Re: [PATCH -next] iommu/dma: Fix missing mutex_init() in iommu_get_msi_cookie()

[Robin Murphy]

On 2022-07-15 08:49, Joerg Roedel wrote:
> Adding Robin.
>
> On Mon, Jun 27, 2022 at 04:55:33PM +0800, Yang Yingliang wrote:
> > cookie_alloc() is called by iommu_get_dma_cookie() and iommu_get_msi_cookie(),
> > but the mutex is only initialized in iommu_get_dma_cookie(), move mutex_init()
> > into cookie_alloc() to make sure the mutex will be initialized.

The mutex is only used in iommu_dma_init_domain(), which is only called 
by iommu_setup_dma_ops() for IOMMU_DOMAIN_DMA domains. How is there a 
problem here?

Robin.

> > Fixes: ac9a5d522bb8 ("iommu/dma: Fix race condition during iova_domain initialization")
> > Reported-by: Hulk Robot <hulkci@xxxxxxxxxx>
> > Signed-off-by: Yang Yingliang <yangyingliang@xxxxxxxxxx>
> > ---
> >   drivers/iommu/dma-iommu.c | 2 +-
> >   1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
> > index 1910f4f1612b..e29157380c48 100644
> > --- a/drivers/iommu/dma-iommu.c
> > +++ b/drivers/iommu/dma-iommu.c
> > @@ -294,6 +294,7 @@ static struct iommu_dma_cookie *cookie_alloc(enum iommu_dma_cookie_type type)
> >   	if (cookie) {
> >   		INIT_LIST_HEAD(&cookie->msi_page_list);
> >   		cookie->type = type;
> > +		mutex_init(&cookie->mutex);
> >   	}
> >   	return cookie;
> >   }
> > @@ -311,7 +312,6 @@ int iommu_get_dma_cookie(struct iommu_domain *domain)
> >   	if (!domain->iova_cookie)
> >   		return -ENOMEM;
> >   
> > -	mutex_init(&domain->iova_cookie->mutex);
> >   	return 0;
> >   }
> >   
> > --
> > 2.25.1