vf->lock);
> +	mutex_unlock(&vf->lock);
> }
> 
> static int create_qp_validate_user_data(struct usnic_ib_create_qp_cmd cmd)
> -- 
> 2.31.1
>