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Remove --disable-spinlocks.

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A later change will require atomic support, so it wouldn't make sense
for a hypothetical new system not to be able to implement spinlocks.

Reviewed-by: Heikki Linnakangas <hlinnaka@iki.fi>
Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us> (concept, not the patch)
Reviewed-by: Andres Freund <andres@anarazel.de> (concept, not the patch)
Discussion: https://postgr.es/m/3351991.1697728588%40sss.pgh.pa.us
This commit is contained in:
Thomas Munro
2024-07-30 21:45:01 +12:00
parent 1330843bb7
commit e25626677f
20 changed files with 13 additions and 486 deletions
Download Patch File Download Diff File Expand all files Collapse all files

26
src/backend/port/atomics.c
View File

@@ -57,17 +57,7 @@ pg_atomic_init_flag_impl(volatile pg_atomic_flag *ptr)
StaticAssertDecl(sizeof(ptr->sema) >= sizeof(slock_t),
"size mismatch of atomic_flag vs slock_t");
#ifndef HAVE_SPINLOCKS
/*
* NB: If we're using semaphore based TAS emulation, be careful to use a
* separate set of semaphores. Otherwise we'd get in trouble if an atomic
* var would be manipulated while spinlock is held.
*/
s_init_lock_sema((slock_t *) &ptr->sema, true);
#else
SpinLockInit((slock_t *) &ptr->sema);
#endif
ptr->value = false;
}
@@ -108,15 +98,7 @@ pg_atomic_init_u32_impl(volatile pg_atomic_uint32 *ptr, uint32 val_)
StaticAssertDecl(sizeof(ptr->sema) >= sizeof(slock_t),
"size mismatch of atomic_uint32 vs slock_t");
/*
* If we're using semaphore based atomic flags, be careful about nested
* usage of atomics while a spinlock is held.
*/
#ifndef HAVE_SPINLOCKS
s_init_lock_sema((slock_t *) &ptr->sema, true);
#else
SpinLockInit((slock_t *) &ptr->sema);
#endif
ptr->value = val_;
}
@@ -184,15 +166,7 @@ pg_atomic_init_u64_impl(volatile pg_atomic_uint64 *ptr, uint64 val_)
StaticAssertDecl(sizeof(ptr->sema) >= sizeof(slock_t),
"size mismatch of atomic_uint64 vs slock_t");
/*
* If we're using semaphore based atomic flags, be careful about nested
* usage of atomics while a spinlock is held.
*/
#ifndef HAVE_SPINLOCKS
s_init_lock_sema((slock_t *) &ptr->sema, true);
#else
SpinLockInit((slock_t *) &ptr->sema);
#endif
ptr->value = val_;
}

3
src/backend/port/posix_sema.c
View File

@@ -217,8 +217,7 @@ PGReserveSemaphores(int maxSemas)
/*
* We must use ShmemAllocUnlocked(), since the spinlock protecting
* ShmemAlloc() won't be ready yet. (This ordering is necessary when we
* are emulating spinlocks with semaphores.)
* ShmemAlloc() won't be ready yet.
*/
sharedSemas = (PGSemaphore)
ShmemAllocUnlocked(PGSemaphoreShmemSize(maxSemas));

3
src/backend/port/sysv_sema.c
View File

@@ -325,8 +325,7 @@ PGReserveSemaphores(int maxSemas)
/*
* We must use ShmemAllocUnlocked(), since the spinlock protecting
* ShmemAlloc() won't be ready yet. (This ordering is necessary when we
* are emulating spinlocks with semaphores.)
* ShmemAlloc() won't be ready yet.
*/
sharedSemas = (PGSemaphore)
ShmemAllocUnlocked(PGSemaphoreShmemSize(maxSemas));