Re: Re: [PATCH] iommu/arm-smmu: Fix arm_smmu_device refcount leak when arm_smmu_rpm_get fails
Thanks for your advice, I'll send a v2 patch soon.
> -Original Messages-
> From: "Robin Murphy"
> Sent Time: 2021-06-09 22:12:11 (Wednesday)
> To: "Xiyu Yang" , "Will Deacon" ,
> "Joerg Roedel" , "Nicolin Chen" ,
> "Bjorn Andersson" , "Krishna Reddy"
> , "Jordan Crouse" , "Sai Prakash
> Ranjan" ,
> linux-arm-ker...@lists.infradead.org, iommu@lists.linux-foundation.org,
> linux-ker...@vger.kernel.org
> Cc: yuanxzh...@fudan.edu.cn, "Xin Tan"
> 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
> > Signed-off-by: Xin Tan
> > ---
> > 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 >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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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
Signed-off-by: Xin Tan
---
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 >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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[PATCH] iommu/arm-smmu: Fix arm_smmu_device refcount leak when arm_smmu_rpm_get fails
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.
Signed-off-by: Xiyu Yang
Signed-off-by: Xin Tan
---
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 >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);
--
2.7.4
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