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Remove PG_MMAP_FLAGS from mem.h

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Based on name of the macro, it was implied that it could be used for all
mmap() calls on portability grounds.  However, its use is limited to
sysv_shmem.c, for CreateAnonymousSegment().  This commit removes the
declaration, reducing the confusion around it as a portability tweak,
being limited to SysV-style shared memory.

This macro has been introduced in b0fc0df936 for sysv_shmem.c,
originally.  It has been moved to mem.h in 0ac5e5a7e1 a bit later.

Suggested by: Peter Eisentraut <peter@eisentraut.org>
Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com>
Discussion: https://postgr.es/m/CAExHW5vTWABxuM5fbQcFkGuTLwaxuZDEE2vtx2WuMUWk6JnF4g@mail.gmail.com
Discussion: https://postgr.es/m/12add41a-7625-4639-a394-a5563e349322@eisentraut.org
This commit is contained in:
Michael Paquier
2026-01-26 10:52:02 +09:00
parent 83a53572a6
commit c100340729
2 changed files with 5 additions and 6 deletions
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9
src/backend/port/sysv_shmem.c
View File

@@ -602,6 +602,7 @@ CreateAnonymousSegment(Size *size)
Size allocsize = *size;
void *ptr = MAP_FAILED;
int mmap_errno = 0;
int mmap_flags = MAP_SHARED | MAP_ANONYMOUS | MAP_HASSEMAPHORE;
#ifndef MAP_HUGETLB
/* PGSharedMemoryCreate should have dealt with this case */
@@ -613,15 +614,15 @@ CreateAnonymousSegment(Size *size)
* Round up the request size to a suitable large value.
*/
Size hugepagesize;
int mmap_flags;
int huge_mmap_flags;
GetHugePageSize(&hugepagesize, &mmap_flags);
GetHugePageSize(&hugepagesize, &huge_mmap_flags);
if (allocsize % hugepagesize != 0)
allocsize = add_size(allocsize, hugepagesize - (allocsize % hugepagesize));
ptr = mmap(NULL, allocsize, PROT_READ | PROT_WRITE,
PG_MMAP_FLAGS | mmap_flags, -1, 0);
mmap_flags | huge_mmap_flags, -1, 0);
mmap_errno = errno;
if (huge_pages == HUGE_PAGES_TRY && ptr == MAP_FAILED)
elog(DEBUG1, "mmap(%zu) with MAP_HUGETLB failed, huge pages disabled: %m",
@@ -645,7 +646,7 @@ CreateAnonymousSegment(Size *size)
*/
allocsize = *size;
ptr = mmap(NULL, allocsize, PROT_READ | PROT_WRITE,
PG_MMAP_FLAGS, -1, 0);
mmap_flags, -1, 0);
mmap_errno = errno;
}

2
src/include/portability/mem.h
View File

@@ -38,8 +38,6 @@
#define MAP_NOSYNC 0
#endif
#define PG_MMAP_FLAGS (MAP_SHARED|MAP_ANONYMOUS|MAP_HASSEMAPHORE)
/* Some really old systems don't define MAP_FAILED. */
#ifndef MAP_FAILED
#define MAP_FAILED ((void *) -1)