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Arrange the bybusyness logic and prevent bad busy values

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this closes #383


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1912245 13f79535-47bb-0310-9956-ffa450edef68
This commit is contained in:
Jean-Frederic Clere
2023-09-11 13:50:21 +00:00
parent a077812a1b
commit 1b9292a4c9
4 changed files with 168 additions and 17 deletions
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119
modules/proxy/proxy_util.c
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@@ -21,6 +21,7 @@
#include "apr_version.h"
#include "apr_strings.h"
#include "apr_hash.h"
#include "apr_atomic.h"
#include "http_core.h"
#include "proxy_util.h"
#include "ajp.h"
@@ -4984,6 +4985,124 @@ PROXY_DECLARE(apr_status_t) ap_proxy_tunnel_create(proxy_tunnel_rec **ptunnel,
return APR_SUCCESS;
}
PROXY_DECLARE(apr_status_t) decrement_busy_count(void *worker_)
{
apr_size_t val;
proxy_worker *worker = worker_;
#if APR_SIZEOF_VOIDP == 4
AP_DEBUG_ASSERT(sizeof(apr_size_t) == sizeof(apr_uint32_t));
val = apr_atomic_read32(&worker->s->busy);
while (val > 0) {
apr_size_t old = val;
val = apr_atomic_cas32(&worker->s->busy, val - 1, old);
if (val == old) {
break;
}
}
#elif APR_VERSION_AT_LEAST(1,7,4) /* APR 64bit atomics not safe before 1.7.4 */
AP_DEBUG_ASSERT(sizeof(apr_size_t) == sizeof(apr_uint64_t));
val = apr_atomic_read64(&worker->s->busy);
while (val > 0) {
apr_size_t old = val;
val = apr_atomic_cas64(&worker->s->busy, val - 1, old);
if (val == old) {
break;
}
}
#else /* Use atomics for (64bit) pointers */
void *volatile *busy_p = (void *)&worker->s->busy;
AP_DEBUG_ASSERT(sizeof(apr_size_t) == sizeof(void*));
AP_DEBUG_ASSERT((apr_uintptr_t)busy_p % sizeof(void*) == 0);
val = (apr_uintptr_t)apr_atomic_casptr((void *)busy_p, NULL, NULL);
while (val > 0) {
apr_size_t old = val;
val = (apr_uintptr_t)apr_atomic_casptr((void *)busy_p,
(void *)(apr_uintptr_t)(val - 1),
(void *)(apr_uintptr_t)old);
if (val == old) {
break;
}
}
#endif
return APR_SUCCESS;
}
PROXY_DECLARE(void) increment_busy_count(proxy_worker *worker)
{
apr_size_t val;
#if APR_SIZEOF_VOIDP == 4
AP_DEBUG_ASSERT(sizeof(apr_size_t) == sizeof(apr_uint32_t));
val = apr_atomic_read32(&worker->s->busy);
while (val < APR_INT32_MAX) {
apr_size_t old = val;
val = apr_atomic_cas32(&worker->s->busy, val + 1, old);
if (val == old) {
break;
}
}
#elif APR_VERSION_AT_LEAST(1,7,4) /* APR 64bit atomics not safe before 1.7.4 */
AP_DEBUG_ASSERT(sizeof(apr_size_t) == sizeof(apr_uint64_t));
val = apr_atomic_read64(&worker->s->busy);
while (val < APR_INT64_MAX) {
apr_size_t old = val;
val = apr_atomic_cas64(&worker->s->busy, val + 1, old);
if (val == old) {
break;
}
}
#else /* Use atomics for (64bit) pointers */
void *volatile *busy_p = (void *)&worker->s->busy;
AP_DEBUG_ASSERT(sizeof(apr_size_t) == sizeof(void*));
AP_DEBUG_ASSERT((apr_uintptr_t)busy_p % sizeof(void*) == 0);
val = (apr_uintptr_t)apr_atomic_casptr((void *)busy_p, NULL, NULL);
while (val < APR_INT64_MAX) {
apr_size_t old = val;
val = (apr_uintptr_t)apr_atomic_casptr((void *)busy_p,
(void *)(apr_uintptr_t)(val + 1),
(void *)(apr_uintptr_t)old);
if (val == old) {
break;
}
}
#endif
}
PROXY_DECLARE(apr_size_t) getbusy_count(proxy_worker *worker)
{
apr_size_t val;
#if APR_SIZEOF_VOIDP == 4
AP_DEBUG_ASSERT(sizeof(apr_size_t) == sizeof(apr_uint32_t));
val = apr_atomic_read32(&worker->s->busy);
#elif APR_VERSION_AT_LEAST(1,7,4) /* APR 64bit atomics not safe before 1.7.4 */
AP_DEBUG_ASSERT(sizeof(apr_size_t) == sizeof(apr_uint64_t));
val = apr_atomic_read64(&worker->s->busy);
#else /* Use atomics for (64bit) pointers */
void *volatile *busy_p = (void *)&worker->s->busy;
AP_DEBUG_ASSERT(sizeof(apr_size_t) == sizeof(void*));
AP_DEBUG_ASSERT((apr_uintptr_t)busy_p % sizeof(void*) == 0);
val = (apr_uintptr_t)apr_atomic_casptr((void *)busy_p, NULL, NULL);
#endif
return val;
}
PROXY_DECLARE(void) setbusy_count(proxy_worker *worker, apr_size_t to)
{
#if APR_SIZEOF_VOIDP == 4
AP_DEBUG_ASSERT(sizeof(apr_size_t) == sizeof(apr_uint32_t));
apr_atomic_set32(&worker->s->busy, to);
#elif APR_VERSION_AT_LEAST(1,7,4) /* APR 64bit atomics not safe before 1.7.4 */
AP_DEBUG_ASSERT(sizeof(apr_size_t) == sizeof(apr_uint64_t));
apr_atomic_set64(&worker->s->busy, to);
#else /* Use atomics for (64bit) pointers */
void *volatile *busy_p = (void *)&worker->s->busy;
AP_DEBUG_ASSERT(sizeof(apr_size_t) == sizeof(void*));
AP_DEBUG_ASSERT((apr_uintptr_t)busy_p % sizeof(void*) == 0);
apr_atomic_xchgptr((void *)busy_p, (void *)(apr_uintptr_t)to);
#endif
}
static void add_pollset(apr_pollset_t *pollset, apr_pollfd_t *pfd,
apr_int16_t events)
{