path: root/kernel/bpf/arraymap.c
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authorAlexei Starovoitov <>2014-11-13 17:36:44 -0800
committerDavid S. Miller <>2014-11-18 13:43:25 -0500
commit3274f52073d88b62f3c5ace82ae9d48546232e72 (patch)
tree372cb492d099cebc3845ad471d810a78bdaa5084 /kernel/bpf/arraymap.c
parent1bbf148ddcbafca986c0a7e66fbd518725342d0a (diff)
bpf: add 'flags' attribute to BPF_MAP_UPDATE_ELEM command
the current meaning of BPF_MAP_UPDATE_ELEM syscall command is: either update existing map element or create a new one. Initially the plan was to add a new command to handle the case of 'create new element if it didn't exist', but 'flags' style looks cleaner and overall diff is much smaller (more code reused), so add 'flags' attribute to BPF_MAP_UPDATE_ELEM command with the following meaning: #define BPF_ANY 0 /* create new element or update existing */ #define BPF_NOEXIST 1 /* create new element if it didn't exist */ #define BPF_EXIST 2 /* update existing element */ bpf_update_elem(fd, key, value, BPF_NOEXIST) call can fail with EEXIST if element already exists. bpf_update_elem(fd, key, value, BPF_EXIST) can fail with ENOENT if element doesn't exist. Userspace will call it as: int bpf_update_elem(int fd, void *key, void *value, __u64 flags) { union bpf_attr attr = { .map_fd = fd, .key = ptr_to_u64(key), .value = ptr_to_u64(value), .flags = flags; }; return bpf(BPF_MAP_UPDATE_ELEM, &attr, sizeof(attr)); } First two bits of 'flags' are used to encode style of bpf_update_elem() command. Bits 2-63 are reserved for future use. Signed-off-by: Alexei Starovoitov <> Signed-off-by: David S. Miller <>
Diffstat (limited to 'kernel/bpf/arraymap.c')
0 files changed, 0 insertions, 0 deletions