From 869e78931ae6cf9039c07758d66041ec168eea8f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Deuc=D0=B5?= <shurd@sasktel.net>
Date: Thu, 18 Jan 2024 18:26:17 -0500
Subject: [PATCH] Fix rwlocks for Win32
Various bits of broken no longer broken.
---
src/xpdev/rwlockwrap.c | 29 ++++++++++++++++++++---------
1 file changed, 20 insertions(+), 9 deletions(-)
diff --git a/src/xpdev/rwlockwrap.c b/src/xpdev/rwlockwrap.c
index bc3046b196..519913599b 100644
--- a/src/xpdev/rwlockwrap.c
+++ b/src/xpdev/rwlockwrap.c
@@ -3,6 +3,7 @@
#if defined(_WIN32)
#include <stdlib.h>
+#include <stdio.h>
static struct rwlock_reader_thread *
find_self(rwlock_t *lock, struct rwlock_reader_thread ***prev)
@@ -12,7 +13,7 @@ find_self(rwlock_t *lock, struct rwlock_reader_thread ***prev)
if (prev)
*prev = &lock->rthreads;
- for (ret = NULL; ret; ret = ret->next) {
+ for (ret = lock->rthreads; ret; ret = ret->next) {
if (ret->id == self)
return ret;
if (prev) {
@@ -94,7 +95,7 @@ rwlock_tryrdlock(rwlock_t *lock)
LeaveCriticalSection(&lock->lk);
return FALSE;
}
- if (lock->writers == 0 && lock->writers_waiting == 0) {
+ if (rc->count || (lock->writers == 0 && lock->writers_waiting == 0)) {
rc->count++;
lock->readers++;
ret = TRUE;
@@ -106,23 +107,33 @@ rwlock_tryrdlock(rwlock_t *lock)
BOOL
rwlock_wrlock(rwlock_t *lock)
{
+ BOOL ret = FALSE;
EnterCriticalSection(&lock->lk);
lock->writers_waiting++;
LeaveCriticalSection(&lock->lk);
EnterCriticalSection(&lock->wlk);
EnterCriticalSection(&lock->lk);
// No recursion
- if (lock->writers == 0) {
+ while (lock->readers) {
+ LeaveCriticalSection(&lock->lk);
+ LeaveCriticalSection(&lock->wlk);
+ Sleep(1);
+ EnterCriticalSection(&lock->wlk);
+ EnterCriticalSection(&lock->lk);
+ }
+ if (lock->writers) {
+ lock->writers_waiting--;
+ ret = FALSE;
+ }
+ else {
lock->writers_waiting--;
lock->writers++;
lock->writer = GetCurrentThreadId();
- LeaveCriticalSection(&lock->lk);
- // Keep holding wlk
- return TRUE;
+ ret = TRUE;
}
LeaveCriticalSection(&lock->lk);
LeaveCriticalSection(&lock->wlk);
- return FALSE;
+ return ret;
}
BOOL
@@ -131,7 +142,7 @@ rwlock_trywrlock(rwlock_t *lock)
if (TryEnterCriticalSection(&lock->wlk)) {
EnterCriticalSection(&lock->lk);
// Prevent recursing on writer locks
- if (lock->writers == 0) {
+ if (lock->readers == 0 && lock->writers == 0) {
lock->writers++;
lock->writer = GetCurrentThreadId();
LeaveCriticalSection(&lock->lk);
@@ -163,7 +174,7 @@ rwlock_unlock(rwlock_t *lock)
return FALSE;
}
if (lock->readers) {
- rc = find_self(lock, NULL);
+ rc = find_self(lock, &prev);
if (rc && rc->count) {
rc->count--;
lock->readers--;
--
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