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

From: Alexey Kardashevskiy
Date: Thu Apr 16 2015 - 12:29:42 EST


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
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/