Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next

Daniel Borkmann says:

====================
pull-request: bpf-next 2021-06-28

The following pull-request contains BPF updates for your *net-next* tree.

We've added 37 non-merge commits during the last 12 day(s) which contain
a total of 56 files changed, 394 insertions(+), 380 deletions(-).

The main changes are:

1) XDP driver RCU cleanups, from Toke Høiland-Jørgensen and Paul E. McKenney.

2) Fix bpf_skb_change_proto() IPv4/v6 GSO handling, from Maciej Żenczykowski.

3) Fix false positive kmemleak report for BPF ringbuf alloc, from Rustam Kovhaev.

4) Fix x86 JIT's extable offset calculation for PROBE_LDX NULL, from Ravi Bangoria.

5) Enable libbpf fallback probing with tracing under RHEL7, from Jonathan Edwards.

6) Clean up x86 JIT to remove unused cnt tracking from EMIT macro, from Jiri Olsa.

7) Netlink cleanups for libbpf to please Coverity, from Kumar Kartikeya Dwivedi.

8) Allow to retrieve ancestor cgroup id in tracing programs, from Namhyung Kim.

9) Fix lirc BPF program query to use user-provided prog_cnt, from Sean Young.

10) Add initial libbpf doc including generated kdoc for its API, from Grant Seltzer.

11) Make xdp_rxq_info_unreg_mem_model() more robust, from Jakub Kicinski.

12) Fix up bpfilter startup log-level to info level, from Gary Lin.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 18 insertions, 6 deletions

diff --git a/include/linux/filter.h b/include/linux/filter.h
index 688856e0b28a..472f97074da0 100644
--- a/include/linux/filter.h
+++ b/include/linux/filter.h
@@ -763,11 +763,9 @@ DECLARE_BPF_DISPATCHER(xdp)
 static __always_inline u32 bpf_prog_run_xdp(const struct bpf_prog *prog,
 					    struct xdp_buff *xdp)
 {
-	/* Caller needs to hold rcu_read_lock() (!), otherwise program
-	 * can be released while still running, or map elements could be
-	 * freed early while still having concurrent users. XDP fastpath
-	 * already takes rcu_read_lock() when fetching the program, so
-	 * it's not necessary here anymore.
+	/* Driver XDP hooks are invoked within a single NAPI poll cycle and thus
+	 * under local_bh_disable(), which provides the needed RCU protection
+	 * for accessing map entries.
 	 */
 	return __BPF_PROG_RUN(prog, xdp, BPF_DISPATCHER_FUNC(xdp));
 }
diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index 9455476c5ba2..d7895b81264e 100644
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -363,6 +363,20 @@ static inline void rcu_preempt_sleep_check(void) { }
 #define rcu_check_sparse(p, space)
 #endif /* #else #ifdef __CHECKER__ */
 
+/**
+ * unrcu_pointer - mark a pointer as not being RCU protected
+ * @p: pointer needing to lose its __rcu property
+ *
+ * Converts @p from an __rcu pointer to a __kernel pointer.
+ * This allows an __rcu pointer to be used with xchg() and friends.
+ */
+#define unrcu_pointer(p)						\
+({									\
+	typeof(*p) *_________p1 = (typeof(*p) *__force)(p);		\
+	rcu_check_sparse(p, __rcu); 					\
+	((typeof(*p) __force __kernel *)(_________p1)); 		\
+})
+
 #define __rcu_access_pointer(p, space) \
 ({ \
 	typeof(*p) *_________p1 = (typeof(*p) *__force)READ_ONCE(p); \
diff --git a/include/net/xdp_sock.h b/include/net/xdp_sock.h
index 9c0722c6d7ac..fff069d2ed1b 100644
--- a/include/net/xdp_sock.h
+++ b/include/net/xdp_sock.h
@@ -37,7 +37,7 @@ struct xdp_umem {
 struct xsk_map {
 	struct bpf_map map;
 	spinlock_t lock; /* Synchronize map updates */
-	struct xdp_sock *xsk_map[];
+	struct xdp_sock __rcu *xsk_map[];
 };
 
 struct xdp_sock {