Merge branch 'bpf-sockmap-sg-api-fixes'
Prashant Bhole says:
====================
These patches fix sg api usage in sockmap. Previously sockmap didn't
use sg_init_table(), which caused hitting BUG_ON in sg api, when
CONFIG_DEBUG_SG is enabled
v1: added sg_init_table() calls wherever needed.
v2:
- Patch1 adds new helper function in sg api. sg_init_marker()
- Patch2 sg_init_marker() and sg_init_table() in appropriate places
Backgroud:
While reviewing v1, John Fastabend raised a valid point about
unnecessary memset in sg_init_table() because sockmap uses sg table
which embedded in a struct. As enclosing struct is zeroed out, there
is unnecessary memset in sg_init_table.
So Daniel Borkmann suggested to define another static inline function
in scatterlist.h which only initializes sg_magic. Also this function
will be called from sg_init_table. From this suggestion I defined a
function sg_init_marker() which sets sg_magic and calls sg_mark_end()
====================
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
diff --git a/include/linux/scatterlist.h b/include/linux/scatterlist.h
index 22b2131..aa5d4eb 100644
--- a/include/linux/scatterlist.h
+++ b/include/linux/scatterlist.h
@@ -248,6 +248,24 @@ static inline void *sg_virt(struct scatterlist *sg)
return page_address(sg_page(sg)) + sg->offset;
}
+/**
+ * sg_init_marker - Initialize markers in sg table
+ * @sgl: The SG table
+ * @nents: Number of entries in table
+ *
+ **/
+static inline void sg_init_marker(struct scatterlist *sgl,
+ unsigned int nents)
+{
+#ifdef CONFIG_DEBUG_SG
+ unsigned int i;
+
+ for (i = 0; i < nents; i++)
+ sgl[i].sg_magic = SG_MAGIC;
+#endif
+ sg_mark_end(&sgl[nents - 1]);
+}
+
int sg_nents(struct scatterlist *sg);
int sg_nents_for_len(struct scatterlist *sg, u64 len);
struct scatterlist *sg_next(struct scatterlist *);
diff --git a/kernel/bpf/sockmap.c b/kernel/bpf/sockmap.c
index 9192fdb..d2bda5a 100644
--- a/kernel/bpf/sockmap.c
+++ b/kernel/bpf/sockmap.c
@@ -341,7 +341,7 @@ static int bpf_tcp_push(struct sock *sk, int apply_bytes,
md->sg_start++;
if (md->sg_start == MAX_SKB_FRAGS)
md->sg_start = 0;
- memset(sg, 0, sizeof(*sg));
+ sg_init_table(sg, 1);
if (md->sg_start == md->sg_end)
break;
@@ -843,7 +843,7 @@ static int bpf_tcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t size)
}
sg = md.sg_data;
- sg_init_table(sg, MAX_SKB_FRAGS);
+ sg_init_marker(sg, MAX_SKB_FRAGS);
rcu_read_unlock();
lock_sock(sk);
@@ -950,10 +950,14 @@ static int bpf_tcp_sendpage(struct sock *sk, struct page *page,
lock_sock(sk);
- if (psock->cork_bytes)
+ if (psock->cork_bytes) {
m = psock->cork;
- else
+ sg = &m->sg_data[m->sg_end];
+ } else {
m = &md;
+ sg = m->sg_data;
+ sg_init_marker(sg, MAX_SKB_FRAGS);
+ }
/* Catch case where ring is full and sendpage is stalled. */
if (unlikely(m->sg_end == m->sg_start &&
@@ -961,7 +965,6 @@ static int bpf_tcp_sendpage(struct sock *sk, struct page *page,
goto out_err;
psock->sg_size += size;
- sg = &m->sg_data[m->sg_end];
sg_set_page(sg, page, size, offset);
get_page(page);
m->sg_copy[m->sg_end] = true;
diff --git a/lib/scatterlist.c b/lib/scatterlist.c
index 53728d3..06dad7a 100644
--- a/lib/scatterlist.c
+++ b/lib/scatterlist.c
@@ -132,14 +132,7 @@ EXPORT_SYMBOL(sg_last);
void sg_init_table(struct scatterlist *sgl, unsigned int nents)
{
memset(sgl, 0, sizeof(*sgl) * nents);
-#ifdef CONFIG_DEBUG_SG
- {
- unsigned int i;
- for (i = 0; i < nents; i++)
- sgl[i].sg_magic = SG_MAGIC;
- }
-#endif
- sg_mark_end(&sgl[nents - 1]);
+ sg_init_marker(sgl, nents);
}
EXPORT_SYMBOL(sg_init_table);