powerpc/powernv: Reference iommu_table while it is linked to a group

aik · mpe · commit 847e6563aa8c · 2018-12-21T16:20:46.000+11:00
The iommu_table pointer stored in iommu_table_group may get stale
by accident, this adds referencing and removes a redundant comment
about this.

Signed-off-by: Alexey Kardashevskiy &lt;aik@ozlabs.ru&gt;
Reviewed-by: David Gibson &lt;david@gibson.dropbear.id.au&gt;
Signed-off-by: Michael Ellerman &lt;mpe@ellerman.id.au&gt;
diff --git a/arch/powerpc/platforms/powernv/pci-ioda-tce.c b/arch/powerpc/platforms/powernv/pci-ioda-tce.c
@@ -368,6 +368,7 @@ void pnv_pci_unlink_table_and_group(struct iommu_table *tbl,
 	found = false;
 	for (i = 0; i < IOMMU_TABLE_GROUP_MAX_TABLES; ++i) {
 		if (table_group->tables[i] == tbl) {
+			iommu_tce_table_put(tbl);
 			table_group->tables[i] = NULL;
 			found = true;
 			break;
@@ -393,7 +394,7 @@ long pnv_pci_link_table_and_group(int node, int num,
 	tgl->table_group = table_group;
 	list_add_rcu(&tgl->next, &tbl->it_group_list);
 
-	table_group->tables[num] = tbl;
+	table_group->tables[num] = iommu_tce_table_get(tbl);
 
 	return 0;
 }
diff --git a/arch/powerpc/platforms/powernv/pci-ioda.c b/arch/powerpc/platforms/powernv/pci-ioda.c
@@ -2714,10 +2714,6 @@ static long pnv_pci_ioda2_npu_unset_window(
 
 static void pnv_ioda2_npu_take_ownership(struct iommu_table_group *table_group)
 {
-	/*
-	 * Detach NPU first as pnv_ioda2_take_ownership() will destroy
-	 * the iommu_table if 32bit DMA is enabled.
-	 */
 	pnv_npu_take_ownership(gpe_table_group_to_npe(table_group));
 	pnv_ioda2_take_ownership(table_group);
 }

Original file line number	Diff line number	Diff line change
`@@ -2714,10 +2714,6 @@ static long pnv_pci_ioda2_npu_unset_window(`
`2714`	`2714`
`2715`	`2715`	`static void pnv_ioda2_npu_take_ownership(struct iommu_table_group *table_group)`
`2716`	`2716`	`{`
`2717`		`- /*`
`2718`		`- * Detach NPU first as pnv_ioda2_take_ownership() will destroy`
`2719`		`- * the iommu_table if 32bit DMA is enabled.`
`2720`		`- */`
`2721`	`2717`	`pnv_npu_take_ownership(gpe_table_group_to_npe(table_group));`
`2722`	`2718`	`pnv_ioda2_take_ownership(table_group);`
`2723`	`2719`	`}`