diff options
Diffstat (limited to 'src/backend/port/sysv_shmem.c')
| -rw-r--r-- | src/backend/port/sysv_shmem.c | 30 |
1 files changed, 24 insertions, 6 deletions
diff --git a/src/backend/port/sysv_shmem.c b/src/backend/port/sysv_shmem.c index 94e285ff2b1..8834c08bbec 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 1.4.2.1 2003/11/30 21:56:36 tgl Exp $ + * $Header: /cvsroot/pgsql/src/backend/port/sysv_shmem.c,v 1.4.2.2 2007/07/02 20:12:26 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -219,10 +219,6 @@ 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) { @@ -233,7 +229,29 @@ 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; + /* + * Some Linux kernel versions (in fact, all of them as of July 2007) + * sometimes return EIDRM when EINVAL is correct. The Linux kernel + * actually does not have any internal state that would justify + * returning EIDRM, so we can get away with assuming that EIDRM is + * equivalent to EINVAL on that platform. + */ +#ifdef HAVE_LINUX_EIDRM_BUG + if (errno == EIDRM) + return false; +#endif + /* + * 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 */ |