Re: [PATCH net-next v16 05/13] page_pool: devmem support
From: Jakub Kicinski <kuba@kernel.org>
Date: 2024-07-10 16:49:03
Also in:
bpf, dri-devel, linux-alpha, linux-arch, linux-doc, linux-kselftest, linux-media, linux-mips, linux-mm, lkml, netdev, sparclinux
On Wed, 10 Jul 2024 00:17:38 +0000 Mina Almasry wrote:
quoted hunk ↗ jump to hunk
@@ -68,17 +107,103 @@ static inline netmem_ref page_to_netmem(struct page *page) static inline int netmem_ref_count(netmem_ref netmem) { + /* The non-pp refcount of net_iov is always 1. On net_iov, we only + * support pp refcounting which uses the pp_ref_count field. + */ + if (netmem_is_net_iov(netmem)) + return 1; + return page_ref_count(netmem_to_page(netmem)); }
How can this work if we had to revert the patch which made all of the networking stack take pp-aware refs? Maybe we should add the refcount, and let it be bumped, but WARN() if the net_iov is released with refcount other than 1? Or we need a very solid explanation why the conversion had to be reverted and this is fine.
static inline unsigned long netmem_to_pfn(netmem_ref netmem)
{
+ if (netmem_is_net_iov(netmem))
+ return 0;
+
return page_to_pfn(netmem_to_page(netmem));
}Can we move this out and rename it to netmem_pfn_trace() ? Silently returning 0 is not generally okay, but since it's only for tracing we don't care.
+static inline struct net_iov *__netmem_clear_lsb(netmem_ref netmem)
+{
+ return (struct net_iov *)((__force unsigned long)netmem & ~NET_IOV);
+}
+
+static inline unsigned long netmem_get_pp_magic(netmem_ref netmem)
+{
+ return __netmem_clear_lsb(netmem)->pp_magic;
+}
+
+static inline void netmem_or_pp_magic(netmem_ref netmem, unsigned long pp_magic)
+{
+ __netmem_clear_lsb(netmem)->pp_magic |= pp_magic;
+}
+
+static inline void netmem_clear_pp_magic(netmem_ref netmem)
+{
+ __netmem_clear_lsb(netmem)->pp_magic = 0;
+}
+
+static inline struct page_pool *netmem_get_pp(netmem_ref netmem)
+{
+ return __netmem_clear_lsb(netmem)->pp;
+}
+
+static inline void netmem_set_pp(netmem_ref netmem, struct page_pool *pool)
+{
+ __netmem_clear_lsb(netmem)->pp = pool;
+}Why is all this stuff in the main header? It's really low level. Please put helpers which are only used by the core in a header under net/core/, like net/core/dev.h