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bpf: Clarify batch lookup/lookup_and_delete semantics

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The batch lookup and lookup_and_delete APIs have two parameters,
in_batch and out_batch, to facilitate iterative
lookup/lookup_and_deletion operations for supported maps. Except NULL
for in_batch at the start of these two batch operations, both parameters
need to point to memory equal or larger than the respective map key
size, except for various hashmaps (hash, percpu_hash, lru_hash,
lru_percpu_hash) where the in_batch/out_batch memory size should be
at least 4 bytes.

Document these semantics to clarify the API.

Signed-off-by: Martin Kelly <martin.kelly@crowdstrike.com>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20240221211838.1241578-1-martin.kelly@crowdstrike.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
This commit is contained in:
Martin Kelly
2024-02-21 13:18:38 -08:00
committed by Andrii Nakryiko
parent 16e68ab13c
commit afa81fb1cb
2 changed files with 17 additions and 6 deletions
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6
include/uapi/linux/bpf.h
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@@ -617,7 +617,11 @@ union bpf_iter_link_info {
* to NULL to begin the batched operation. After each subsequent
* **BPF_MAP_LOOKUP_BATCH**, the caller should pass the resultant
* *out_batch* as the *in_batch* for the next operation to
* continue iteration from the current point.
* continue iteration from the current point. Both *in_batch* and
* *out_batch* must point to memory large enough to hold a key,
* except for maps of type **BPF_MAP_TYPE_{HASH, PERCPU_HASH,
* LRU_HASH, LRU_PERCPU_HASH}**, for which batch parameters
* must be at least 4 bytes wide regardless of key size.
*
* The *keys* and *values* are output parameters which must point
* to memory large enough to hold *count* items based on the key