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Posted to cvs@httpd.apache.org by rp...@apache.org on 2019/10/11 15:11:40 UTC
svn commit: r1868296 - in /httpd/httpd/trunk: CHANGES include/ap_mmn.h
modules/proxy/mod_proxy.h modules/proxy/mod_proxy_ftp.c
modules/proxy/proxy_util.c
Author: rpluem
Date: Fri Oct 11 15:11:40 2019
New Revision: 1868296
URL: http://svn.apache.org/viewvc?rev=1868296&view=rev
Log:
Fix pool concurrency problems
Create a subpool of the connection pool for worker scoped DNS resolutions.
This is needed to avoid race conditions in using the connection pool by multiple
threads during ramp up.
Recheck after obtaining the lock if we still need to do things or if they
were already done by another thread while we were waiting on the lock.
* modules/proxy/proxy_util.c: Create a subpool of the connection pool for worker
scoped DNS resolutions and use it.
* modules/proxy/mod_proxy.h: Define AP_VOLATILIZE_T and add dns_pool to
struct proxy_conn_pool.
* modules/proxy/mod_proxy_ftp.c: Use dns_pool and consider that
worker->cp->addr is volatile in this location of the code.
PR: 63503
Modified:
httpd/httpd/trunk/CHANGES
httpd/httpd/trunk/include/ap_mmn.h
httpd/httpd/trunk/modules/proxy/mod_proxy.h
httpd/httpd/trunk/modules/proxy/mod_proxy_ftp.c
httpd/httpd/trunk/modules/proxy/proxy_util.c
Modified: httpd/httpd/trunk/CHANGES
URL: http://svn.apache.org/viewvc/httpd/httpd/trunk/CHANGES?rev=1868296&r1=1868295&r2=1868296&view=diff
==============================================================================
--- httpd/httpd/trunk/CHANGES [utf-8] (original)
+++ httpd/httpd/trunk/CHANGES [utf-8] Fri Oct 11 15:11:40 2019
@@ -1,6 +1,9 @@
-*- coding: utf-8 -*-
Changes with Apache 2.5.1
+ *) mod_proxy: Fix crash by resolving pool concurrency problems. PR 63503
+ [Ruediger Pluem, Eric Covener]
+
*) core: On Windows, fix a start-up crash if <IfFile ...> is used with a path that is not
valid (For example, testing for a file on a flash drive that is not mounted)
[Christophe Jaillet]
Modified: httpd/httpd/trunk/include/ap_mmn.h
URL: http://svn.apache.org/viewvc/httpd/httpd/trunk/include/ap_mmn.h?rev=1868296&r1=1868295&r2=1868296&view=diff
==============================================================================
--- httpd/httpd/trunk/include/ap_mmn.h (original)
+++ httpd/httpd/trunk/include/ap_mmn.h Fri Oct 11 15:11:40 2019
@@ -613,6 +613,8 @@
* 20190312.2 (2.5.1-dev) Add ap_no2slash_ex() and merge_slashes to
* core_server_conf.
* 20190312.3 (2.5.1-dev) Add forward_100_continue{,_set} to proxy_dir_conf
+ * 20190312.4 (2.5.1-dev) Add add dns_pool to proxy_conn_pool and define
+ * AP_VOLATILIZE_T.
*/
#define MODULE_MAGIC_COOKIE 0x41503235UL /* "AP25" */
@@ -620,7 +622,7 @@
#ifndef MODULE_MAGIC_NUMBER_MAJOR
#define MODULE_MAGIC_NUMBER_MAJOR 20190312
#endif
-#define MODULE_MAGIC_NUMBER_MINOR 3 /* 0...n */
+#define MODULE_MAGIC_NUMBER_MINOR 4 /* 0...n */
/**
* Determine if the server's current MODULE_MAGIC_NUMBER is at least a
Modified: httpd/httpd/trunk/modules/proxy/mod_proxy.h
URL: http://svn.apache.org/viewvc/httpd/httpd/trunk/modules/proxy/mod_proxy.h?rev=1868296&r1=1868295&r2=1868296&view=diff
==============================================================================
--- httpd/httpd/trunk/modules/proxy/mod_proxy.h (original)
+++ httpd/httpd/trunk/modules/proxy/mod_proxy.h Fri Oct 11 15:11:40 2019
@@ -287,12 +287,15 @@ typedef struct {
/* Connection pool */
struct proxy_conn_pool {
- apr_pool_t *pool; /* The pool used in constructor and destructor calls */
- apr_sockaddr_t *addr; /* Preparsed remote address info */
- apr_reslist_t *res; /* Connection resource list */
- proxy_conn_rec *conn; /* Single connection for prefork mpm */
+ apr_pool_t *pool; /* The pool used in constructor and destructor calls */
+ apr_sockaddr_t *addr; /* Preparsed remote address info */
+ apr_reslist_t *res; /* Connection resource list */
+ proxy_conn_rec *conn; /* Single connection for prefork mpm */
+ apr_pool_t *dns_pool; /* The pool used for worker scoped DNS resolutions */
};
+#define AP_VOLATILIZE_T(T, x) (*(T volatile *)&(x))
+
/* worker status bits */
/*
* NOTE: Keep up-to-date w/ proxy_wstat_tbl[]
Modified: httpd/httpd/trunk/modules/proxy/mod_proxy_ftp.c
URL: http://svn.apache.org/viewvc/httpd/httpd/trunk/modules/proxy/mod_proxy_ftp.c?rev=1868296&r1=1868295&r2=1868296&view=diff
==============================================================================
--- httpd/httpd/trunk/modules/proxy/mod_proxy_ftp.c (original)
+++ httpd/httpd/trunk/modules/proxy/mod_proxy_ftp.c Fri Oct 11 15:11:40 2019
@@ -1129,8 +1129,8 @@ static int proxy_ftp_handler(request_rec
}
#endif
}
- connect_addr = worker->cp->addr;
- address_pool = worker->cp->pool;
+ connect_addr = AP_VOLATILIZE_T(apr_sockaddr_t *, worker->cp->addr);
+ address_pool = worker->cp->dns_pool;
}
else
address_pool = r->pool;
Modified: httpd/httpd/trunk/modules/proxy/proxy_util.c
URL: http://svn.apache.org/viewvc/httpd/httpd/trunk/modules/proxy/proxy_util.c?rev=1868296&r1=1868295&r2=1868296&view=diff
==============================================================================
--- httpd/httpd/trunk/modules/proxy/proxy_util.c (original)
+++ httpd/httpd/trunk/modules/proxy/proxy_util.c Fri Oct 11 15:11:40 2019
@@ -1460,6 +1460,7 @@ static apr_status_t conn_pool_cleanup(vo
static void init_conn_pool(apr_pool_t *p, proxy_worker *worker)
{
apr_pool_t *pool;
+ apr_pool_t *dns_pool;
proxy_conn_pool *cp;
/*
@@ -1471,11 +1472,20 @@ static void init_conn_pool(apr_pool_t *p
apr_pool_create(&pool, p);
apr_pool_tag(pool, "proxy_worker_cp");
/*
+ * Create a subpool of the connection pool for worker
+ * scoped DNS resolutions. This is needed to avoid race
+ * conditions in using the connection pool by multiple
+ * threads during ramp up.
+ */
+ apr_pool_create(&dns_pool, pool);
+ apr_pool_tag(dns_pool, "proxy_worker_dns");
+ /*
* Alloc from the same pool as worker.
* proxy_conn_pool is permanently attached to the worker.
*/
cp = (proxy_conn_pool *)apr_pcalloc(p, sizeof(proxy_conn_pool));
cp->pool = pool;
+ cp->dns_pool = dns_pool;
worker->cp = cp;
}
@@ -2044,68 +2054,73 @@ PROXY_DECLARE(apr_status_t) ap_proxy_ini
ap_proxy_worker_name(p, worker));
}
else {
- ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, s, APLOGNO(00927)
- "initializing worker %s local",
- ap_proxy_worker_name(p, worker));
apr_global_mutex_lock(proxy_mutex);
- /* Now init local worker data */
+ /* Check again after we got the lock if we are still uninitialized */
+ if (!(AP_VOLATILIZE_T(unsigned int, worker->local_status) & PROXY_WORKER_INITIALIZED)) {
+ ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, s, APLOGNO(00927)
+ "initializing worker %s local",
+ ap_proxy_worker_name(p, worker));
+ /* Now init local worker data */
#if APR_HAS_THREADS
- if (worker->tmutex == NULL) {
- rv = apr_thread_mutex_create(&(worker->tmutex), APR_THREAD_MUTEX_DEFAULT, p);
- if (rv != APR_SUCCESS) {
- ap_log_error(APLOG_MARK, APLOG_ERR, rv, s, APLOGNO(00928)
- "can not create worker thread mutex");
- apr_global_mutex_unlock(proxy_mutex);
- return rv;
+ if (worker->tmutex == NULL) {
+ rv = apr_thread_mutex_create(&(worker->tmutex), APR_THREAD_MUTEX_DEFAULT, p);
+ if (rv != APR_SUCCESS) {
+ ap_log_error(APLOG_MARK, APLOG_ERR, rv, s, APLOGNO(00928)
+ "can not create worker thread mutex");
+ apr_global_mutex_unlock(proxy_mutex);
+ return rv;
+ }
}
- }
#endif
- if (worker->cp == NULL)
- init_conn_pool(p, worker);
- if (worker->cp == NULL) {
- ap_log_error(APLOG_MARK, APLOG_ERR, 0, s, APLOGNO(00929)
- "can not create connection pool");
- apr_global_mutex_unlock(proxy_mutex);
- return APR_EGENERAL;
- }
-
- if (worker->s->hmax) {
- rv = apr_reslist_create(&(worker->cp->res),
- worker->s->min, worker->s->smax,
- worker->s->hmax, worker->s->ttl,
- connection_constructor, connection_destructor,
- worker, worker->cp->pool);
-
- apr_pool_pre_cleanup_register(worker->cp->pool, worker,
- conn_pool_cleanup);
-
- ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, s, APLOGNO(00930)
- "initialized pool in child %" APR_PID_T_FMT " for (%s) min=%d max=%d smax=%d",
- getpid(), worker->s->hostname_ex, worker->s->min,
- worker->s->hmax, worker->s->smax);
-
- /* Set the acquire timeout */
- if (rv == APR_SUCCESS && worker->s->acquire_set) {
- apr_reslist_timeout_set(worker->cp->res, worker->s->acquire);
+ if (worker->cp == NULL)
+ init_conn_pool(p, worker);
+ if (worker->cp == NULL) {
+ ap_log_error(APLOG_MARK, APLOG_ERR, 0, s, APLOGNO(00929)
+ "can not create connection pool");
+ apr_global_mutex_unlock(proxy_mutex);
+ return APR_EGENERAL;
}
- }
- else {
- void *conn;
+ if (worker->s->hmax) {
+ rv = apr_reslist_create(&(worker->cp->res),
+ worker->s->min, worker->s->smax,
+ worker->s->hmax, worker->s->ttl,
+ connection_constructor, connection_destructor,
+ worker, worker->cp->pool);
+
+ apr_pool_pre_cleanup_register(worker->cp->pool, worker,
+ conn_pool_cleanup);
+
+ ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, s, APLOGNO(00930)
+ "initialized pool in child %" APR_PID_T_FMT " for (%s) min=%d max=%d smax=%d",
+ getpid(), worker->s->hostname_ex, worker->s->min,
+ worker->s->hmax, worker->s->smax);
+
+ /* Set the acquire timeout */
+ if (rv == APR_SUCCESS && worker->s->acquire_set) {
+ apr_reslist_timeout_set(worker->cp->res, worker->s->acquire);
+ }
- rv = connection_constructor(&conn, worker, worker->cp->pool);
- worker->cp->conn = conn;
+ }
+ else {
+ void *conn;
+
+ rv = connection_constructor(&conn, worker, worker->cp->pool);
+ worker->cp->conn = conn;
- ap_log_error(APLOG_MARK, APLOG_DEBUG, rv, s, APLOGNO(00931)
- "initialized single connection worker in child %" APR_PID_T_FMT " for (%s)",
- getpid(), worker->s->hostname_ex);
+ ap_log_error(APLOG_MARK, APLOG_DEBUG, rv, s, APLOGNO(00931)
+ "initialized single connection worker in child %" APR_PID_T_FMT " for (%s)",
+ getpid(), worker->s->hostname_ex);
+ }
+ if (rv == APR_SUCCESS) {
+ worker->local_status |= (PROXY_WORKER_INITIALIZED);
+ }
}
apr_global_mutex_unlock(proxy_mutex);
}
if (rv == APR_SUCCESS) {
worker->s->status |= (PROXY_WORKER_INITIALIZED);
- worker->local_status |= (PROXY_WORKER_INITIALIZED);
}
return rv;
}
@@ -2559,15 +2574,25 @@ ap_proxy_determine_connection(apr_pool_t
}
/*
- * Worker can have the single constant backend address.
- * The single DNS lookup is used once per worker.
- * If dynamic change is needed then set the addr to NULL
- * inside dynamic config to force the lookup.
+ * Recheck addr after we got the lock. This may have changed
+ * while waiting for the lock.
*/
- err = apr_sockaddr_info_get(&(worker->cp->addr),
- conn->hostname, APR_UNSPEC,
- conn->port, 0,
- worker->cp->pool);
+ if (!AP_VOLATILIZE_T(apr_sockaddr_t *, worker->cp->addr)) {
+
+ apr_sockaddr_t *addr;
+
+ /*
+ * Worker can have the single constant backend address.
+ * The single DNS lookup is used once per worker.
+ * If dynamic change is needed then set the addr to NULL
+ * inside dynamic config to force the lookup.
+ */
+ err = apr_sockaddr_info_get(&addr,
+ conn->hostname, APR_UNSPEC,
+ conn->port, 0,
+ worker->cp->dns_pool);
+ worker->cp->addr = addr;
+ }
conn->addr = worker->cp->addr;
if ((uerr = PROXY_THREAD_UNLOCK(worker)) != APR_SUCCESS) {
ap_log_rerror(APLOG_MARK, APLOG_ERR, uerr, r, APLOGNO(00946) "unlock");