> -----Original Message----- > From: Bhushan Bharat-R65777 > Sent: Friday, October 04, 2013 3:24 PM > To: 'Alex Williamson' > Cc: joro@xxxxxxxxxx; benh@xxxxxxxxxxxxxxxxxxx; galak@xxxxxxxxxxxxxxxxxxx; linux- > kernel@xxxxxxxxxxxxxxx; linuxppc-dev@xxxxxxxxxxxxxxxx; linux- > pci@xxxxxxxxxxxxxxx; agraf@xxxxxxx; Wood Scott-B07421; iommu@lists.linux- > foundation.org > Subject: RE: [PATCH 2/7] iommu: add api to get iommu_domain of a device > > > > > -----Original Message----- > > From: linux-pci-owner@xxxxxxxxxxxxxxx > > [mailto:linux-pci-owner@xxxxxxxxxxxxxxx] > > On Behalf Of Alex Williamson > > Sent: Wednesday, September 25, 2013 10:16 PM > > To: Bhushan Bharat-R65777 > > Cc: joro@xxxxxxxxxx; benh@xxxxxxxxxxxxxxxxxxx; > > galak@xxxxxxxxxxxxxxxxxxx; linux- kernel@xxxxxxxxxxxxxxx; > > linuxppc-dev@xxxxxxxxxxxxxxxx; linux- pci@xxxxxxxxxxxxxxx; > > agraf@xxxxxxx; Wood Scott-B07421; iommu@lists.linux- foundation.org; > > Bhushan Bharat-R65777 > > Subject: Re: [PATCH 2/7] iommu: add api to get iommu_domain of a > > device > > > > On Thu, 2013-09-19 at 12:59 +0530, Bharat Bhushan wrote: > > > This api return the iommu domain to which the device is attached. > > > The iommu_domain is required for making API calls related to iommu. > > > Follow up patches which use this API to know iommu maping. > > > > > > Signed-off-by: Bharat Bhushan <bharat.bhushan@xxxxxxxxxxxxx> > > > --- > > > drivers/iommu/iommu.c | 10 ++++++++++ > > > include/linux/iommu.h | 7 +++++++ > > > 2 files changed, 17 insertions(+), 0 deletions(-) > > > > > > diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c index > > > fbe9ca7..6ac5f50 100644 > > > --- a/drivers/iommu/iommu.c > > > +++ b/drivers/iommu/iommu.c > > > @@ -696,6 +696,16 @@ void iommu_detach_device(struct iommu_domain > > > *domain, struct device *dev) } > > > EXPORT_SYMBOL_GPL(iommu_detach_device); > > > > > > +struct iommu_domain *iommu_get_dev_domain(struct device *dev) { > > > + struct iommu_ops *ops = dev->bus->iommu_ops; > > > + > > > + if (unlikely(ops == NULL || ops->get_dev_iommu_domain == NULL)) > > > + return NULL; > > > + > > > + return ops->get_dev_iommu_domain(dev); } > > > +EXPORT_SYMBOL_GPL(iommu_get_dev_domain); > > > > What prevents this from racing iommu_domain_free()? There's no > > references acquired, so there's no reason for the caller to assume the pointer > is valid. > > Sorry for late query, somehow this email went into a folder and escaped; > > Just to be sure, there is not lock at generic "struct iommu_domain", but IP > specific structure (link FSL domain) linked in iommu_domain->priv have a lock, > so we need to ensure this race in FSL iommu code (say > drivers/iommu/fsl_pamu_domain.c), right? Further thinking of this, there are more problems here: - Like MSI subsystem will call iommu_get_dev_domain(), which will take a lock, find the domain pointer, release the lock, and return the domain - Now if domain in freed up - While MSI subsystem tries to do work on domain (like get_attribute/set_attribute etc) ??? So can we do like iommu_get_dev_domain() will return domain with the lock held, and iommu_put_dev_domain() will release the lock? And iommu_get_dev_domain() must always be followed by iommu_get_dev_domain() Thanks -Bharat > > Thanks > -Bharat > > > > > > /* > > > * IOMMU groups are really the natrual working unit of the IOMMU, but > > > * the IOMMU API works on domains and devices. Bridge that gap by > > > diff --git a/include/linux/iommu.h b/include/linux/iommu.h index > > > 7ea319e..fa046bd 100644 > > > --- a/include/linux/iommu.h > > > +++ b/include/linux/iommu.h > > > @@ -127,6 +127,7 @@ struct iommu_ops { > > > int (*domain_set_windows)(struct iommu_domain *domain, u32 w_count); > > > /* Get the numer of window per domain */ > > > u32 (*domain_get_windows)(struct iommu_domain *domain); > > > + struct iommu_domain *(*get_dev_iommu_domain)(struct device *dev); > > > > > > unsigned long pgsize_bitmap; > > > }; > > > @@ -190,6 +191,7 @@ extern int iommu_domain_window_enable(struct > > > iommu_domain > > *domain, u32 wnd_nr, > > > phys_addr_t offset, u64 size, > > > int prot); > > > extern void iommu_domain_window_disable(struct iommu_domain > > > *domain, > > > u32 wnd_nr); > > > +extern struct iommu_domain *iommu_get_dev_domain(struct device > > > +*dev); > > > /** > > > * report_iommu_fault() - report about an IOMMU fault to the IOMMU > framework > > > * @domain: the iommu domain where the fault has happened @@ -284,6 > > > +286,11 @@ static inline void iommu_domain_window_disable(struct > > > iommu_domain *domain, { } > > > > > > +static inline struct iommu_domain *iommu_get_dev_domain(struct > > > +device > > > +*dev) { > > > + return NULL; > > > +} > > > + > > > static inline phys_addr_t iommu_iova_to_phys(struct iommu_domain > > > *domain, dma_addr_t iova) { > > > return 0; > > > > > > > > -- > > To unsubscribe from this list: send the line "unsubscribe linux-pci" > > in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo > > info at http://vger.kernel.org/majordomo-info.html ��.n��������+%������w��{.n�����{���"�)�� jg��� �����ݢj����G���� ���j:+v���w�m������w�������h�����٥
