Fix unsafe coding in ReorderBufferCommit().

"iterstate" must be marked volatile since it's changed inside the PG_TRY
block and then used in the PG_CATCH stanza.  Noted by Mark Wilding of
Salesforce.  (We really need to see if we can't get the C compiler to warn
about this.)

Also, reset iterstate to NULL after the mainline ReorderBufferIterTXNFinish
call, to ensure the PG_CATCH block doesn't try to do that a second time.
This commit is contained in:
Tom Lane 2015-01-24 13:25:19 -05:00
parent 586dd5d6a5
commit f8a4dd2e14

View File

@ -1258,7 +1258,7 @@ ReorderBufferCommit(ReorderBuffer *rb, TransactionId xid,
TimestampTz commit_time)
{
ReorderBufferTXN *txn;
ReorderBufferIterTXNState *iterstate = NULL;
ReorderBufferIterTXNState *volatile iterstate = NULL;
ReorderBufferChange *change;
volatile CommandId command_id = FirstCommandId;
@ -1303,7 +1303,6 @@ ReorderBufferCommit(ReorderBuffer *rb, TransactionId xid,
PG_TRY();
{
/*
* Decoding needs access to syscaches et al., which in turn use
* heavyweight locks and such. Thus we need to have enough state
@ -1472,7 +1471,9 @@ ReorderBufferCommit(ReorderBuffer *rb, TransactionId xid,
}
}
/* clean up the iterator */
ReorderBufferIterTXNFinish(rb, iterstate);
iterstate = NULL;
/* call commit callback */
rb->commit(rb, txn, commit_lsn);
@ -1639,7 +1640,7 @@ ReorderBufferForget(ReorderBuffer *rb, TransactionId xid, XLogRecPtr lsn)
*/
if (txn->base_snapshot != NULL && txn->ninvalidations > 0)
{
bool use_subtxn = IsTransactionOrTransactionBlock();
bool use_subtxn = IsTransactionOrTransactionBlock();
if (use_subtxn)
BeginInternalSubTransaction("replay");