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In PGSharedMemoryIsInUse, assume that EACCES indicates a shmem segment

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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.
This commit is contained in:
Tom Lane 2004-11-09 20:35:16 +00:00
parent 3392959b6e
commit 176bb0812f
1 changed files with 13 additions and 6 deletions
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19
src/backend/port/sysv_shmem.c
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@ -10,7 +10,7 @@
* Portions Copyright (c) 1994, Regents of the University of California * Portions Copyright (c) 1994, Regents of the University of California
* *
* IDENTIFICATION * 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 * 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. * 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) if (shmctl(shmId, IPC_STAT, &shmStat) < 0)
{ {
@ -205,7 +201,18 @@ PGSharedMemoryIsInUse(unsigned long id1, unsigned long id2)
*/ */
if (errno == EINVAL) if (errno == EINVAL)
return false; 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; return true;
} }
/* If it has attached processes, it's in use */ /* If it has attached processes, it's in use */