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authorTom Lane <tgl@sss.pgh.pa.us>2004-11-09 20:35:16 +0000
committerTom Lane <tgl@sss.pgh.pa.us>2004-11-09 20:35:16 +0000
commit176bb0812fe46e117b8a185ff70abf95bb87a792 (patch)
treea6aba9eae1b379def336d0204e855a5d2a892a47 /src
parent3392959b6ee9574ff3928715ab204a3210eb4e67 (diff)
downloadpostgresql-176bb0812fe46e117b8a185ff70abf95bb87a792.tar.gz
postgresql-176bb0812fe46e117b8a185ff70abf95bb87a792.zip
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.
Diffstat (limited to 'src')
-rw-r--r--src/backend/port/sysv_shmem.c19
1 files 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 */