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| author | Noah Misch <noah@leadboat.com> | 2024-11-25 14:42:35 -0800 |
|---|---|---|
| committer | Noah Misch <noah@leadboat.com> | 2024-11-25 14:42:39 -0800 |
| commit | 941e0c0df2bcdeb63bd822a1c46818fa9d7d8599 (patch) | |
| tree | cf44b7e27082f834ffd8e1b8a1a399727dc16d9c /src/backend | |
| parent | 851c6ff18fd359bebd97b7f2b73bb46981a1a8d2 (diff) | |
| download | postgresql-941e0c0df2bcdeb63bd822a1c46818fa9d7d8599.tar.gz postgresql-941e0c0df2bcdeb63bd822a1c46818fa9d7d8599.zip | |
Avoid "you don't own a lock of type ExclusiveLock" in GRANT TABLESPACE.
This WARNING appeared because SearchSysCacheLocked1() read
cc_relisshared before catcache initialization, when the field is false
unconditionally. On the basis of reading false there, it constructed a
locktag as though pg_tablespace weren't relisshared. Only shared
catalogs could be affected, and only GRANT TABLESPACE was affected in
practice. SearchSysCacheLocked1() callers use one other shared-relation
syscache, DATABASEOID. DATABASEOID is initialized by the end of
CheckMyDatabase(), making the problem unreachable for pg_database.
Back-patch to v13 (all supported versions). This has no known impact
before v16, where ExecGrant_common() first appeared. Earlier branches
avoid trouble by having a separate ExecGrant_Tablespace() that doesn't
use LOCKTAG_TUPLE. However, leaving this unfixed in v15 could ensnare a
future back-patch of a SearchSysCacheLocked1() call.
Reported by Aya Iwata.
Discussion: https://postgr.es/m/OS7PR01MB11964507B5548245A7EE54E70EA212@OS7PR01MB11964.jpnprd01.prod.outlook.com
Diffstat (limited to 'src/backend')
| -rw-r--r-- | src/backend/utils/cache/syscache.c | 15 |
1 files changed, 10 insertions, 5 deletions
diff --git a/src/backend/utils/cache/syscache.c b/src/backend/utils/cache/syscache.c index 2f619f61807..e8349a42966 100644 --- a/src/backend/utils/cache/syscache.c +++ b/src/backend/utils/cache/syscache.c @@ -1242,11 +1242,9 @@ HeapTuple SearchSysCacheLocked1(int cacheId, Datum key1) { + CatCache *cache = SysCache[cacheId]; ItemPointerData tid; LOCKTAG tag; - Oid dboid = - SysCache[cacheId]->cc_relisshared ? InvalidOid : MyDatabaseId; - Oid reloid = cacheinfo[cacheId].reloid; /*---------- * Since inplace updates may happen just before our LockTuple(), we must @@ -1298,8 +1296,15 @@ SearchSysCacheLocked1(int cacheId, tid = tuple->t_self; ReleaseSysCache(tuple); - /* like: LockTuple(rel, &tid, lockmode) */ - SET_LOCKTAG_TUPLE(tag, dboid, reloid, + + /* + * Do like LockTuple(rel, &tid, lockmode). While cc_relisshared won't + * change from one iteration to another, it may have been a temporary + * "false" until our first SearchSysCache1(). + */ + SET_LOCKTAG_TUPLE(tag, + cache->cc_relisshared ? InvalidOid : MyDatabaseId, + cache->cc_reloid, ItemPointerGetBlockNumber(&tid), ItemPointerGetOffsetNumber(&tid)); (void) LockAcquire(&tag, lockmode, false, false); |