From: "Xiyu Yang" <19210240158@fudan.edu.cn>
To: "Robin Murphy" <robin.murphy@arm.com>
Cc: "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,
yuanxzhang@fudan.edu.cn, "Xin Tan" <tanxin.ctf@gmail.com>
Subject: Re: Re: [PATCH] iommu/arm-smmu: Fix arm_smmu_device refcount leak when arm_smmu_rpm_get fails
Date: Thu, 10 Jun 2021 10:20:24 +0800 (GMT+08:00) [thread overview]
Message-ID: <3da0a67a.3d4d.179f3b87d02.Coremail.19210240158@fudan.edu.cn> (raw)
In-Reply-To: <e5b8d7f6-862e-bca4-a1e9-35e0de47440e@arm.com>
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);
> >
> >
prev parent reply other threads:[~2021-06-10 2:21 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-09 13:35 [PATCH] iommu/arm-smmu: Fix arm_smmu_device refcount leak when arm_smmu_rpm_get fails Xiyu Yang
2021-06-09 14:12 ` Robin Murphy
2021-06-10 2:20 ` Xiyu Yang [this message]
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