net: allow skb_datagram_iter to be called from any context

We only use the mapping in a single context, so kmap_local is sufficient
and cheaper. Make sure to use skb_frag_foreach_page as skb frags may
contain compound pages and we need to map page by page.

Reported-by: kernel test robot <oliver.sang@intel.com>
Closes: https://lore.kernel.org/oe-lkp/202406161539.b5ff7b20-oliver.sang@intel.com
Fixes: 950fcaecd5cc ("datagram: consolidate datagram copy to iter helpers")
Signed-off-by: Sagi Grimberg <sagi@grimberg.me>
Link: https://patch.msgid.link/20240626100008.831849-1-sagi@grimberg.me
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

diff --git a/net/core/datagram.c b/net/core/datagram.c
index e614cfd8e14a50a08c764dfed30c2e0838413a93..e9ba4c7b449dbf94e990d8eba9a3659e76b4f92b 100644 (file)
--- a/net/core/datagram.c
+++ b/net/core/datagram.c
@@ -416,15 +416,22 @@ static int __skb_datagram_iter(const struct sk_buff *skb, int offset,
 
                end = start + skb_frag_size(frag);
                if ((copy = end - offset) > 0) {
-                       struct page *page = skb_frag_page(frag);
-                       u8 *vaddr = kmap(page);
+                       u32 p_off, p_len, copied;
+                       struct page *p;
+                       u8 *vaddr;
 
                        if (copy > len)
                                copy = len;
-                       n = INDIRECT_CALL_1(cb, simple_copy_to_iter,
-                                       vaddr + skb_frag_off(frag) + offset - start,
-                                       copy, data, to);
-                       kunmap(page);
+
+                       skb_frag_foreach_page(frag,
+                                             skb_frag_off(frag) + offset - start,
+                                             copy, p, p_off, p_len, copied) {
+                               vaddr = kmap_local_page(p);
+                               n = INDIRECT_CALL_1(cb, simple_copy_to_iter,
+                                       vaddr + p_off, p_len, data, to);
+                               kunmap_local(vaddr);
+                       }
+
                        offset += n;
                        if (n != copy)
                                goto short_copy;