netdev - [PATCH bpf-next 03/17] bpf: Document BPF_F

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Date:   Tue, 16 Feb 2021 17:08:07 -0800
From:   Joe Stringer <joe@...d.net.nz>
To:     bpf@...r.kernel.org
Cc:     Joe Stringer <joe@...ium.io>, netdev@...r.kernel.org,
        daniel@...earbox.net, ast@...nel.org, mtk.manpages@...il.com,
        Quentin Monnet <quentin@...valent.com>
Subject: [PATCH bpf-next 03/17] bpf: Document BPF_F_LOCK in syscall commands

From: Joe Stringer <joe@...ium.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 <quentin@...valent.com>
Signed-off-by: Joe Stringer <joe@...ium.io>
---
CC: Alexei Starovoitov <ast@...nel.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