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help / color / mirror / Atom feedFrom: Tatsuo Ishii <[email protected]>
To: [email protected]
Subject: Re: Adding volatile qualifer
Date: Fri, 03 Jul 2026 20:24:23 +0900 (JST)
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>
References: <[email protected]>
> While looking into the Pgpool-II main source code, I noticed that
> local pointer array "my_backend_status" is not volatile qualified,
> while it should have been.
>
> BACKEND_STATUS *my_backend_status[MAX_NUM_BACKENDS]; /* Backend status buffer */
>
> This array members are initialized:
>
> for (i = 0; i < MAX_NUM_BACKENDS; i++)
> {
> my_backend_status[i] = &(BACKEND_INFO(i).backend_status);
> }
>
> Without volatile, *(my_backend_status[i]) could read state value
> because of compiler optimization. Since my_backend_status[i] is
> referred to in popular VALID_BACKEND macro, we should fix it in all
> supported branches.
volatile qualifier should have been attached to the right hand side
too. Attached v2 patch does it.
Regards,
--
Tatsuo Ishii
SRA OSS K.K.
English: http://www.sraoss.co.jp/index_en/
Japanese:http://www.sraoss.co.jp
Attachments:
[text/x-patch] failover_fix_v2.patch (2.1K, ../[email protected]/2-failover_fix_v2.patch)
download | inline diff:
diff --git a/src/include/pool.h b/src/include/pool.h
index 549aed30f..ef0876c84 100644
--- a/src/include/pool.h
+++ b/src/include/pool.h
@@ -345,7 +345,7 @@ extern int pool_get_major_version(void);
extern bool pool_is_node_to_be_sent_in_current_query(int node_id);
extern int pool_virtual_main_db_node_id(void);
-extern BACKEND_STATUS *my_backend_status[];
+extern volatile BACKEND_STATUS *my_backend_status[];
extern int my_main_node_id;
#define VALID_BACKEND(backend_id) \
diff --git a/src/main/pgpool_main.c b/src/main/pgpool_main.c
index 19d89cb79..14d238003 100644
--- a/src/main/pgpool_main.c
+++ b/src/main/pgpool_main.c
@@ -277,7 +277,9 @@ static pid_t pgpool_logger_pid = 0; /* pid for pgpool_logger process */
static pid_t wd_lifecheck_pid = 0; /* pid for child process handling watchdog
* lifecheck */
-BACKEND_STATUS *my_backend_status[MAX_NUM_BACKENDS]; /* Backend status buffer */
+/* Backend status buffer */
+volatile BACKEND_STATUS *my_backend_status[MAX_NUM_BACKENDS];
+
int my_main_node_id; /* Main node id buffer */
/*
@@ -3220,7 +3222,8 @@ initialize_shared_mem_objects(bool clear_memcache_oidmaps)
for (i = 0; i < MAX_NUM_BACKENDS; i++)
{
- my_backend_status[i] = &(BACKEND_INFO(i).backend_status);
+ my_backend_status[i] =
+ (volatile BACKEND_STATUS *) &(BACKEND_INFO(i).backend_status);
}
/* initialize Req_info */
@@ -3783,7 +3786,8 @@ sync_backend_from_watchdog(void)
{
BACKEND_INFO(i).backend_status = CON_DOWN;
pool_set_backend_status_changed_time(i);
- my_backend_status[i] = &(BACKEND_INFO(i).backend_status);
+ my_backend_status[i] =
+ (volatile BACKEND_STATUS *) &(BACKEND_INFO(i).backend_status);
reload_master_node_id = true;
node_status_was_changed_to_down = true;
ereport(LOG,
@@ -3802,7 +3806,8 @@ sync_backend_from_watchdog(void)
BACKEND_INFO(i).backend_status = CON_CONNECT_WAIT;
pool_set_backend_status_changed_time(i);
- my_backend_status[i] = &(BACKEND_INFO(i).backend_status);
+ my_backend_status[i] =
+ (volatile BACKEND_STATUS *) &(BACKEND_INFO(i).backend_status);
reload_master_node_id = true;
ereport(LOG,
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