Re: [PATCH kernel v8 21/31] powerpc/iommu: Split iommu_free_table into 2 helpers

[Alexey Kardashevskiy]

On 04/16/2015 04:46 PM, David Gibson wrote:
> On Fri, Apr 10, 2015 at 04:31:03PM +1000, Alexey Kardashevskiy wrote:
> > The iommu_free_table helper release memory it is using (the TCE table and
> > @it_map) and release the iommu_table struct as well. We might not want
> > the very last step as we store iommu_table in parent structures.
>
> Yeah, as I commented on the earlier patch, freeing the surrounding
> group from a function taking just the individual table is wrong.


This is iommu tables created by the old code which stores these iommu_table 
struct pointers in device nodes. I believe there is a plan to get rid of 
iommu tables there and when this is done, this workaround will be gone.


> > Signed-off-by: Alexey Kardashevskiy <aik@xxxxxxxxx>
> > ---
> >   arch/powerpc/include/asm/iommu.h |  1 +
> >   arch/powerpc/kernel/iommu.c      | 57 ++++++++++++++++++++++++----------------
> >   2 files changed, 35 insertions(+), 23 deletions(-)
> >
> > diff --git a/arch/powerpc/include/asm/iommu.h b/arch/powerpc/include/asm/iommu.h
> > index bde7ee7..8ed4648 100644
> > --- a/arch/powerpc/include/asm/iommu.h
> > +++ b/arch/powerpc/include/asm/iommu.h
> > @@ -127,6 +127,7 @@ static inline void *get_iommu_table_base(struct device *dev)
> >
> >   extern struct iommu_table *iommu_table_alloc(int node);
> >   /* Frees table for an individual device node */
> > +extern void iommu_reset_table(struct iommu_table *tbl, const char *node_name);
> >   extern void iommu_free_table(struct iommu_table *tbl, const char *node_name);
> >
> >   /* Initializes an iommu_table based in values set in the passed-in
> > diff --git a/arch/powerpc/kernel/iommu.c b/arch/powerpc/kernel/iommu.c
> > index 501e8ee..0bcd988 100644
> > --- a/arch/powerpc/kernel/iommu.c
> > +++ b/arch/powerpc/kernel/iommu.c
> > @@ -721,24 +721,46 @@ struct iommu_table *iommu_table_alloc(int node)
> >   	return &table_group->tables[0];
> >   }
> >
> > +void iommu_reset_table(struct iommu_table *tbl, const char *node_name)
> > +{
> > +	if (!tbl)
> > +		return;
> > +
> > +	if (tbl->it_map) {
> > +		unsigned long bitmap_sz;
> > +		unsigned int order;
> > +
> > +		/*
> > +		 * In case we have reserved the first bit, we should not emit
> > +		 * the warning below.
> > +		 */
> > +		if (tbl->it_offset == 0)
> > +			clear_bit(0, tbl->it_map);
> > +
> > +		/* verify that table contains no entries */
> > +		if (!bitmap_empty(tbl->it_map, tbl->it_size))
> > +			pr_warn("%s: Unexpected TCEs for %s\n", __func__,
> > +					node_name);
> > +
> > +		/* calculate bitmap size in bytes */
> > +		bitmap_sz = BITS_TO_LONGS(tbl->it_size) * sizeof(unsigned long);
> > +
> > +		/* free bitmap */
> > +		order = get_order(bitmap_sz);
> > +		free_pages((unsigned long) tbl->it_map, order);
> > +	}
> > +
> > +	memset(tbl, 0, sizeof(*tbl));
> > +}
> > +
> >   void iommu_free_table(struct iommu_table *tbl, const char *node_name)
> >   {
> > -	unsigned long bitmap_sz;
> > -	unsigned int order;
> >   	struct iommu_table_group *table_group = tbl->it_group;
> >
> > -	if (!tbl || !tbl->it_map) {
> > -		printk(KERN_ERR "%s: expected TCE map for %s\n", __func__,
> > -				node_name);
> > +	if (!tbl)
> >   		return;
> > -	}
> >
> > -	/*
> > -	 * In case we have reserved the first bit, we should not emit
> > -	 * the warning below.
> > -	 */
> > -	if (tbl->it_offset == 0)
> > -		clear_bit(0, tbl->it_map);
> > +	iommu_reset_table(tbl, node_name);
> >
> >   #ifdef CONFIG_IOMMU_API
> >   	if (table_group->group) {
> > @@ -747,17 +769,6 @@ void iommu_free_table(struct iommu_table *tbl, const char *node_name)
> >   	}
> >   #endif
> >
> > -	/* verify that table contains no entries */
> > -	if (!bitmap_empty(tbl->it_map, tbl->it_size))
> > -		pr_warn("%s: Unexpected TCEs for %s\n", __func__, node_name);
> > -
> > -	/* calculate bitmap size in bytes */
> > -	bitmap_sz = BITS_TO_LONGS(tbl->it_size) * sizeof(unsigned long);
> > -
> > -	/* free bitmap */
> > -	order = get_order(bitmap_sz);
> > -	free_pages((unsigned long) tbl->it_map, order);
> > -
> >   	/* free table */
> >   	kfree(table_group);
> >   }


--
Alexey
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