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Fix locking bugs that could corrupt pg_control.

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The redo routines for XLOG_CHECKPOINT_{ONLINE,SHUTDOWN} must acquire
ControlFileLock before modifying ControlFile->checkPointCopy, or the
checkpointer could write out a control file with a bad checksum.

Likewise, XLogReportParameters() must acquire ControlFileLock before
modifying ControlFile and calling UpdateControlFile().

Back-patch to all supported releases.

Author: Nathan Bossart <bossartn@amazon.com>
Author: Fujii Masao <masao.fujii@oss.nttdata.com>
Reviewed-by: Fujii Masao <masao.fujii@oss.nttdata.com>
Reviewed-by: Michael Paquier <michael@paquier.xyz>
Reviewed-by: Thomas Munro <thomas.munro@gmail.com>
Discussion: https://postgr.es/m/70BF24D6-DC51-443F-B55A-95735803842A%40amazon.com
This commit is contained in:
Thomas Munro 2020-06-08 13:57:24 +12:00
parent a1c940cc58
commit acefa2cca6
1 changed files with 8 additions and 0 deletions
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8
src/backend/access/transam/xlog.c
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@ -9743,6 +9743,8 @@ XLogReportParameters(void)
XLogFlush(recptr);
}
LWLockAcquire(ControlFileLock, LW_EXCLUSIVE);
ControlFile->MaxConnections = MaxConnections;
ControlFile->max_worker_processes = max_worker_processes;
ControlFile->max_wal_senders = max_wal_senders;
@ -9752,6 +9754,8 @@ XLogReportParameters(void)
ControlFile->wal_log_hints = wal_log_hints;
ControlFile->track_commit_timestamp = track_commit_timestamp;
UpdateControlFile();
LWLockRelease(ControlFileLock);
}
}
@ -9976,7 +9980,9 @@ xlog_redo(XLogReaderState *record)
}
/* ControlFile->checkPointCopy always tracks the latest ckpt XID */
LWLockAcquire(ControlFileLock, LW_EXCLUSIVE);
ControlFile->checkPointCopy.nextFullXid = checkPoint.nextFullXid;
LWLockRelease(ControlFileLock);
/* Update shared-memory copy of checkpoint XID/epoch */
SpinLockAcquire(&XLogCtl->info_lck);
@ -10033,7 +10039,9 @@ xlog_redo(XLogReaderState *record)
SetTransactionIdLimit(checkPoint.oldestXid,
checkPoint.oldestXidDB);
/* ControlFile->checkPointCopy always tracks the latest ckpt XID */
LWLockAcquire(ControlFileLock, LW_EXCLUSIVE);
ControlFile->checkPointCopy.nextFullXid = checkPoint.nextFullXid;
LWLockRelease(ControlFileLock);
/* Update shared-memory copy of checkpoint XID/epoch */
SpinLockAcquire(&XLogCtl->info_lck);