From: Joe Stringer <j...@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").

Reviewed-by: Quentin Monnet <quen...@isovalent.com>
Signed-off-by: Joe Stringer <j...@cilium.io>
---
CC: Alexei Starovoitov <a...@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 ac6880d7b01b..d02259458fd6 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -120,6 +120,14 @@ 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.
@@ -137,6 +145,8 @@ 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

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