Currently net_iovs support only pp ref counts, and do not support a
page ref equivalent.
This is fine for the RX path as net_iovs are used exclusively with the
pp and only pp refcounting is needed there. The TX path however does not
use pp ref counts, thus, support for get_page/put_page equivalent is
needed for netmem.
Support get_netmem/put_netmem. Check the type of the netmem before
passing it to page or net_iov specific code to obtain a page ref
equivalent.
For dmabuf net_iovs, we obtain a ref on the underlying binding. This
ensures the entire binding doesn't disappear until all the net_iovs have
been put_netmem'ed. We do not need to track the refcount of individual
dmabuf net_iovs as we don't allocate/free them from a pool similar to
what the buddy allocator does for pages.
This code is written to be extensible by other net_iov implementers.
get_netmem/put_netmem will check the type of the netmem and route it to
the correct helper:
pages -> [get|put]_page()
dmabuf net_iovs -> net_devmem_[get|put]_net_iov()
new net_iovs -> new helpers
Signed-off-by: Mina Almasry <almasrymina@xxxxxxxxxx>
---
include/linux/skbuff_ref.h | 4 ++--
include/net/netmem.h | 3 +++
net/core/devmem.c | 10 ++++++++++
net/core/devmem.h | 11 +++++++++++
net/core/skbuff.c | 30 ++++++++++++++++++++++++++++++
5 files changed, 56 insertions(+), 2 deletions(-)
diff --git a/include/linux/skbuff_ref.h b/include/linux/skbuff_ref.h
index 0f3c58007488..9e49372ef1a0 100644
--- a/include/linux/skbuff_ref.h
+++ b/include/linux/skbuff_ref.h
@@ -17,7 +17,7 @@
*/
static inline void __skb_frag_ref(skb_frag_t *frag)
{
- get_page(skb_frag_page(frag));
+ get_netmem(skb_frag_netmem(frag));
}
/**
@@ -40,7 +40,7 @@ static inline void skb_page_unref(netmem_ref netmem, bool recycle)
if (recycle && napi_pp_put_page(netmem))
return;
#endif
- put_page(netmem_to_page(netmem));
+ put_netmem(netmem);
}
/**
diff --git a/include/net/netmem.h b/include/net/netmem.h
index 1b58faa4f20f..d30f31878a09 100644
--- a/include/net/netmem.h
+++ b/include/net/netmem.h
@@ -245,4 +245,7 @@ static inline unsigned long netmem_get_dma_addr(netmem_ref netmem)
return __netmem_clear_lsb(netmem)->dma_addr;
}
+void get_netmem(netmem_ref netmem);
+void put_netmem(netmem_ref netmem);
+
#endif /* _NET_NETMEM_H */
diff --git a/net/core/devmem.c b/net/core/devmem.c
index 0b6ed7525b22..f7e06a8cba01 100644
--- a/net/core/devmem.c
+++ b/net/core/devmem.c
@@ -322,6 +322,16 @@ void dev_dmabuf_uninstall(struct net_device *dev)
}
}
+void net_devmem_get_net_iov(struct net_iov *niov)
+{
+ net_devmem_dmabuf_binding_get(niov->owner->binding);
+}
+
+void net_devmem_put_net_iov(struct net_iov *niov)
+{
+ net_devmem_dmabuf_binding_put(niov->owner->binding);
+}
+
/*** "Dmabuf devmem memory provider" ***/
int mp_dmabuf_devmem_init(struct page_pool *pool)
diff --git a/net/core/devmem.h b/net/core/devmem.h
index 76099ef9c482..54e30fea80b3 100644
--- a/net/core/devmem.h
+++ b/net/core/devmem.h
@@ -119,6 +119,9 @@ net_devmem_dmabuf_binding_put(struct net_devmem_dmabuf_binding *binding)
__net_devmem_dmabuf_binding_free(binding);
}
+void net_devmem_get_net_iov(struct net_iov *niov);
+void net_devmem_put_net_iov(struct net_iov *niov);
+
struct net_iov *
net_devmem_alloc_dmabuf(struct net_devmem_dmabuf_binding *binding);
void net_devmem_free_dmabuf(struct net_iov *ppiov);
@@ -126,6 +129,14 @@ void net_devmem_free_dmabuf(struct net_iov *ppiov);
#else
struct net_devmem_dmabuf_binding;
+static inline void net_devmem_get_net_iov(struct net_iov *niov)
+{
+}
+
+static inline void net_devmem_put_net_iov(struct net_iov *niov)
+{
+}
+
static inline void
__net_devmem_dmabuf_binding_free(struct net_devmem_dmabuf_binding *binding)
{
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index a441613a1e6c..815245d5c36b 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -88,6 +88,7 @@
#include <linux/textsearch.h>
#include "dev.h"
+#include "devmem.h"
#include "netmem_priv.h"
#include "sock_destructor.h"
@@ -7290,3 +7291,32 @@ bool csum_and_copy_from_iter_full(void *addr, size_t bytes,
return false;
}
EXPORT_SYMBOL(csum_and_copy_from_iter_full);
+
+void get_netmem(netmem_ref netmem)
+{
+ if (netmem_is_net_iov(netmem)) {
+ /* Assume any net_iov is devmem and route it to
+ * net_devmem_get_net_iov. As new net_iov types are added they
+ * need to be checked here.
+ */
+ net_devmem_get_net_iov(netmem_to_net_iov(netmem));
+ return;
+ }
+ get_page(netmem_to_page(netmem));
+}
+EXPORT_SYMBOL(get_netmem);
+
+void put_netmem(netmem_ref netmem)
+{
+ if (netmem_is_net_iov(netmem)) {
+ /* Assume any net_iov is devmem and route it to
+ * net_devmem_put_net_iov. As new net_iov types are added they
+ * need to be checked here.
+ */
+ net_devmem_put_net_iov(netmem_to_net_iov(netmem));
+ return;
+ }
+
+ put_page(netmem_to_page(netmem));
+}
+EXPORT_SYMBOL(put_netmem);
--
2.47.1.613.gc27f4b7a9f-goog
