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BpfMap: add ERROR_FROM_ERRNO macro helper

Browse source 
Test: TreeHugger
Flag: EXEMPT mainline, refactor, logging
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Change-Id: I496a03a2b590f0c171cb96cb4c64a430929ec3c5
This commit is contained in:
Maciej Żenczykowski 2025-08-28 11:11:03 -07:00
commit 38304c4550
1 changed files with 9 additions and 18 deletions
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27
bpf/headers/include/bpf/BpfMap.h
View file

@ -61,6 +61,7 @@ void Abort(int __unused error, const char* __unused fmt, ...) {
abort();
}
#define ERROR_FROM_ERRNO(f) ErrnoErrorf("BpfMap::" f "() failed")
// This is a class wrapper for eBPF maps. The eBPF map is a special in-kernel
// data structure that stores data in <Key, Value> pairs. It can be read/write
@ -113,25 +114,19 @@ class BpfMapRO {
Result<Key> getFirstKey() const {
Key firstKey;
if (getFirstMapKey(mMapFd, &firstKey)) {
return ErrnoErrorf("BpfMap::getFirstKey() failed");
}
if (getFirstMapKey(mMapFd, &firstKey)) return ERROR_FROM_ERRNO("getFirstKey");
return firstKey;
}
Result<Key> getNextKey(const Key& key) const {
Key nextKey;
if (getNextMapKey(mMapFd, &key, &nextKey)) {
return ErrnoErrorf("BpfMap::getNextKey() failed");
}
if (getNextMapKey(mMapFd, &key, &nextKey)) return ERROR_FROM_ERRNO("getNextKey");
return nextKey;
}
Result<Value> readValue(const Key& key) const {
Value value;
if (findMapEntry(mMapFd, &key, &value)) {
return ErrnoErrorf("BpfMap::readValue() failed");
}
if (findMapEntry(mMapFd, &key, &value)) return ERROR_FROM_ERRNO("readValue");
return value;
}
@ -184,7 +179,7 @@ class BpfMapRO {
uint32_t count = N; // how many to fetch (and possibly delete)
int rv = batchLookupAndMaybeDelete(mMapFd, first ? NULL : &batch, &batch, &keys, &values, &count, del);
if (rv && errno == ENOSPC) break; // not enough space for full HASH bucket, go around the *outer* loop
if (rv && errno != ENOENT) return ErrnoErrorf("BpfMap::doBulkLookupAndMaybeDelete() failed");
if (rv && errno != ENOENT) return ERROR_FROM_ERRNO("doBulkLookupAndMaybeDelete");
// count is now how many *were* fetched (and possibly delete)
for (unsigned i = 0; i < count; ++i) f(keys[i], values[i]);
if (rv) return {}; // ENOENT -> success
@ -329,9 +324,7 @@ class BpfMapRW : public BpfMapRO<Key, Value> {
}
Result<void> writeValue(const Key& key, const Value& value, uint64_t flags) {
if (writeToMapEntry(mMapFd, &key, &value, flags)) {
return ErrnoErrorf("BpfMap::writeValue() failed");
}
if (writeToMapEntry(mMapFd, &key, &value, flags)) return ERROR_FROM_ERRNO("writeValue");
return {};
}
@ -343,7 +336,7 @@ class BpfMapRW : public BpfMapRO<Key, Value> {
if (map_flags & BPF_F_RDONLY) Abort(0, "map_flags is read-only");
mMapFd.reset(createMap(map_type, sizeof(Key), sizeof(Value), max_entries,
map_flags));
if (!mMapFd.ok()) return ErrnoErrorf("BpfMap::resetMap() failed");
if (!mMapFd.ok()) return ERROR_FROM_ERRNO("resetMap");
abortOnMismatch(/* writable */ true);
return {};
}
@ -363,9 +356,7 @@ class BpfMap : public BpfMapRW<Key, Value> {
using BpfMapRW<Key, Value>::readValue;
Result<void> deleteValue(const Key& key) {
if (deleteMapEntry(mMapFd, &key)) {
return ErrnoErrorf("BpfMap::deleteValue() failed");
}
if (deleteMapEntry(mMapFd, &key)) return ERROR_FROM_ERRNO("deleteValue");
return {};
}
@ -373,7 +364,7 @@ class BpfMap : public BpfMapRW<Key, Value> {
if (isAtLeastKernelVersion(5, 4, 0)) {
Value value;
if (!findAndDeleteMapEntry(mMapFd, &key, &value)) return value;
if (errno == ENOENT) return ErrnoErrorf("BpfMap::readAndDeleteValue() failed");
if (errno == ENOENT) return ERROR_FROM_ERRNO("readAndDeleteValue");
};
// fallback path in case of weird error and for pre-5.4 kernels