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Revert "ck_rwlock: Migrate to 32-bit primitives and add a write_latch operation."

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This reverts commit 210b724061.

Conflicts:
	include/ck_rwlock.h
ck_pring
Samy Al Bahra 11 years ago
parent 6ccfb84d81
commit e2913ab9c0
1 changed files with 32 additions and 54 deletions
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86
include/ck_rwlock.h
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@ -29,18 +29,16 @@
#include <ck_elide.h>
#include <ck_pr.h>
#include <ck_stdint.h>
#include <stdbool.h>
#include <stddef.h>
struct ck_rwlock {
uint32_t writer;
uint32_t n_readers;
unsigned int writer;
unsigned int n_readers;
};
typedef struct ck_rwlock ck_rwlock_t;
#define CK_RWLOCK_INITIALIZER {0, 0}
#define CK_RWLOCK_LATCH_SHIFT 16
CK_CC_INLINE static void
ck_rwlock_init(struct ck_rwlock *rw)
@ -57,7 +55,7 @@ ck_rwlock_write_unlock(ck_rwlock_t *rw)
{
ck_pr_fence_release();
ck_pr_store_32(&rw->writer, 0);
ck_pr_store_uint(&rw->writer, 0);
return;
}
@ -66,14 +64,14 @@ ck_rwlock_locked_writer(ck_rwlock_t *rw)
{
ck_pr_fence_load();
return ck_pr_load_32(&rw->writer);
return ck_pr_load_uint(&rw->writer);
}
CK_CC_INLINE static void
ck_rwlock_write_downgrade(ck_rwlock_t *rw)
{
ck_pr_inc_32(&rw->n_readers);
ck_pr_inc_uint(&rw->n_readers);
ck_rwlock_write_unlock(rw);
return;
}
@ -84,22 +82,22 @@ ck_rwlock_locked(ck_rwlock_t *rw)
unsigned int r;
ck_pr_fence_load();
r = ck_pr_load_32(&rw->writer);
r = ck_pr_load_uint(&rw->writer);
ck_pr_fence_load();
return ck_pr_load_32(&rw->n_readers) | r;
return ck_pr_load_uint(&rw->n_readers) | r;
}
CK_CC_INLINE static bool
ck_rwlock_write_trylock(ck_rwlock_t *rw)
{
if (ck_pr_fas_32(&rw->writer, 1) != 0)
if (ck_pr_fas_uint(&rw->writer, 1) != 0)
return false;
ck_pr_fence_atomic_load();
if (ck_pr_load_32(&rw->n_readers) != 0) {
if (ck_pr_load_uint(&rw->n_readers) != 0) {
ck_rwlock_write_unlock(rw);
return false;
}
@ -110,38 +108,16 @@ ck_rwlock_write_trylock(ck_rwlock_t *rw)
CK_ELIDE_TRYLOCK_PROTOTYPE(ck_rwlock_write, ck_rwlock_t,
ck_rwlock_locked, ck_rwlock_write_trylock)
CK_CC_INLINE static void
ck_rwlock_write_latch(ck_rwlock_t *rw)
{
uint32_t snapshot = ck_pr_load_uint(&rw->n_readers);
uint32_t delta = snapshot + (1UL << CK_RWLOCK_LATCH_SHIFT);
while (ck_pr_cas_32_value(&rw->n_readers, snapshot, delta, &snapshot) == false) {
delta = snapshot + (1UL << CK_RWLOCK_LATCH_SHIFT);
ck_pr_stall();
}
return;
}
CK_CC_INLINE static void
ck_rwlock_write_unlatch(ck_rwlock_t *rw)
{
ck_pr_add_32(&rw->n_readers, 1UL << CK_RWLOCK_LATCH_SHIFT);
return;
}
CK_CC_INLINE static void
ck_rwlock_write_lock(ck_rwlock_t *rw)
{
while (ck_pr_fas_32(&rw->writer, 1) != 0)
while (ck_pr_fas_uint(&rw->writer, 1) != 0)
ck_pr_stall();
ck_pr_fence_atomic_load();
while (ck_pr_load_32(&rw->n_readers) != 0)
while (ck_pr_load_uint(&rw->n_readers) != 0)
ck_pr_stall();
return;
@ -155,10 +131,10 @@ CK_CC_INLINE static bool
ck_rwlock_read_trylock(ck_rwlock_t *rw)
{
if (ck_pr_load_32(&rw->writer) != 0)
if (ck_pr_load_uint(&rw->writer) != 0)
return false;
ck_pr_inc_32(&rw->n_readers);
ck_pr_inc_uint(&rw->n_readers);
/*
* Serialize with respect to concurrent write
@ -166,12 +142,12 @@ ck_rwlock_read_trylock(ck_rwlock_t *rw)
*/
ck_pr_fence_atomic_load();
if (ck_pr_load_32(&rw->writer) == 0) {
if (ck_pr_load_uint(&rw->writer) == 0) {
ck_pr_fence_load();
return true;
}
ck_pr_dec_32(&rw->n_readers);
ck_pr_dec_uint(&rw->n_readers);
return false;
}
@ -181,12 +157,12 @@ CK_ELIDE_TRYLOCK_PROTOTYPE(ck_rwlock_read, ck_rwlock_t,
CK_CC_INLINE static void
ck_rwlock_read_lock(ck_rwlock_t *rw)
{
uint32_t snapshot;
for (;;) {
while (ck_pr_load_32(&rw->writer) != 0)
while (ck_pr_load_uint(&rw->writer) != 0)
ck_pr_stall();
<<<<<<< HEAD
snapshot = ck_pr_faa_32(&rw->n_readers, 1);
if (snapshot >> CK_RWLOCK_LATCH_SHIFT) {
do {
@ -197,6 +173,9 @@ ck_rwlock_read_lock(ck_rwlock_t *rw)
ck_pr_cas_32(&rw->n_readers, snapshot + 1, snapshot);
continue;
}
=======
ck_pr_inc_uint(&rw->n_readers);
>>>>>>> parent of 210b724... ck_rwlock: Migrate to 32-bit primitives and add a write_latch operation.
/*
* Serialize with respect to concurrent write
@ -204,10 +183,10 @@ ck_rwlock_read_lock(ck_rwlock_t *rw)
*/
ck_pr_fence_atomic_load();
if (ck_pr_load_32(&rw->writer) == 0)
if (ck_pr_load_uint(&rw->writer) == 0)
break;
ck_pr_dec_32(&rw->n_readers);
ck_pr_dec_uint(&rw->n_readers);
}
/* Acquire semantics are necessary. */
@ -220,7 +199,7 @@ ck_rwlock_locked_reader(ck_rwlock_t *rw)
{
ck_pr_fence_load();
return ck_pr_load_32(&rw->n_readers);
return ck_pr_load_uint(&rw->n_readers);
}
CK_CC_INLINE static void
@ -228,7 +207,7 @@ ck_rwlock_read_unlock(ck_rwlock_t *rw)
{
ck_pr_fence_load_atomic();
ck_pr_dec_32(&rw->n_readers);
ck_pr_dec_uint(&rw->n_readers);
return;
}
@ -252,16 +231,16 @@ ck_rwlock_recursive_write_lock(ck_rwlock_recursive_t *rw, unsigned int tid)
{
unsigned int o;
o = ck_pr_load_32(&rw->rw.writer);
o = ck_pr_load_uint(&rw->rw.writer);
if (o == tid)
goto leave;
while (ck_pr_cas_32(&rw->rw.writer, 0, tid) == false)
while (ck_pr_cas_uint(&rw->rw.writer, 0, tid) == false)
ck_pr_stall();
ck_pr_fence_atomic_load();
while (ck_pr_load_32(&rw->rw.n_readers) != 0)
while (ck_pr_load_uint(&rw->rw.n_readers) != 0)
ck_pr_stall();
leave:
@ -274,17 +253,17 @@ ck_rwlock_recursive_write_trylock(ck_rwlock_recursive_t *rw, unsigned int tid)
{
unsigned int o;
o = ck_pr_load_32(&rw->rw.writer);
o = ck_pr_load_uint(&rw->rw.writer);
if (o == tid)
goto leave;
if (ck_pr_cas_32(&rw->rw.writer, 0, tid) == false)
if (ck_pr_cas_uint(&rw->rw.writer, 0, tid) == false)
return false;
ck_pr_fence_atomic_load();
if (ck_pr_load_32(&rw->rw.n_readers) != 0) {
ck_pr_store_32(&rw->rw.writer, 0);
if (ck_pr_load_uint(&rw->rw.n_readers) != 0) {
ck_pr_store_uint(&rw->rw.writer, 0);
return false;
}
@ -299,7 +278,7 @@ ck_rwlock_recursive_write_unlock(ck_rwlock_recursive_t *rw)
if (--rw->wc == 0) {
ck_pr_fence_release();
ck_pr_store_32(&rw->rw.writer, 0);
ck_pr_store_uint(&rw->rw.writer, 0);
}
return;
@ -328,6 +307,5 @@ ck_rwlock_recursive_read_unlock(ck_rwlock_recursive_t *rw)
return;
}
#undef CK_RWLOCK_LATCH_SHIFT
#endif /* _CK_RWLOCK_H */

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