Fixes skupperproject#1198: make raw connection max capacity updates a…

…tomic
kgiusti · Sep 20, 2023 · f249c0a · f249c0a
1 parent eb6e1fa
commit f249c0a
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Showing 3 changed files with 17 additions and 16 deletions.
diff --git a/src/adaptors/adaptor_common.c b/src/adaptors/adaptor_common.c
@@ -31,6 +31,7 @@
 
 #include <inttypes.h>
 #include <sys/socket.h>
+#include <stdatomic.h>
 
 ALLOC_DEFINE(qd_adaptor_config_t);
 
@@ -143,11 +144,13 @@ int qd_raw_connection_grant_read_buffers(pn_raw_connection_t *pn_raw_conn)
 
     //
     // Since we can't query Proton for the maximum read-buffer capacity, we will infer it from
-    // calls to pn_raw_connection_read_buffers_capacity.
+    // calls to pn_raw_connection_read_buffers_capacity and track the largest value returned.
     //
-    static size_t max_capacity = 0;
-    if (capacity > max_capacity) {
-        max_capacity = capacity;
+    static atomic_size_t max_capacity;  // global
+    size_t expected = atomic_load(&max_capacity);
+    while (capacity > expected) {
+        if (atomic_compare_exchange_weak(&max_capacity, &expected, capacity))
+            break;
     }
 
     //
@@ -173,9 +176,9 @@ int qd_raw_connection_grant_read_buffers(pn_raw_connection_t *pn_raw_conn)
 
     //
     // Determine how many of the desired buffers are already granted.  This will always be a
-    // non-negative value.
+    // non-negative value since max_capacity will always be > capacity
     //
-    size_t already_granted = max_capacity - capacity;
+    size_t already_granted = atomic_load(&max_capacity) - capacity;
 
     //
     // If we desire to grant additional buffers, calculate the number to grant now.

diff --git a/src/adaptors/tcp_lite/tcp_lite.c b/src/adaptors/tcp_lite/tcp_lite.c
@@ -33,6 +33,8 @@
 
 #include "tcp_lite.h"
 
+#include <stdatomic.h>
+
 //
 // Function suffixes in this module:
 //
@@ -510,9 +512,11 @@ static void grant_read_buffers_XSIDE_IO(tcplite_connection_t *conn, const size_t
     // Since we can't query Proton for the maximum read-buffer capacity, we will infer it from
     // calls to pn_raw_connection_read_buffers_capacity.
     //
-    static size_t max_capacity = 0;
-    if (capacity > max_capacity) {
-        max_capacity = capacity;
+    static atomic_size_t max_capacity;
+    size_t expected = atomic_load(&max_capacity);
+    while (capacity > expected) {
+        if (atomic_compare_exchange_weak(&max_capacity, &expected, capacity))
+            break;
     }
 
     //
@@ -539,7 +543,7 @@ static void grant_read_buffers_XSIDE_IO(tcplite_connection_t *conn, const size_t
     //
     // Determine how many buffers are already granted.  This will always be a non-negative value.
     //
-    size_t already_granted = max_capacity - capacity;
+    size_t already_granted = atomic_load(&max_capacity) - capacity;
 
     //
     // If we desire to grant additional buffers, calculate the number to grant now.

diff --git a/tests/tsan.supp b/tests/tsan.supp
@@ -76,12 +76,6 @@ race:^__lws_logv$
 # ISSUE-537 - Suppress the race in qd_entity_refresh_connector for now.
 race:^qd_entity_refresh_connector$
 
-# ISSUE-1198: Suppress warnings on race in updating max_capacity
-# https://github.com/skupperproject/skupper-router/issues/1198
-race:^qd_raw_connection_grant_read_buffers$
-race:^grant_read_buffers_XSIDE_IO$
-
-
 #
 # External libraries
 #