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The following commit(s) were added to refs/heads/main by this push:
new 644b4e3073 Fix volatile qualifier discard and ensure safe access to
PGPROC in lock.c
644b4e3073 is described below
commit 644b4e307380954e986f048d0a7910a3063e524e
Author: Jianghua Yang <[email protected]>
AuthorDate: Wed Feb 26 12:29:37 2025 +0800
Fix volatile qualifier discard and ensure safe access to PGPROC in lock.c
Fix https://github.com/apache/cloudberry/issues/958
---
src/backend/storage/ipc/procarray.c | 4 ++--
src/backend/storage/lmgr/lock.c | 9 +++++++--
src/include/storage/procarray.h | 2 +-
3 files changed, 10 insertions(+), 5 deletions(-)
diff --git a/src/backend/storage/ipc/procarray.c
b/src/backend/storage/ipc/procarray.c
index f16b8f4243..3154caba1b 100644
--- a/src/backend/storage/ipc/procarray.c
+++ b/src/backend/storage/ipc/procarray.c
@@ -5024,7 +5024,7 @@ DisplayXidCache(void)
}
#endif /* XIDCACHE_DEBUG */
-PGPROC *
+volatile PGPROC *
FindProcByGpSessionId(long gp_session_id)
{
/* Find the guy who should manage our locks */
@@ -5037,7 +5037,7 @@ FindProcByGpSessionId(long gp_session_id)
for (index = 0; index < arrayP->numProcs; index++)
{
- PGPROC *proc = &allProcs[arrayP->pgprocnos[index]];
+ volatile PGPROC *proc = &allProcs[arrayP->pgprocnos[index]];
if (proc->pid == MyProc->pid)
continue;
diff --git a/src/backend/storage/lmgr/lock.c b/src/backend/storage/lmgr/lock.c
index 26a52b5859..90ea0a666e 100644
--- a/src/backend/storage/lmgr/lock.c
+++ b/src/backend/storage/lmgr/lock.c
@@ -936,19 +936,24 @@ LockAcquireExtended(const LOCKTAG *locktag,
if (lockHolderProcPtr == MyProc)
{
/* Find the guy who should manage our locks */
- PGPROC * proc =
FindProcByGpSessionId(gp_session_id);
+ volatile PGPROC * proc =
FindProcByGpSessionId(gp_session_id);
int count = 0;
while(proc==NULL && count < 5)
{
pg_usleep( /* microseconds */ 2000);
count++;
CHECK_FOR_INTERRUPTS();
+ /*
+ * The reason for using
pg_memory_barrier() is to ensure that
+ * all CPU cores can see the latest
shared memory modifications.
+ */
+ pg_memory_barrier();
proc =
FindProcByGpSessionId(gp_session_id);
}
if (proc != NULL)
{
elog(DEBUG1,"Found writer proc entry.
My Pid %d, his pid %d", MyProc-> pid, proc->pid);
- lockHolderProcPtr = proc;
+ lockHolderProcPtr = (PGPROC*) proc;
}
else
ereport(FATAL,
diff --git a/src/include/storage/procarray.h b/src/include/storage/procarray.h
index cecae9371d..607834e46c 100644
--- a/src/include/storage/procarray.h
+++ b/src/include/storage/procarray.h
@@ -99,7 +99,7 @@ extern void XidCacheRemoveRunningXids(TransactionId xid,
int
nxids, const TransactionId *xids,
TransactionId latestXid);
-extern PGPROC *FindProcByGpSessionId(long gp_session_id);
+extern volatile PGPROC *FindProcByGpSessionId(long gp_session_id);
extern void UpdateCommandIdInSnapshot(CommandId curcid);
extern void updateSharedLocalSnapshot(struct DtxContextInfo *dtxContextInfo,
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