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    SubjectRe: [PATCH kernel v10 05/34] powerpc/iommu: Always release iommu_table in iommu_free_table()
    On Wed, 13 May 2015 16:30:16 +1000
    Alexey Kardashevskiy <aik@ozlabs.ru> wrote:

    > On 05/13/2015 03:33 PM, Gavin Shan wrote:
    > > On Tue, May 12, 2015 at 01:38:54AM +1000, Alexey Kardashevskiy wrote:
    > >> At the moment iommu_free_table() only releases memory if
    > >> the table was initialized for the platform code use, i.e. it had
    > >> it_map initialized (which purpose is to track DMA memory space use).
    > >>
    > >> With dynamic DMA windows, we will need to be able to release
    > >> iommu_table even if it was used for VFIO in which case it_map is NULL
    > >> so does the patch.
    > >>
    > >> Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
    > >
    > > Reviewed-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
    > >
    > >> ---
    > >> arch/powerpc/kernel/iommu.c | 3 +--
    > >> 1 file changed, 1 insertion(+), 2 deletions(-)
    > >>
    > >> diff --git a/arch/powerpc/kernel/iommu.c b/arch/powerpc/kernel/iommu.c
    > >> index 3d47eb3..2c02d4c 100644
    > >> --- a/arch/powerpc/kernel/iommu.c
    > >> +++ b/arch/powerpc/kernel/iommu.c
    > >> @@ -714,8 +714,7 @@ void iommu_free_table(struct iommu_table *tbl, const char *node_name)
    > >> unsigned int order;
    > >>
    > >> if (!tbl || !tbl->it_map) {
    > >> - printk(KERN_ERR "%s: expected TCE map for %s\n", __func__,
    > >> - node_name);
    > >> + kfree(tbl);
    > >
    > > I'm not sure if the "tbl" needs to be checked against NULL as kfree() already
    > > has the check. But it looks a bit strange to free NULL "tbl" from the code
    > > itself.
    >
    > Yeah, looks a bit weird, agree, I'll change but in general kfree/vfree/...
    > - they all check the passed pointer for NULL.

    But if tbl is NULL, the tbl->it_map check will fail, won't it? So in
    this case, I think you have to keep it.

    Thomas


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