linux-kernel - [PATCH net-next v6 1/5] mm/page_alloc: modify page_frag_alloc

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Date: Wed, 28 Feb 2024 17:30:08 +0800
From: Yunsheng Lin <linyunsheng@...wei.com>
To: <davem@...emloft.net>, <kuba@...nel.org>, <pabeni@...hat.com>
CC: <netdev@...r.kernel.org>, <linux-kernel@...r.kernel.org>, Yunsheng Lin
	<linyunsheng@...wei.com>, Alexander Duyck <alexander.duyck@...il.com>, Andrew
 Morton <akpm@...ux-foundation.org>, Eric Dumazet <edumazet@...gle.com>,
	<linux-mm@...ck.org>
Subject: [PATCH net-next v6 1/5] mm/page_alloc: modify page_frag_alloc_align() to accept align as an argument

napi_alloc_frag_align() and netdev_alloc_frag_align() accept
align as an argument, and they are thin wrappers around the
__napi_alloc_frag_align() and __netdev_alloc_frag_align() APIs
doing the alignment checking and align mask conversion, in order
to call page_frag_alloc_align() directly. The intention here is
to keep the alignment checking and the alignmask conversion in
in-line wrapper to avoid those kind of operations during execution
time since it can usually be handled during compile time.

We are going to use page_frag_alloc_align() in vhost_net.c, it
need the same kind of alignment checking and alignmask conversion,
so split up page_frag_alloc_align into an inline wrapper doing the
above operation, and add __page_frag_alloc_align() which is passed
with the align mask the original function expected as suggested by
Alexander.

Signed-off-by: Yunsheng Lin <linyunsheng@...wei.com>
CC: Alexander Duyck <alexander.duyck@...il.com>
---
 include/linux/gfp.h | 15 +++++++++++----
 mm/page_alloc.c     |  8 ++++----
 net/core/skbuff.c   |  9 ++++++---
 3 files changed, 21 insertions(+), 11 deletions(-)

diff --git a/include/linux/gfp.h b/include/linux/gfp.h
index de292a007138..28aea17fa59b 100644
--- a/include/linux/gfp.h
+++ b/include/linux/gfp.h
@@ -312,14 +312,21 @@ extern void free_pages(unsigned long addr, unsigned int order);
 
 struct page_frag_cache;
 extern void __page_frag_cache_drain(struct page *page, unsigned int count);
-extern void *page_frag_alloc_align(struct page_frag_cache *nc,
-				   unsigned int fragsz, gfp_t gfp_mask,
-				   unsigned int align_mask);
+void *__page_frag_alloc_align(struct page_frag_cache *nc, unsigned int fragsz,
+			      gfp_t gfp_mask, unsigned int align_mask);
+
+static inline void *page_frag_alloc_align(struct page_frag_cache *nc,
+					  unsigned int fragsz, gfp_t gfp_mask,
+					  unsigned int align)
+{
+	WARN_ON_ONCE(!is_power_of_2(align));
+	return __page_frag_alloc_align(nc, fragsz, gfp_mask, -align);
+}
 
 static inline void *page_frag_alloc(struct page_frag_cache *nc,
 			     unsigned int fragsz, gfp_t gfp_mask)
 {
-	return page_frag_alloc_align(nc, fragsz, gfp_mask, ~0u);
+	return __page_frag_alloc_align(nc, fragsz, gfp_mask, ~0u);
 }
 
 extern void page_frag_free(void *addr);
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 150d4f23b010..c0f7e67c4250 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -4708,9 +4708,9 @@ void __page_frag_cache_drain(struct page *page, unsigned int count)
 }
 EXPORT_SYMBOL(__page_frag_cache_drain);
 
-void *page_frag_alloc_align(struct page_frag_cache *nc,
-		      unsigned int fragsz, gfp_t gfp_mask,
-		      unsigned int align_mask)
+void *__page_frag_alloc_align(struct page_frag_cache *nc,
+			      unsigned int fragsz, gfp_t gfp_mask,
+			      unsigned int align_mask)
 {
 	unsigned int size = PAGE_SIZE;
 	struct page *page;
@@ -4779,7 +4779,7 @@ void *page_frag_alloc_align(struct page_frag_cache *nc,
 
 	return nc->va + offset;
 }
-EXPORT_SYMBOL(page_frag_alloc_align);
+EXPORT_SYMBOL(__page_frag_alloc_align);
 
 /*
  * Frees a page fragment allocated out of either a compound or order 0 page.
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 1f918e602bc4..43d7fc150acc 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -315,7 +315,8 @@ void *__napi_alloc_frag_align(unsigned int fragsz, unsigned int align_mask)
 
 	fragsz = SKB_DATA_ALIGN(fragsz);
 
-	return page_frag_alloc_align(&nc->page, fragsz, GFP_ATOMIC, align_mask);
+	return __page_frag_alloc_align(&nc->page, fragsz, GFP_ATOMIC,
+				       align_mask);
 }
 EXPORT_SYMBOL(__napi_alloc_frag_align);
 
@@ -327,13 +328,15 @@ void *__netdev_alloc_frag_align(unsigned int fragsz, unsigned int align_mask)
 	if (in_hardirq() || irqs_disabled()) {
 		struct page_frag_cache *nc = this_cpu_ptr(&netdev_alloc_cache);
 
-		data = page_frag_alloc_align(nc, fragsz, GFP_ATOMIC, align_mask);
+		data = __page_frag_alloc_align(nc, fragsz, GFP_ATOMIC,
+					       align_mask);
 	} else {
 		struct napi_alloc_cache *nc;
 
 		local_bh_disable();
 		nc = this_cpu_ptr(&napi_alloc_cache);
-		data = page_frag_alloc_align(&nc->page, fragsz, GFP_ATOMIC, align_mask);
+		data = __page_frag_alloc_align(&nc->page, fragsz, GFP_ATOMIC,
+					       align_mask);
 		local_bh_enable();
 	}
 	return data;
-- 
2.33.0