Netdev Archive on lore.kernel.org
help / color / mirror / Atom feed
From: Yunsheng Lin <linyunsheng@huawei.com>
To: <davem@davemloft.net>, <kuba@kernel.org>
Cc: <alexander.duyck@gmail.com>, <linux@armlinux.org.uk>,
	<mw@semihalf.com>, <linuxarm@openeuler.org>,
	<yisen.zhuang@huawei.com>, <salil.mehta@huawei.com>,
	<thomas.petazzoni@bootlin.com>, <hawk@kernel.org>,
	<ilias.apalodimas@linaro.org>, <ast@kernel.org>,
	<daniel@iogearbox.net>, <john.fastabend@gmail.com>,
	<akpm@linux-foundation.org>, <peterz@infradead.org>,
	<will@kernel.org>, <willy@infradead.org>, <vbabka@suse.cz>,
	<fenghua.yu@intel.com>, <guro@fb.com>, <peterx@redhat.com>,
	<feng.tang@intel.com>, <jgg@ziepe.ca>, <mcroce@microsoft.com>,
	<hughd@google.com>, <jonathan.lemon@gmail.com>, <alobakin@pm.me>,
	<willemb@google.com>, <wenxu@ucloud.cn>,
	<cong.wang@bytedance.com>, <haokexin@gmail.com>,
	<nogikh@google.com>, <elver@google.com>, <netdev@vger.kernel.org>,
	<linux-kernel@vger.kernel.org>, <bpf@vger.kernel.org>
Subject: [PATCH rfc v2 2/5] page_pool: add interface for getting and setting pagecnt_bias
Date: Sat, 10 Jul 2021 15:43:19 +0800	[thread overview]
Message-ID: <1625903002-31619-3-git-send-email-linyunsheng@huawei.com> (raw)
In-Reply-To: <1625903002-31619-1-git-send-email-linyunsheng@huawei.com>

As suggested by Alexander, "A DMA mapping should be page
aligned anyway so the lower 12 bits would be reserved 0",
so it might make more sense to repurpose the lower 12 bits
of the dma address to store the pagecnt_bias for elevated
refcnt case in page pool.

As newly added page_pool_get_pagecnt_bias() may be called
outside of the softirq context, so annotate the access to
page->dma_addr[0] with READ_ONCE() and WRITE_ONCE().

Other three interfaces using page->dma_addr[0] is only called
in the softirq context during normal rx processing, hopefully
the barrier in the rx processing will ensure the correct order
between getting and setting pagecnt_bias.

Signed-off-by: Yunsheng Lin <linyunsheng@huawei.com>
---
 include/net/page_pool.h | 24 ++++++++++++++++++++++--
 1 file changed, 22 insertions(+), 2 deletions(-)

diff --git a/include/net/page_pool.h b/include/net/page_pool.h
index 8d7744d..5746f17 100644
--- a/include/net/page_pool.h
+++ b/include/net/page_pool.h
@@ -200,7 +200,7 @@ static inline void page_pool_recycle_direct(struct page_pool *pool,
 
 static inline dma_addr_t page_pool_get_dma_addr(struct page *page)
 {
-	dma_addr_t ret = page->dma_addr[0];
+	dma_addr_t ret = READ_ONCE(page->dma_addr[0]) & PAGE_MASK;
 	if (sizeof(dma_addr_t) > sizeof(unsigned long))
 		ret |= (dma_addr_t)page->dma_addr[1] << 16 << 16;
 	return ret;
@@ -208,11 +208,31 @@ static inline dma_addr_t page_pool_get_dma_addr(struct page *page)
 
 static inline void page_pool_set_dma_addr(struct page *page, dma_addr_t addr)
 {
-	page->dma_addr[0] = addr;
+	unsigned long dma_addr_0 = READ_ONCE(page->dma_addr[0]);
+
+	dma_addr_0 &= ~PAGE_MASK;
+	dma_addr_0 |= (addr & PAGE_MASK);
+	WRITE_ONCE(page->dma_addr[0], dma_addr_0);
+
 	if (sizeof(dma_addr_t) > sizeof(unsigned long))
 		page->dma_addr[1] = upper_32_bits(addr);
 }
 
+static inline int page_pool_get_pagecnt_bias(struct page *page)
+{
+	return (READ_ONCE(page->dma_addr[0]) & ~PAGE_MASK);
+}
+
+static inline void page_pool_set_pagecnt_bias(struct page *page, int bias)
+{
+	unsigned long dma_addr_0 = READ_ONCE(page->dma_addr[0]);
+
+	dma_addr_0 &= PAGE_MASK;
+	dma_addr_0 |= (bias & ~PAGE_MASK);
+
+	WRITE_ONCE(page->dma_addr[0], dma_addr_0);
+}
+
 static inline bool is_page_pool_compiled_in(void)
 {
 #ifdef CONFIG_PAGE_POOL
-- 
2.7.4


  parent reply	other threads:[~2021-07-10  7:44 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-10  7:43 [PATCH rfc v2 0/5] add elevated refcnt support for page pool Yunsheng Lin
2021-07-10  7:43 ` [PATCH rfc v2 1/5] page_pool: keep pp info as long as page pool owns the page Yunsheng Lin
2021-07-10  7:43 ` Yunsheng Lin [this message]
2021-07-10 16:55   ` [PATCH rfc v2 2/5] page_pool: add interface for getting and setting pagecnt_bias Alexander Duyck
2021-07-12  7:44     ` Yunsheng Lin
2021-07-10  7:43 ` [PATCH rfc v2 3/5] page_pool: add page recycling support based on elevated refcnt Yunsheng Lin
2021-07-10 17:24   ` Alexander Duyck
2021-07-12  7:54     ` Yunsheng Lin
2021-07-10 17:31   ` Alexander Duyck
2021-07-12  2:06     ` Yunsheng Lin
2021-07-12  3:30       ` Alexander Duyck
2021-07-10  7:43 ` [PATCH rfc v2 4/5] page_pool: support page frag API for page pool Yunsheng Lin
2021-07-10 17:43   ` Alexander Duyck
2021-07-12  7:57     ` Yunsheng Lin
2021-07-10  7:43 ` [PATCH rfc v2 5/5] net: hns3: support skb's frag page recycling based on " Yunsheng Lin
2021-07-10 15:40 ` [PATCH rfc v2 0/5] add elevated refcnt support for " Matteo Croce

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=1625903002-31619-3-git-send-email-linyunsheng@huawei.com \
    --to=linyunsheng@huawei.com \
    --cc=akpm@linux-foundation.org \
    --cc=alexander.duyck@gmail.com \
    --cc=alobakin@pm.me \
    --cc=ast@kernel.org \
    --cc=bpf@vger.kernel.org \
    --cc=cong.wang@bytedance.com \
    --cc=daniel@iogearbox.net \
    --cc=davem@davemloft.net \
    --cc=elver@google.com \
    --cc=feng.tang@intel.com \
    --cc=fenghua.yu@intel.com \
    --cc=guro@fb.com \
    --cc=haokexin@gmail.com \
    --cc=hawk@kernel.org \
    --cc=hughd@google.com \
    --cc=ilias.apalodimas@linaro.org \
    --cc=jgg@ziepe.ca \
    --cc=john.fastabend@gmail.com \
    --cc=jonathan.lemon@gmail.com \
    --cc=kuba@kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux@armlinux.org.uk \
    --cc=linuxarm@openeuler.org \
    --cc=mcroce@microsoft.com \
    --cc=mw@semihalf.com \
    --cc=netdev@vger.kernel.org \
    --cc=nogikh@google.com \
    --cc=peterx@redhat.com \
    --cc=peterz@infradead.org \
    --cc=salil.mehta@huawei.com \
    --cc=thomas.petazzoni@bootlin.com \
    --cc=vbabka@suse.cz \
    --cc=wenxu@ucloud.cn \
    --cc=will@kernel.org \
    --cc=willemb@google.com \
    --cc=willy@infradead.org \
    --cc=yisen.zhuang@huawei.com \
    --subject='Re: [PATCH rfc v2 2/5] page_pool: add interface for getting and setting pagecnt_bias' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).