Session cache interface redesign, Part 6:

Move mutex handling up out of the session cache providers:

* modules/ssl/ssl_private.h (modssl_sesscache_provider): Add name and 
  flags fields.  Define MODSSL_SESSCACHE_FLAG_NOTMPSAFE constant.

* modules/ssl/ssl_scache.c (ssl_scache_store, ssl_scache_retrieve,
  ssl_scache_remove, ssl_ext_status_hook): Lock and release the mutex
  around provider calls, if necessary.

* modules/ssl/ssl_engine_mutex.c (ssl_mutex_init): Do nothing if no
  session cache is configured, or the session cache does not require a
  mutex.  Otherwise, fail if no mutex is configured and the session
  cache *does* require a mutex.
  (ssl_mutex_on, ssl_mutex_off): Remove checks for mutex mode;
  functions now invoked only if necessary.

* modules/ssl/ssl_scache_dc.c, modules/ssl/ssl_scache_memcache: Set
  name and flags fields in provider structures.

* modules/ssl/ssl_scache_shmcb.c, modules/ssl_scache_dbm.c: Remove
  mutex handling through; set name and flags fields in provider
  structures; mark both as unsafe for concurrent access in flags.


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@631297 13f79535-47bb-0310-9956-ffa450edef68

1 files changed, 13 insertions, 5 deletions

diff --git a/modules/ssl/ssl_engine_mutex.c b/modules/ssl/ssl_engine_mutex.c
index bbcd92ad64..7c6145cbcd 100644
--- a/modules/ssl/ssl_engine_mutex.c
+++ b/modules/ssl/ssl_engine_mutex.c
@@ -39,12 +39,24 @@ int ssl_mutex_init(server_rec *s, apr_pool_t *p)
     SSLModConfigRec *mc = myModConfig(s);
     apr_status_t rv;
 
-    if (mc->nMutexMode == SSL_MUTEXMODE_NONE)
+    /* A mutex is only needed if a session cache is configured, and
+     * the provider used is not internally multi-process/thread
+     * safe. */
+    if (!mc->sesscache
+        || (mc->sesscache->flags & MODSSL_SESSCACHE_FLAG_NOTMPSAFE) == 0) {
         return TRUE;
+    }
 
     if (mc->pMutex) {
         return TRUE;
     }
+    else if (mc->nMutexMode == SSL_MUTEXMODE_NONE) {
+        ap_log_error(APLOG_MARK, APLOG_ERR, 0, s,
+                     "An SSLMutex is required for the '%s' session cache",
+                     mc->sesscache->name);
+        return FALSE;
+    }
+
     if ((rv = apr_global_mutex_create(&mc->pMutex, mc->szMutexFile,
                                       mc->nMutexMech, s->process->pool))
             != APR_SUCCESS) {
@@ -97,8 +109,6 @@ int ssl_mutex_on(server_rec *s)
     SSLModConfigRec *mc = myModConfig(s);
     apr_status_t rv;
 
-    if (mc->nMutexMode == SSL_MUTEXMODE_NONE)
-        return TRUE;
     if ((rv = apr_global_mutex_lock(mc->pMutex)) != APR_SUCCESS) {
         ap_log_error(APLOG_MARK, APLOG_WARNING, rv, s,
                      "Failed to acquire SSL session cache lock");
@@ -112,8 +122,6 @@ int ssl_mutex_off(server_rec *s)
     SSLModConfigRec *mc = myModConfig(s);
     apr_status_t rv;
 
-    if (mc->nMutexMode == SSL_MUTEXMODE_NONE)
-        return TRUE;
     if ((rv = apr_global_mutex_unlock(mc->pMutex)) != APR_SUCCESS) {
         ap_log_error(APLOG_MARK, APLOG_WARNING, rv, s,
                      "Failed to release SSL session cache lock");