Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754497Ab3JDKma (ORCPT ); Fri, 4 Oct 2013 06:42:30 -0400 Received: from ch1ehsobe001.messaging.microsoft.com ([216.32.181.181]:35688 "EHLO ch1outboundpool.messaging.microsoft.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751149Ab3JDKm2 (ORCPT ); Fri, 4 Oct 2013 06:42:28 -0400 X-Forefront-Antispam-Report: CIP:70.37.183.190;KIP:(null);UIP:(null);IPV:NLI;H:mail.freescale.net;RD:none;EFVD:NLI X-SpamScore: 0 X-BigFish: VS0(zz98dI9371I936eI542I1432Izz1f42h208ch1ee6h1de0h1fdah2073h1202h1e76h1d1ah1d2ah1fc6hzz1de098h17326ah1de097h186068h8275bh8275dha509lz2dh2a8h839h8e2h8e3h93fhd25hf0ah1288h12a5h12a9h12bdh137ah13b6h1441h1504h1537h153bh15d0h162dh1631h1758h18e1h1946h19b5h1ad9h1b0ah1b2fh1fb3h1d0ch1d2eh1d3fh1dfeh1dffh1e1dh1fe8h1ff5hbe9i1155h) From: Bhushan Bharat-R65777 To: Bhushan Bharat-R65777 , Alex Williamson CC: "joro@8bytes.org" , "benh@kernel.crashing.org" , "galak@kernel.crashing.org" , "linux-kernel@vger.kernel.org" , "linuxppc-dev@lists.ozlabs.org" , "linux-pci@vger.kernel.org" , "agraf@suse.de" , Wood Scott-B07421 , "iommu@lists.linux-foundation.org" Subject: RE: [PATCH 2/7] iommu: add api to get iommu_domain of a device Thread-Topic: [PATCH 2/7] iommu: add api to get iommu_domain of a device Thread-Index: AQHOtQsGaQsPvJ8CfEu+dkEJoOsdkZnWszeAgA2xFOCAAAs64A== Date: Fri, 4 Oct 2013 10:42:23 +0000 Message-ID: <6A3DF150A5B70D4F9B66A25E3F7C888D0718FDC3@039-SN2MPN1-011.039d.mgd.msft.net> References: <1379575763-2091-1-git-send-email-Bharat.Bhushan@freescale.com> <1379575763-2091-3-git-send-email-Bharat.Bhushan@freescale.com> <1380127533.3030.319.camel@ul30vt.home> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [10.232.14.2] Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 X-OriginatorOrg: freescale.com X-FOPE-CONNECTOR: Id%0$Dn%*$RO%0$TLS%0$FQDN%$TlsDn% Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from base64 to 8bit by mail.home.local id r94AgbIK011159 Content-Length: 5286 Lines: 132 > -----Original Message----- > From: Bhushan Bharat-R65777 > Sent: Friday, October 04, 2013 3:24 PM > To: 'Alex Williamson' > Cc: joro@8bytes.org; benh@kernel.crashing.org; galak@kernel.crashing.org; linux- > kernel@vger.kernel.org; linuxppc-dev@lists.ozlabs.org; linux- > pci@vger.kernel.org; agraf@suse.de; 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@vger.kernel.org > > [mailto:linux-pci-owner@vger.kernel.org] > > On Behalf Of Alex Williamson > > Sent: Wednesday, September 25, 2013 10:16 PM > > To: Bhushan Bharat-R65777 > > Cc: joro@8bytes.org; benh@kernel.crashing.org; > > galak@kernel.crashing.org; linux- kernel@vger.kernel.org; > > linuxppc-dev@lists.ozlabs.org; linux- pci@vger.kernel.org; > > agraf@suse.de; 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 > > > --- > > > 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@vger.kernel.org More majordomo > > info at http://vger.kernel.org/majordomo-info.html ????{.n?+???????+%?????ݶ??w??{.n?+????{??G?????{ay?ʇڙ?,j??f???h?????????z_??(?階?ݢj"???m??????G????????????&???~???iO???z??v?^?m???? ????????I?