To simplify struct page, the page pool members of struct page should be
moved to other, allowing these members to be removed from struct page.
Introduce a network memory descriptor to store the members, struct
netmem_desc, reusing struct net_iov that already mirrored struct page.
While at it, add a static assert to prevent the size of struct
netmem_desc from getting bigger that might conflict with other members
within struct page.
Signed-off-by: Byungchul Park <byungchul@xxxxxx>
---
include/net/netmem.h | 41 +++++++++++++++++++++++++++++++++++------
1 file changed, 35 insertions(+), 6 deletions(-)
diff --git a/include/net/netmem.h b/include/net/netmem.h
index 386164fb9c18..a721f9e060a2 100644
--- a/include/net/netmem.h
+++ b/include/net/netmem.h
@@ -31,12 +31,34 @@ enum net_iov_type {
};
struct net_iov {
- enum net_iov_type type;
- unsigned long pp_magic;
- struct page_pool *pp;
- struct net_iov_area *owner;
- unsigned long dma_addr;
- atomic_long_t pp_ref_count;
+ /*
+ * XXX: Now that struct netmem_desc overlays on struct page,
+ * struct_group_tagged() should cover all of them. However,
+ * a separate struct netmem_desc should be declared and embedded,
+ * once struct netmem_desc is no longer overlayed but it has its
+ * own instance from slab. The final form should be:
+ *
+ * struct netmem_desc {
+ * unsigned long pp_magic;
+ * struct page_pool *pp;
+ * unsigned long dma_addr;
+ * atomic_long_t pp_ref_count;
+ * };
+ *
+ * struct net_iov {
+ * enum net_iov_type type;
+ * struct net_iov_area *owner;
+ * struct netmem_desc;
+ * };
+ */
+ struct_group_tagged(netmem_desc, desc,
+ enum net_iov_type type;
+ unsigned long pp_magic;
+ struct page_pool *pp;
+ struct net_iov_area *owner;
+ unsigned long dma_addr;
+ atomic_long_t pp_ref_count;
+ );
};
struct net_iov_area {
@@ -73,6 +95,13 @@ NET_IOV_ASSERT_OFFSET(dma_addr, dma_addr);
NET_IOV_ASSERT_OFFSET(pp_ref_count, pp_ref_count);
#undef NET_IOV_ASSERT_OFFSET
+/*
+ * Since struct netmem_desc uses the space in struct page, the size
+ * should be checked, until struct netmem_desc has its own instance from
+ * slab, to avoid conflicting with other members within struct page.
+ */
+static_assert(sizeof(struct netmem_desc) <= offsetof(struct page, _refcount));
+
static inline struct net_iov_area *net_iov_owner(const struct net_iov *niov)
{
return niov->owner;
--
2.17.1
