From cfebc7080c990d60183cc486861d07db9dd8808b Mon Sep 17 00:00:00 2001 From: Alvaro Herrera Date: Fri, 7 May 2021 11:46:37 -0400 Subject: [PATCH] AlterSubscription_refresh: avoid stomping on global variable This patch replaces use of the global "wrconn" variable in AlterSubscription_refresh with a local variable of the same name, making it consistent with other functions in subscriptioncmds.c (e.g. DropSubscription). The global wrconn is only meant to be used for logical apply/tablesync worker. Abusing it this way is known to cause trouble if an apply worker manages to do a subscription refresh, such as reported by Jeremy Finzel and diagnosed by Andres Freund back in November 2020, at https://www.postgresql.org/message-id/20201111215820.qihhrz7fayu6myfi@alap3.anarazel.de Backpatch to 10. In branch master, also move the connection establishment to occur outside the PG_TRY block; this way we can remove a test for NULL in PG_FINALLY, and it also makes the code more consistent with similar code in the same file. Author: Peter Smith Reviewed-by: Bharath Rupireddy Reviewed-by: Japin Li Discussion: https://postgr.es/m/CAHut+Pu7Jv9L2BOEx_Z0UtJxfDevQSAUW2mJqWU+CtmDrEZVAg@mail.gmail.com --- src/backend/commands/subscriptioncmds.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/src/backend/commands/subscriptioncmds.c b/src/backend/commands/subscriptioncmds.c index aa88092f3a..5b02e0de0f 100644 --- a/src/backend/commands/subscriptioncmds.c +++ b/src/backend/commands/subscriptioncmds.c @@ -530,6 +530,7 @@ AlterSubscription_refresh(Subscription *sub, bool copy_data) List *subrel_states; Oid *subrel_local_oids; Oid *pubrel_local_oids; + WalReceiverConn *wrconn; ListCell *lc; int off; @@ -848,7 +849,7 @@ DropSubscription(DropSubscriptionStmt *stmt, bool isTopLevel) char originname[NAMEDATALEN]; char *err = NULL; RepOriginId originid; - WalReceiverConn *wrconn = NULL; + WalReceiverConn *wrconn; StringInfoData cmd; Form_pg_subscription form;