diff options
| -rw-r--r-- | src/backend/port/sysv_shmem.c | 14 | ||||
| -rw-r--r-- | src/include/port/linux.h | 13 |
2 files changed, 25 insertions, 2 deletions
diff --git a/src/backend/port/sysv_shmem.c b/src/backend/port/sysv_shmem.c index 3092ca2a377..b64f64b466f 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 - * $PostgreSQL: pgsql/src/backend/port/sysv_shmem.c,v 1.44 2005/10/15 02:49:22 momjian Exp $ + * $PostgreSQL: pgsql/src/backend/port/sysv_shmem.c,v 1.44.2.1 2007/07/02 20:12:05 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -225,6 +225,18 @@ PGSharedMemoryIsInUse(unsigned long id1, unsigned long id2) 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. diff --git a/src/include/port/linux.h b/src/include/port/linux.h index 8b137891791..6feb22e1d5c 100644 --- a/src/include/port/linux.h +++ b/src/include/port/linux.h @@ -1 +1,12 @@ - +/* + * As of July 2007, all known versions of the Linux kernel will sometimes + * return EIDRM for a shmctl() operation when EINVAL is correct (it happens + * when the low-order 15 bits of the supplied shm ID match the slot number + * assigned to a newer shmem segment). We deal with this by assuming that + * EIDRM means EINVAL in PGSharedMemoryIsInUse(). This is reasonably safe + * since in fact Linux has no excuse for ever returning EIDRM; it doesn't + * track removed segments in a way that would allow distinguishing them from + * private ones. But someday that code might get upgraded, and we'd have + * to have a kernel version test here. + */ +#define HAVE_LINUX_EIDRM_BUG |