[PATCH kernel] powerpc/powernv/ioda2: Remove redundand free of TCE pages

[PATCH kernel] powerpc/powernv/ioda2: Remove redundand free of TCE pages

[Alexey Kardashevskiy]

When IODA2 creates a PE, it creates an IOMMU table with it_ops::free
set to pnv_ioda2_table_free() which calls pnv_pci_ioda2_table_free_pages().

Since iommu_tce_table_put() calls it_ops::free when the last reference
to the table is released, explicit call to pnv_pci_ioda2_table_free_pages()
is not needed so let's remove it.

This should fix double free in the case of PCI hotuplug as
pnv_pci_ioda2_table_free_pages() does not reset neither
iommu_table::it_base nor ::it_size.

This was not exposed by SRIOV as it uses different code path via
pnv_pcibios_sriov_disable().

IODA1 does not inialize it_ops::free so it does not have this issue.

Fixes: c5f7700bb "powerpc/powernv: Dynamically release PE"
Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
---

We have not seen any bug reports because we have not tested the actual
PCI hotunplug in hardware very well.


---
 arch/powerpc/platforms/powernv/pci-ioda.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/arch/powerpc/platforms/powernv/pci-ioda.c b/arch/powerpc/platforms/powernv/pci-ioda.c
index 9731098..92ca662 100644
--- a/arch/powerpc/platforms/powernv/pci-ioda.c
+++ b/arch/powerpc/platforms/powernv/pci-ioda.c
@@ -3670,7 +3670,6 @@ static void pnv_pci_ioda2_release_pe_dma(struct pnv_ioda_pe *pe)
 		WARN_ON(pe->table_group.group);
 	}
 
-	pnv_pci_ioda2_table_free_pages(tbl);
 	iommu_tce_table_put(tbl);
 }
 
-- 
2.11.0

Re: [kernel] powerpc/powernv/ioda2: Remove redundand free of TCE pages

[Michael Ellerman]

On Wed, 2018-05-30 at 09:22:50 UTC, Alexey Kardashevskiy wrote:
> When IODA2 creates a PE, it creates an IOMMU table with it_ops::free
> set to pnv_ioda2_table_free() which calls pnv_pci_ioda2_table_free_pages().
> 
> Since iommu_tce_table_put() calls it_ops::free when the last reference
> to the table is released, explicit call to pnv_pci_ioda2_table_free_pages()
> is not needed so let's remove it.
> 
> This should fix double free in the case of PCI hotuplug as
> pnv_pci_ioda2_table_free_pages() does not reset neither
> iommu_table::it_base nor ::it_size.
> 
> This was not exposed by SRIOV as it uses different code path via
> pnv_pcibios_sriov_disable().
> 
> IODA1 does not inialize it_ops::free so it does not have this issue.
> 
> Fixes: c5f7700bb "powerpc/powernv: Dynamically release PE"
> Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>

Applied to powerpc next, thanks.

https://git.kernel.org/powerpc/c/98fd72fe82527fd26618062b60cfd3

cheers