Messages in this thread | | | Subject | Re: [PATCH] iommu/arm-smmu: Fix arm_smmu_device refcount leak when arm_smmu_rpm_get fails | From | Robin Murphy <> | Date | Wed, 9 Jun 2021 15:12:11 +0100 |
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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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