net: Add device Rx page allocation function
This patch implements __dev_alloc_pages and __dev_alloc_page. These are
meant to replace the __skb_alloc_pages and __skb_alloc_page functions. The
reason for doing this is that it occurred to me that __skb_alloc_page is
supposed to be passed an sk_buff pointer, but it is NULL in all cases where
it is used. Worse is that in the case of ixgbe it is passed NULL via the
sk_buff pointer in the rx_buffer info structure which means the compiler is
not correctly stripping it out.
The naming for these functions is based on dev_alloc_skb and __dev_alloc_skb.
There was originally a netdev_alloc_page, however that was passed a
net_device pointer and this function is not so I thought it best to follow
that naming scheme since that is the same difference between dev_alloc_skb
and netdev_alloc_skb.
In the case of anything greater than order 0 it is assumed that we want a
compound page so __GFP_COMP is set for all allocations as we expect a
compound page when assigning a page frag.
The other change in this patch is to exploit the behaviors of the page
allocator in how it handles flags. So for example we can always set
__GFP_COMP and __GFP_MEMALLOC since they are ignored if they are not
applicable or are overridden by another flag.
Signed-off-by: Alexander Duyck <alexander.h.duyck@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 103fbe8..2e5221f 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -2185,6 +2185,54 @@
}
/**
+ * __dev_alloc_pages - allocate page for network Rx
+ * @gfp_mask: allocation priority. Set __GFP_NOMEMALLOC if not for network Rx
+ * @order: size of the allocation
+ *
+ * Allocate a new page.
+ *
+ * %NULL is returned if there is no free memory.
+*/
+static inline struct page *__dev_alloc_pages(gfp_t gfp_mask,
+ unsigned int order)
+{
+ /* This piece of code contains several assumptions.
+ * 1. This is for device Rx, therefor a cold page is preferred.
+ * 2. The expectation is the user wants a compound page.
+ * 3. If requesting a order 0 page it will not be compound
+ * due to the check to see if order has a value in prep_new_page
+ * 4. __GFP_MEMALLOC is ignored if __GFP_NOMEMALLOC is set due to
+ * code in gfp_to_alloc_flags that should be enforcing this.
+ */
+ gfp_mask |= __GFP_COLD | __GFP_COMP | __GFP_MEMALLOC;
+
+ return alloc_pages_node(NUMA_NO_NODE, gfp_mask, order);
+}
+
+static inline struct page *dev_alloc_pages(unsigned int order)
+{
+ return __dev_alloc_pages(GFP_ATOMIC, order);
+}
+
+/**
+ * __dev_alloc_page - allocate a page for network Rx
+ * @gfp_mask: allocation priority. Set __GFP_NOMEMALLOC if not for network Rx
+ *
+ * Allocate a new page.
+ *
+ * %NULL is returned if there is no free memory.
+ */
+static inline struct page *__dev_alloc_page(gfp_t gfp_mask)
+{
+ return __dev_alloc_pages(gfp_mask, 0);
+}
+
+static inline struct page *dev_alloc_page(void)
+{
+ return __dev_alloc_page(GFP_ATOMIC);
+}
+
+/**
* __skb_alloc_pages - allocate pages for ps-rx on a skb and preserve pfmemalloc data
* @gfp_mask: alloc_pages_node mask. Set __GFP_NOMEMALLOC if not for network packet RX
* @skb: skb to set pfmemalloc on if __GFP_MEMALLOC is used