RE: [PATCH v3 1/6] iommu/msm: Add missing __disable_clocks calls

[Tian, Kevin]

> From: Nicolin Chen <nicolinc@xxxxxxxxxx>
> Sent: Wednesday, September 21, 2022 2:47 AM
> 
> On Tue, Sep 20, 2022 at 06:15:21AM +0000, Tian, Kevin wrote:
> > External email: Use caution opening links or attachments
> >
> >
> > > From: Nicolin Chen <nicolinc@xxxxxxxxxx>
> > > Sent: Thursday, September 15, 2022 3:56 PM
> > >
> > > The clock is not symmetrically disabled in the error-out routines.
> > >
> > > Fixes: 109bd48ea2e1 ("iommu/msm: Add DT adaptation")
> > > Cc: stable@xxxxxxxxxxxxxxx
> > > Cc: Sricharan R <sricharan@xxxxxxxxxxxxxx>
> > > Cc: Andy Gross <agross@xxxxxxxxxx>
> > > Cc: Bjorn Andersson <bjorn.andersson@xxxxxxxxxx>
> > > Cc: Konrad Dybcio <konrad.dybcio@xxxxxxxxxxxxxx>
> > > Signed-off-by: Nicolin Chen <nicolinc@xxxxxxxxxx>
> > > ---
> > >  drivers/iommu/msm_iommu.c | 2 ++
> > >  1 file changed, 2 insertions(+)
> > >
> > > diff --git a/drivers/iommu/msm_iommu.c
> b/drivers/iommu/msm_iommu.c
> > > index 6a24aa804ea3..a7d41ba4a47b 100644
> > > --- a/drivers/iommu/msm_iommu.c
> > > +++ b/drivers/iommu/msm_iommu.c
> > > @@ -418,6 +418,7 @@ static int msm_iommu_attach_dev(struct
> > > iommu_domain *domain, struct device *dev)
> > >                       list_for_each_entry(master, &iommu->ctx_list, list) {
> > >                               if (master->num) {
> > >                                       dev_err(dev, "domain already
> > > attached");
> > > +                                     __disable_clocks(iommu);
> > >                                       ret = -EEXIST;
> > >                                       goto fail;
> > >                               }
> > > @@ -425,6 +426,7 @@ static int msm_iommu_attach_dev(struct
> > > iommu_domain *domain, struct device *dev)
> > >                                       msm_iommu_alloc_ctx(iommu-
> > > >context_map,
> > >                                                           0, iommu->ncb);
> > >                               if (IS_ERR_VALUE(master->num)) {
> > > +                                     __disable_clocks(iommu);
> >
> > also need to free_ctx() for already walked nodes.
> 
> Oooo...yes. Probably could reuse the detach() -- [1].
> 
> > btw it's a bit weird that although here is coded based on a list
> > in reality there is at most one node per list. According to
> > insert_iommu_master() a master object is allocated and inserted
> > to the ctx_list only if the ctx_list is currently empty...
> 
> Yea. The insert_iommu_master() indicates that there would be only
> one master on a cts_list, while the rest part of the driver tries
> to take care of a potential multi-master per cts_list case, which
> practically won't happen by looking at the DT file. But the driver
> existed for the legacy platform data configuration too, so I don't
> intend to change too much...

it's also problematic that it assumes that the attached device
must be the first master in the list. But anyway I agree to not
change too much given that mess.

> 
> Thanks!
> Nic
> 
> [1]
> diff --git a/drivers/iommu/msm_iommu.c b/drivers/iommu/msm_iommu.c
> index 6a24aa804ea3..30c5662e24bc 100644
> --- a/drivers/iommu/msm_iommu.c
> +++ b/drivers/iommu/msm_iommu.c
> @@ -394,6 +394,33 @@ static struct iommu_device
> *msm_iommu_probe_device(struct device *dev)
>  	return &iommu->iommu;
>  }
> 
> +static void msm_iommu_detach_dev(struct iommu_domain *domain,
> +				 struct device *dev)
> +{
> +	struct msm_priv *priv = to_msm_priv(domain);
> +	unsigned long flags;
> +	struct msm_iommu_dev *iommu;
> +	struct msm_iommu_ctx_dev *master;
> +	int ret;
> +
> +	free_io_pgtable_ops(priv->iop);
> +
> +	spin_lock_irqsave(&msm_iommu_lock, flags);
> +	list_for_each_entry(iommu, &priv->list_attached, dom_node) {
> +		ret = __enable_clocks(iommu);
> +		if (ret)
> +			goto fail;
> +
> +		list_for_each_entry(master, &iommu->ctx_list, list) {
> +			msm_iommu_free_ctx(iommu->context_map,
> master->num);
> +			__reset_context(iommu->base, master->num);
> +		}
> +		__disable_clocks(iommu);
> +	}
> +fail:
> +	spin_unlock_irqrestore(&msm_iommu_lock, flags);
> +}
> +
>  static int msm_iommu_attach_dev(struct iommu_domain *domain, struct
> device *dev)
>  {
>  	int ret = 0;
> @@ -418,13 +445,15 @@ static int msm_iommu_attach_dev(struct
> iommu_domain *domain, struct device *dev)
>  			list_for_each_entry(master, &iommu->ctx_list, list) {
>  				if (master->num) {
>  					dev_err(dev, "domain already
> attached");
> +					__disable_clocks(iommu);
>  					ret = -EEXIST;
>  					goto fail;
>  				}
>  				master->num =
>  					msm_iommu_alloc_ctx(iommu-
> >context_map,
>  							    0, iommu->ncb);
> -				if (IS_ERR_VALUE(master->num)) {
> +				if (master->num < 0) {
> +					__disable_clocks(iommu);
>  					ret = -ENODEV;
>  					goto fail;
>  				}
> @@ -439,37 +468,12 @@ static int msm_iommu_attach_dev(struct
> iommu_domain *domain, struct device *dev)
> 
>  fail:
>  	spin_unlock_irqrestore(&msm_iommu_lock, flags);
> +	if (ret)
> +		msm_iommu_detach_dev(domain, dev);
> 
>  	return ret;
>  }
> 
> -static void msm_iommu_detach_dev(struct iommu_domain *domain,
> -				 struct device *dev)
> -{
> -	struct msm_priv *priv = to_msm_priv(domain);
> -	unsigned long flags;
> -	struct msm_iommu_dev *iommu;
> -	struct msm_iommu_ctx_dev *master;
> -	int ret;
> -
> -	free_io_pgtable_ops(priv->iop);
> -
> -	spin_lock_irqsave(&msm_iommu_lock, flags);
> -	list_for_each_entry(iommu, &priv->list_attached, dom_node) {
> -		ret = __enable_clocks(iommu);
> -		if (ret)
> -			goto fail;
> -
> -		list_for_each_entry(master, &iommu->ctx_list, list) {
> -			msm_iommu_free_ctx(iommu->context_map,
> master->num);
> -			__reset_context(iommu->base, master->num);
> -		}
> -		__disable_clocks(iommu);
> -	}
> -fail:
> -	spin_unlock_irqrestore(&msm_iommu_lock, flags);
> -}
> -
>  static int msm_iommu_map(struct iommu_domain *domain, unsigned long
> iova,
>  			 phys_addr_t pa, size_t len, int prot, gfp_t gfp)
>  {