[PATCHv2 bpf-next 03/15] bpf: Document BPF_F_LOCK in syscall commands

[Joe Stringer <joe@cilium.io>]

Document the meaning of the BPF_F_LOCK flag for the map lookup/update
descriptions. Based on commit 96049f3afd50 ("bpf: introduce BPF_F_LOCK
flag").

Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
Reviewed-by: Quentin Monnet <quentin@isovalent.com>
Signed-off-by: Joe Stringer <joe@cilium.io>
---
CC: Alexei Starovoitov <ast@kernel.org>
---
 include/uapi/linux/bpf.h | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 052bbfe65f77..eb9f059f0569 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -123,6 +123,14 @@ union bpf_iter_link_info {
  *		Look up an element with a given *key* in the map referred to
  *		by the file descriptor *map_fd*.
  *
+ *		The *flags* argument may be specified as one of the
+ *		following:
+ *
+ *		**BPF_F_LOCK**
+ *			Look up the value of a spin-locked map without
+ *			returning the lock. This must be specified if the
+ *			elements contain a spinlock.
+ *
  *	Return
  *		Returns zero on success. On error, -1 is returned and *errno*
  *		is set appropriately.
@@ -140,6 +148,8 @@ union bpf_iter_link_info {
  *			Create a new element only if it did not exist.
  *		**BPF_EXIST**
  *			Update an existing element.
+ *		**BPF_F_LOCK**
+ *			Update a spin_lock-ed map element.
  *
  *	Return
  *		Returns zero on success. On error, -1 is returned and *errno*
-- 
2.27.0