From 176bb0812fe46e117b8a185ff70abf95bb87a792 Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Tue, 9 Nov 2004 20:35:16 +0000 Subject: [PATCH] In PGSharedMemoryIsInUse, assume that EACCES indicates a shmem segment that is of no concern to us --- it must belong to a different userid, which means it is not a Postgres shmem segment (or at least, not one that is relevant to our data directory). I plan a more extensive fix in HEAD, but this is a simple change that prevents failure-to-reboot problems for single-postmaster installations. --- src/backend/port/sysv_shmem.c | 19 +++++++++++++------ 1 file changed, 13 insertions(+), 6 deletions(-) diff --git a/src/backend/port/sysv_shmem.c b/src/backend/port/sysv_shmem.c index 9ec046071c9..b44f07c8ec5 100644 --- a/src/backend/port/sysv_shmem.c +++ b/src/backend/port/sysv_shmem.c @@ -10,7 +10,7 @@ * Portions Copyright (c) 1994, Regents of the University of California * * IDENTIFICATION - * $Header: /cvsroot/pgsql/src/backend/port/sysv_shmem.c,v 1.24.2.1 2003/11/07 21:56:01 tgl Exp $ + * $Header: /cvsroot/pgsql/src/backend/port/sysv_shmem.c,v 1.24.2.2 2004/11/09 20:35:16 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -191,10 +191,6 @@ PGSharedMemoryIsInUse(unsigned long id1, unsigned long id2) /* * We detect whether a shared memory segment is in use by seeing * whether it (a) exists and (b) has any processes are attached to it. - * - * If we are unable to perform the stat operation for a reason other than - * nonexistence of the segment (most likely, because it doesn't belong - * to our userid), assume it is in use. */ if (shmctl(shmId, IPC_STAT, &shmStat) < 0) { @@ -205,7 +201,18 @@ PGSharedMemoryIsInUse(unsigned long id1, unsigned long id2) */ if (errno == EINVAL) return false; - /* Else assume segment is in use */ + /* + * EACCES implies that the segment belongs to some other userid, + * which means it is not a Postgres shmem segment (or at least, + * not one that is relevant to our data directory). + */ + if (errno == EACCES) + return false; + /* + * Otherwise, we had better assume that the segment is in use. + * The only likely case is EIDRM, which implies that the segment + * has been IPC_RMID'd but there are still processes attached to it. + */ return true; } /* If it has attached processes, it's in use */