bpf: follow idr code convention

Generally we do a preload before doing idr allocation. This also help
improve the allocation success rate in memory pressure.

Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Shaohua Li <shli@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index dd172ee16716a6ba0e05dbaa8e8e907273d53133..77d45bd9f5072403b471e136e28e4c8e65b0417c 100644 (file)
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -203,11 +203,13 @@ static int bpf_map_alloc_id(struct bpf_map *map)
 {
        int id;
 
+       idr_preload(GFP_KERNEL);
        spin_lock_bh(&map_idr_lock);
        id = idr_alloc_cyclic(&map_idr, map, 1, INT_MAX, GFP_ATOMIC);
        if (id > 0)
                map->id = id;
        spin_unlock_bh(&map_idr_lock);
+       idr_preload_end();
 
        if (WARN_ON_ONCE(!id))
                return -ENOSPC;
@@ -940,11 +942,13 @@ static int bpf_prog_alloc_id(struct bpf_prog *prog)
 {
        int id;
 
+       idr_preload(GFP_KERNEL);
        spin_lock_bh(&prog_idr_lock);
        id = idr_alloc_cyclic(&prog_idr, prog, 1, INT_MAX, GFP_ATOMIC);
        if (id > 0)
                prog->aux->id = id;
        spin_unlock_bh(&prog_idr_lock);
+       idr_preload_end();
 
        /* id is in [1, INT_MAX) */
        if (WARN_ON_ONCE(!id))