Messages in this thread | | | Date | Thu, 10 Jun 2021 10:20:24 +0800 (GMT+08:00) | From | "Xiyu Yang" <> | Subject | Re: Re: [PATCH] iommu/arm-smmu: Fix arm_smmu_device refcount leak when arm_smmu_rpm_get fails |
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Thanks for your advice, I'll send a v2 patch soon.
> -----Original Messages----- > From: "Robin Murphy" <robin.murphy@arm.com> > Sent Time: 2021-06-09 22:12:11 (Wednesday) > To: "Xiyu Yang" <xiyuyang19@fudan.edu.cn>, "Will Deacon" <will@kernel.org>, "Joerg Roedel" <joro@8bytes.org>, "Nicolin Chen" <nicoleotsuka@gmail.com>, "Bjorn Andersson" <bjorn.andersson@linaro.org>, "Krishna Reddy" <vdumpa@nvidia.com>, "Jordan Crouse" <jordan@cosmicpenguin.net>, "Sai Prakash Ranjan" <saiprakash.ranjan@codeaurora.org>, linux-arm-kernel@lists.infradead.org, iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org > Cc: yuanxzhang@fudan.edu.cn, "Xin Tan" <tanxin.ctf@gmail.com> > Subject: Re: [PATCH] iommu/arm-smmu: Fix arm_smmu_device refcount leak when arm_smmu_rpm_get fails > > On 2021-06-09 14:35, Xiyu Yang wrote: > > arm_smmu_rpm_get() invokes pm_runtime_get_sync(), which increases the > > refcount of the "smmu" even though the return value is less than 0. > > > > The reference counting issue happens in some error handling paths of > > arm_smmu_rpm_get() in its caller functions. When arm_smmu_rpm_get() > > fails, the caller functions forget to decrease the refcount of "smmu" > > increased by arm_smmu_rpm_get(), causing a refcount leak. > > > > Fix this issue by calling arm_smmu_rpm_put() or jumping to the "rpm_put" > > label when arm_smmu_rpm_get() fails. > > If only there was some kind of helper function which could encapsulate > the correct expected behaviour in a single place... > > In fact with the new pm_runtime_resume_and_get() API I think these two > patches boil down to a one-line change. > > Thanks, > Robin. > > > Signed-off-by: Xiyu Yang <xiyuyang19@fudan.edu.cn> > > Signed-off-by: Xin Tan <tanxin.ctf@gmail.com> > > --- > > drivers/iommu/arm/arm-smmu/arm-smmu.c | 13 +++++++++---- > > 1 file changed, 9 insertions(+), 4 deletions(-) > > > > diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu.c b/drivers/iommu/arm/arm-smmu/arm-smmu.c > > index 6f72c4d208ca..177ee54c5534 100644 > > --- a/drivers/iommu/arm/arm-smmu/arm-smmu.c > > +++ b/drivers/iommu/arm/arm-smmu/arm-smmu.c > > @@ -840,7 +840,7 @@ static void arm_smmu_destroy_domain_context(struct iommu_domain *domain) > > > > ret = arm_smmu_rpm_get(smmu); > > if (ret < 0) > > - return; > > + goto rpm_put; > > > > /* > > * Disable the context bank and free the page tables before freeing > > @@ -857,6 +857,7 @@ static void arm_smmu_destroy_domain_context(struct iommu_domain *domain) > > free_io_pgtable_ops(smmu_domain->pgtbl_ops); > > __arm_smmu_free_bitmap(smmu->context_map, cfg->cbndx); > > > > +rpm_put: > > arm_smmu_rpm_put(smmu); > > } > > > > @@ -1153,7 +1154,7 @@ static int arm_smmu_attach_dev(struct iommu_domain *domain, struct device *dev) > > > > ret = arm_smmu_rpm_get(smmu); > > if (ret < 0) > > - return ret; > > + goto rpm_put; > > > > /* Ensure that the domain is finalised */ > > ret = arm_smmu_init_domain_context(domain, smmu, dev); > > @@ -1404,7 +1405,7 @@ static struct iommu_device *arm_smmu_probe_device(struct device *dev) > > > > ret = arm_smmu_rpm_get(smmu); > > if (ret < 0) > > - goto out_cfg_free; > > + goto rpm_put; > > > > ret = arm_smmu_master_alloc_smes(dev); > > arm_smmu_rpm_put(smmu); > > @@ -1417,6 +1418,8 @@ static struct iommu_device *arm_smmu_probe_device(struct device *dev) > > > > return &smmu->iommu; > > > > +rpm_put: > > + arm_smmu_rpm_put(smmu); > > out_cfg_free: > > kfree(cfg); > > out_free: > > @@ -1438,8 +1441,10 @@ static void arm_smmu_release_device(struct device *dev) > > smmu = cfg->smmu; > > > > ret = arm_smmu_rpm_get(smmu); > > - if (ret < 0) > > + if (ret < 0) { > > + arm_smmu_rpm_put(smmu); > > return; > > + } > > > > arm_smmu_master_free_smes(cfg, fwspec); > > > >
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