[Devel] [PATCH] Fix potential restart failure on uninitialized sockets

[Dan Smith]

The logic used to determine whether or not we should checkpoint or
restore a socket's buffers was not unified and thus differed in a couple
of places.  This caused a restart failure in the ipv4 code when the
checkpoint decided to write buffers of an unbound socket and ipv4 restart
didn't read them.

This adds a should-we-do-it function to checkpoint.h and makes the unified
checkpoint code use it, as well as unix and ipv4.

Signed-off-by: Dan Smith <danms at us.ibm.com>
---
 include/linux/checkpoint.h |    5 +++++
 net/checkpoint.c           |    2 +-
 net/ipv4/checkpoint.c      |    6 +++---
 net/unix/checkpoint.c      |    2 +-
 4 files changed, 10 insertions(+), 5 deletions(-)

diff --git a/include/linux/checkpoint.h b/include/linux/checkpoint.h
index a796308..d2279c1 100644
--- a/include/linux/checkpoint.h
+++ b/include/linux/checkpoint.h
@@ -38,6 +38,7 @@
 #include <linux/err.h>
 #include <linux/inetdevice.h>
 #include <net/sock.h>
+#include <net/tcp_states.h>
 
 /* sycall helpers */
 extern long do_sys_checkpoint(pid_t pid, int fd,
@@ -125,6 +126,10 @@ extern int ckpt_sock_getnames(struct ckpt_ctx *ctx,
 			      struct sockaddr *rem, unsigned *rem_len);
 extern struct sk_buff *sock_restore_skb(struct ckpt_ctx *ctx, struct sock *sk);
 extern void sock_listening_list_free(struct list_head *head);
+static inline int sock_should_do_buffers(struct sock *sk)
+{
+	return (sk->sk_state != TCP_LISTEN) && !sock_flag(sk, SOCK_DEAD);
+}
 
 #ifdef CONFIG_NETNS_CHECKPOINT
 extern int checkpoint_netns(struct ckpt_ctx *ctx, void *ptr);
diff --git a/net/checkpoint.c b/net/checkpoint.c
index b1f56bf..1a03fbc 100644
--- a/net/checkpoint.c
+++ b/net/checkpoint.c
@@ -776,7 +776,7 @@ static int __do_sock_checkpoint(struct ckpt_ctx *ctx, struct sock *sk)
 		goto out;
 
 	/* part III: socket buffers */
-	if ((sk->sk_state != TCP_LISTEN) && (!sock_flag(sk, SOCK_DEAD)))
+	if (sock_should_do_buffers(sk))
 		ret = sock_defer_write_buffers(ctx, sk);
  out:
 	ckpt_hdr_put(ctx, h);
diff --git a/net/ipv4/checkpoint.c b/net/ipv4/checkpoint.c
index bc4c998..e71e5d9 100644
--- a/net/ipv4/checkpoint.c
+++ b/net/ipv4/checkpoint.c
@@ -537,10 +537,10 @@ int inet_restore(struct ckpt_ctx *ctx,
 			 */
 			ret = sock_defer_hash(ctx, sock->sk);
 		}
-
-		if (!sock_flag(sock->sk, SOCK_DEAD))
-			ret = inet_defer_restore_buffers(ctx, sock->sk);
 	}
+
+	if (sock_should_do_buffers(sock->sk))
+		ret = inet_defer_restore_buffers(ctx, sock->sk);
  out:
 	ckpt_hdr_put(ctx, in);
 
diff --git a/net/unix/checkpoint.c b/net/unix/checkpoint.c
index c90a497..230b35d 100644
--- a/net/unix/checkpoint.c
+++ b/net/unix/checkpoint.c
@@ -443,7 +443,7 @@ static int unix_restore_connected(struct ckpt_ctx *ctx,
 		ckpt_debug("unix_defer_join: %i\n", ret);
 	}
 
-	if (!dead && !ret)
+	if (sock_should_do_buffers(sock->sk) && !ret)
 		ret = unix_defer_restore_buffers(ctx, un->this);
 
 	return ret;
-- 
1.7.1.1

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