netdev - [PATCH RFC 6/9] bpf: add a helper to find map by id

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Message-Id: <20220308131056.6732-7-laoar.shao@gmail.com>
Date:   Tue,  8 Mar 2022 13:10:53 +0000
From:   Yafang Shao <laoar.shao@...il.com>
To:     ast@...nel.org, daniel@...earbox.net, andrii@...nel.org,
        kafai@...com, songliubraving@...com, yhs@...com,
        john.fastabend@...il.com, kpsingh@...nel.org,
        akpm@...ux-foundation.org, cl@...ux.com, penberg@...nel.org,
        rientjes@...gle.com, iamjoonsoo.kim@....com, vbabka@...e.cz,
        hannes@...xchg.org, mhocko@...nel.org, vdavydov.dev@...il.com,
        guro@...com
Cc:     linux-mm@...ck.org, netdev@...r.kernel.org, bpf@...r.kernel.org,
        Yafang Shao <laoar.shao@...il.com>
Subject: [PATCH RFC 6/9] bpf: add a helper to find map by id

A new helper bpf_map_idr_find() is introduced for later use.

Signed-off-by: Yafang Shao <laoar.shao@...il.com>
---
 kernel/bpf/syscall.c | 24 ++++++++++++++++--------
 1 file changed, 16 insertions(+), 8 deletions(-)

diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 3b50fcb..68fea3b 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -3474,6 +3474,21 @@ static int bpf_prog_get_fd_by_id(const union bpf_attr *attr)
 	return fd;
 }
 
+static struct bpf_map *bpf_map_idr_find(unsigned long id)
+{
+	void *map;
+
+	spin_lock_bh(&map_idr_lock);
+	map = idr_find(&map_idr, id);
+	if (map)
+		map = __bpf_map_inc_not_zero(map, true);
+	else
+		map = ERR_PTR(-ENOENT);
+	spin_unlock_bh(&map_idr_lock);
+
+	return map;
+}
+
 #define BPF_MAP_GET_FD_BY_ID_LAST_FIELD open_flags
 
 static int bpf_map_get_fd_by_id(const union bpf_attr *attr)
@@ -3494,14 +3509,7 @@ static int bpf_map_get_fd_by_id(const union bpf_attr *attr)
 	if (f_flags < 0)
 		return f_flags;
 
-	spin_lock_bh(&map_idr_lock);
-	map = idr_find(&map_idr, id);
-	if (map)
-		map = __bpf_map_inc_not_zero(map, true);
-	else
-		map = ERR_PTR(-ENOENT);
-	spin_unlock_bh(&map_idr_lock);
-
+	map = bpf_map_idr_find(id);
 	if (IS_ERR(map))
 		return PTR_ERR(map);
 
-- 
1.8.3.1