exp: made omfile ensure that it is not called twice in parallel on the same file instance

In theory, the rsyslog core should never call in parallel into an output
module for the same instance. However, it looks like this seems to happen
under (strange?) circumstances. I have now enhanced omfile so that it guards
itself against being called in parallel on the same instance data. This is
done to help troubleshooting and may stay as an interim solution if it
proves to solve an anomaly we see in at least one installation (to trigger
this problem, an extremely large traffic volume is needed).

1 files changed, 9 insertions, 0 deletions

diff --git a/tools/omfile.c b/tools/omfile.c
index c4e834cc..f4db7dab 100644
--- a/tools/omfile.c
+++ b/tools/omfile.c
@@ -48,6 +48,7 @@
 #include <libgen.h>
 #include <unistd.h>
 #include <sys/file.h>
+#include <pthread.h>
 
 #ifdef OS_SOLARIS
 #	include <fcntl.h>
@@ -65,6 +66,7 @@
 #include "stream.h"
 #include "unicode-helper.h"
 #include "atomic.h"
+#include "debug.h"
 
 MODULE_TYPE_OUTPUT
 
@@ -134,6 +136,7 @@ typedef struct _instanceData {
 	int	iIOBufSize;		/* size of associated io buffer */
 	int	iFlushInterval;		/* how fast flush buffer on inactivity? */
 	bool	bFlushOnTXEnd;		/* flush write buffers when transaction has ended? */
+	pthread_mutex_t mutEx;		/* guard ourselves against being called multiple times with the same instance */
 } instanceData;
 
 
@@ -603,6 +606,7 @@ finalize_it:
 BEGINcreateInstance
 CODESTARTcreateInstance
 	pData->pStrm = NULL;
+	pthread_mutex_init(&pData->mutEx, NULL);
 ENDcreateInstance
 
 
@@ -612,6 +616,7 @@ CODESTARTfreeInstance
 		dynaFileFreeCache(pData);
 	} else if(pData->pStrm != NULL)
 		strm.Destruct(&pData->pStrm);
+	pthread_mutex_destroy(&pData->mutEx);
 ENDfreeInstance
 
 
@@ -621,12 +626,14 @@ ENDtryResume
 
 BEGINdoAction
 CODESTARTdoAction
+	d_pthread_mutex_lock(&pData->mutEx);
 	DBGPRINTF("file to log to: %s\n", pData->f_fname);
 	CHKiRet(writeFile(ppString, iMsgOpts, pData));
 	if(pData->bFlushOnTXEnd) {
 		/* TODO v5: do this in endTransaction only! */
 		CHKiRet(strm.Flush(pData->pStrm));
 	}
+	d_pthread_mutex_unlock(&pData->mutEx);
 finalize_it:
 ENDdoAction
 
@@ -764,6 +771,7 @@ static rsRetVal resetConfigVariables(uchar __attribute__((unused)) *pp, void __a
 
 BEGINdoHUP
 CODESTARTdoHUP
+	d_pthread_mutex_lock(&pData->mutEx);
 	if(pData->bDynamicName) {
 		dynaFileFreeCacheEntries(pData);
 	} else {
@@ -772,6 +780,7 @@ CODESTARTdoHUP
 			pData->pStrm = NULL;
 		}
 	}
+	d_pthread_mutex_unlock(&pData->mutEx);
 ENDdoHUP