linux-kernel - RE: [PATCH vfio 1/2] hisi_acc_vfio_pci: Change reset_lock to mutex

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Message-ID: <eb2172d1e24044059e65d15b10391f65@huawei.com>
Date:   Fri, 24 Nov 2023 08:46:58 +0000
From:   Shameerali Kolothum Thodi <shameerali.kolothum.thodi@...wei.com>
To:     Brett Creeley <brett.creeley@....com>,
        "jgg@...pe.ca" <jgg@...pe.ca>,
        "yishaih@...dia.com" <yishaih@...dia.com>,
        liulongfang <liulongfang@...wei.com>,
        "kevin.tian@...el.com" <kevin.tian@...el.com>,
        "alex.williamson@...hat.com" <alex.williamson@...hat.com>,
        "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
CC:     "shannon.nelson@....com" <shannon.nelson@....com>
Subject: RE: [PATCH vfio 1/2] hisi_acc_vfio_pci: Change reset_lock to
 mutex_lock



> -----Original Message-----
> From: Brett Creeley [mailto:brett.creeley@....com]
> Sent: 22 November 2023 19:37
> To: jgg@...pe.ca; yishaih@...dia.com; liulongfang
> <liulongfang@...wei.com>; Shameerali Kolothum Thodi
> <shameerali.kolothum.thodi@...wei.com>; kevin.tian@...el.com;
> alex.williamson@...hat.com; kvm@...r.kernel.org;
> linux-kernel@...r.kernel.org
> Cc: shannon.nelson@....com; brett.creeley@....com
> Subject: [PATCH vfio 1/2] hisi_acc_vfio_pci: Change reset_lock to mutex_lock
> 
> Based on comments from other vfio vendors and the
> maintainer the vfio/pds driver changed the reset_lock
> to a mutex_lock. As part of that change it was requested
> that the other vendor drivers be changed as well. So,
> make the change.
> 
> The comment that requested the change for reference:
> https://lore.kernel.org/kvm/BN9PR11MB52769E037CB356AB15A0D9B88CA
> 0A@...PR11MB5276.namprd11.prod.outlook.com/
> 
> Also, make checkpatch happy by moving the lock comment.
> 
> Signed-off-by: Brett Creeley <brett.creeley@....com>
> ---
>  drivers/vfio/pci/hisilicon/hisi_acc_vfio_pci.c | 13 +++++++------
>  drivers/vfio/pci/hisilicon/hisi_acc_vfio_pci.h |  3 +--
>  2 files changed, 8 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/vfio/pci/hisilicon/hisi_acc_vfio_pci.c
> b/drivers/vfio/pci/hisilicon/hisi_acc_vfio_pci.c
> index b2f9778c8366..2c049b8de4b4 100644
> --- a/drivers/vfio/pci/hisilicon/hisi_acc_vfio_pci.c
> +++ b/drivers/vfio/pci/hisilicon/hisi_acc_vfio_pci.c
> @@ -638,17 +638,17 @@ static void
>  hisi_acc_vf_state_mutex_unlock(struct hisi_acc_vf_core_device
> *hisi_acc_vdev)
>  {
>  again:
> -	spin_lock(&hisi_acc_vdev->reset_lock);
> +	mutex_lock(&hisi_acc_vdev->reset_mutex);
>  	if (hisi_acc_vdev->deferred_reset) {
>  		hisi_acc_vdev->deferred_reset = false;
> -		spin_unlock(&hisi_acc_vdev->reset_lock);
> +		mutex_unlock(&hisi_acc_vdev->reset_mutex);

Don't think we have that sleeping while atomic case for this here.
Same for mlx5 as well. But if the idea is to have a common locking
across vendor drivers, it is fine.

Reviewed-by: Shameer Kolothum <shameerali.kolothum.thodi@...wei.com>

Thanks,
Shameer

>  		hisi_acc_vdev->vf_qm_state = QM_NOT_READY;
>  		hisi_acc_vdev->mig_state = VFIO_DEVICE_STATE_RUNNING;
>  		hisi_acc_vf_disable_fds(hisi_acc_vdev);
>  		goto again;
>  	}
>  	mutex_unlock(&hisi_acc_vdev->state_mutex);
> -	spin_unlock(&hisi_acc_vdev->reset_lock);
> +	mutex_unlock(&hisi_acc_vdev->reset_mutex);
>  }
> 
>  static void hisi_acc_vf_start_device(struct hisi_acc_vf_core_device
> *hisi_acc_vdev)
> @@ -1108,13 +1108,13 @@ static void
> hisi_acc_vf_pci_aer_reset_done(struct pci_dev *pdev)
>  	 * In case the state_mutex was taken already we defer the cleanup work
>  	 * to the unlock flow of the other running context.
>  	 */
> -	spin_lock(&hisi_acc_vdev->reset_lock);
> +	mutex_lock(&hisi_acc_vdev->reset_mutex);
>  	hisi_acc_vdev->deferred_reset = true;
>  	if (!mutex_trylock(&hisi_acc_vdev->state_mutex)) {
> -		spin_unlock(&hisi_acc_vdev->reset_lock);
> +		mutex_unlock(&hisi_acc_vdev->reset_mutex);
>  		return;
>  	}
> -	spin_unlock(&hisi_acc_vdev->reset_lock);
> +	mutex_unlock(&hisi_acc_vdev->reset_mutex);
>  	hisi_acc_vf_state_mutex_unlock(hisi_acc_vdev);
>  }
> 
> @@ -1350,6 +1350,7 @@ static int hisi_acc_vfio_pci_migrn_init_dev(struct
> vfio_device *core_vdev)
>  	hisi_acc_vdev->pf_qm = pf_qm;
>  	hisi_acc_vdev->vf_dev = pdev;
>  	mutex_init(&hisi_acc_vdev->state_mutex);
> +	mutex_init(&hisi_acc_vdev->reset_mutex);
> 
>  	core_vdev->migration_flags = VFIO_MIGRATION_STOP_COPY |
> VFIO_MIGRATION_PRE_COPY;
>  	core_vdev->mig_ops = &hisi_acc_vfio_pci_migrn_state_ops;
> diff --git a/drivers/vfio/pci/hisilicon/hisi_acc_vfio_pci.h
> b/drivers/vfio/pci/hisilicon/hisi_acc_vfio_pci.h
> index dcabfeec6ca1..ed5ab332d0f3 100644
> --- a/drivers/vfio/pci/hisilicon/hisi_acc_vfio_pci.h
> +++ b/drivers/vfio/pci/hisilicon/hisi_acc_vfio_pci.h
> @@ -109,8 +109,7 @@ struct hisi_acc_vf_core_device {
>  	struct hisi_qm vf_qm;
>  	u32 vf_qm_state;
>  	int vf_id;
> -	/* For reset handler */
> -	spinlock_t reset_lock;
> +	struct mutex reset_mutex; /* For reset handler */
>  	struct hisi_acc_vf_migration_file *resuming_migf;
>  	struct hisi_acc_vf_migration_file *saving_migf;
>  };
> --
> 2.17.1