Re: [PATCH v3 1/4] net: introduce helper sendpages_ok()

On 10/06/2024 13:05, Sagi Grimberg wrote:

On 06/06/2024 19:12, Ofir Gal wrote:

quoted

Network drivers are using sendpage_ok() to check the first page of an
iterator in order to disable MSG_SPLICE_PAGES. The iterator can
represent list of contiguous pages.

When MSG_SPLICE_PAGES is enabled skb_splice_from_iter() is being used,
it requires all pages in the iterator to be sendable. Therefore it needs
to check that each page is sendable.

The patch introduces a helper sendpages_ok(), it returns true if all the
contiguous pages are sendable.

Drivers who want to send contiguous pages with MSG_SPLICE_PAGES may use
this helper to check whether the page list is OK. If the helper does not
return true, the driver should remove MSG_SPLICE_PAGES flag.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Ofir Gal <redacted>
---
  include/linux/net.h | 22 ++++++++++++++++++++++
  1 file changed, 22 insertions(+)

diff --git a/include/linux/net.h b/include/linux/net.h
index 688320b79fcc..421a6b5b9ad1 100644
--- a/include/linux/net.h
+++ b/include/linux/net.h

@@ -322,6 +322,28 @@ static inline bool sendpage_ok(struct page *page)

      return !PageSlab(page) && page_count(page) >= 1;
  }
  +/*
+ * Check sendpage_ok on contiguous pages.
+ */
+static inline bool sendpages_ok(struct page *page, size_t len, size_t offset)
+{
+    struct page *p;
+    size_t count;
+
+    p = page + (offset >> PAGE_SHIFT);
+
+    count = 0;

Assignment can move to the declaration.

Applying to v4.

quoted

+    while (count < len) {
+        if (!sendpage_ok(p))
+            return false;
+
+        p++;
+        count += PAGE_SIZE;
+    }
+
+    return true;
+}
+
  int kernel_sendmsg(struct socket *sock, struct msghdr *msg, struct kvec *vec,
             size_t num, size_t len);
  int kernel_sendmsg_locked(struct sock *sk, struct msghdr *msg,

Other than that,

Reviewed-by: Sagi Grimberg <sagi@grimberg.me>

Thanks for the review.