On 04/16/2015 04:46 PM, David Gibson wrote:

On Fri, Apr 10, 2015 at 04:31:03PM +1000, Alexey Kardashevskiy wrote:

quoted

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.

quoted

Signed-off-by: Alexey Kardashevskiy <redacted>
---
  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