Exit correctly from PrepareRedoRemove() when not found

simonat2ndQuadrant · simonat2ndQuadrant · commit ee01f7092fb6 · 2017-04-18T11:35:38.000+01:00
Complex crash bug all started with this failure. Diagnosed and fixed by Nikhil Sontakke, reviewed by me. Reported-by: Jeff Janes Author: Nikhil Sontakke Discussion: https://postgr.es/m/CAMkU=1xBP8cqdS5eK8APHL=X6RHMMM2vG5g+QamduuTsyCwv9g@mail.gmail.com
diff --git a/src/backend/access/transam/twophase.c b/src/backend/access/transam/twophase.c
@@ -2375,6 +2375,7 @@ PrepareRedoRemove(TransactionId xid, bool giveWarning)
 {
 	GlobalTransaction gxact = NULL;
 	int			i;
+	bool		found = false;
 
 	Assert(RecoveryInProgress());
 
@@ -2386,6 +2387,7 @@ PrepareRedoRemove(TransactionId xid, bool giveWarning)
 		if (gxact->xid == xid)
 		{
 			Assert(gxact->inredo);
+			found = true;
 			break;
 		}
 	}
@@ -2394,7 +2396,7 @@ PrepareRedoRemove(TransactionId xid, bool giveWarning)
 	/*
 	 * Just leave if there is nothing, this is expected during WAL replay.
 	 */
-	if (gxact == NULL)
+	if (!found)
 		return;
 
 	/*

Original file line number	Diff line number	Diff line change
`@@ -2375,6 +2375,7 @@ PrepareRedoRemove(TransactionId xid, bool giveWarning)`
`2375`	`2375`	`{`
`2376`	`2376`	`GlobalTransaction gxact = NULL;`
`2377`	`2377`	`int i;`
	`2378`	`+ bool found = false;`
`2378`	`2379`
`2379`	`2380`	`Assert(RecoveryInProgress());`
`2380`	`2381`
`@@ -2386,6 +2387,7 @@ PrepareRedoRemove(TransactionId xid, bool giveWarning)`
`2386`	`2387`	`if (gxact->xid == xid)`
`2387`	`2388`	`{`
`2388`	`2389`	`Assert(gxact->inredo);`
	`2390`	`+ found = true;`
`2389`	`2391`	`break;`
`2390`	`2392`	`}`
`2391`	`2393`	`}`
`@@ -2394,7 +2396,7 @@ PrepareRedoRemove(TransactionId xid, bool giveWarning)`
`2394`	`2396`	`/*`
`2395`	`2397`	`* Just leave if there is nothing, this is expected during WAL replay.`
`2396`	`2398`	`*/`
`2397`		`- if (gxact == NULL)`
	`2399`	`+ if (!found)`
`2398`	`2400`	`return;`
`2399`	`2401`
`2400`	`2402`	`/*`