From mboxrd@z Thu Jan  1 00:00:00 1970
From: Ben Guthro <bguthro@virtualiron.com>
Subject: [PATCH 3/4] Add error checking in blktapctrl
Date: Tue, 19 Jun 2007 09:16:35 -0400
Message-ID: <4677D733.8090604@virtualiron.com>
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[PATCH 3/4] Add error checking in blktapctrl
blktap-fixes.patch
Add some additional error checking to blktapctrl during mkfifo
Signed-off-by: Boris Ostrovsky <bostrovsky@virtualiron.com>
Signed-off-by: Ben Guthro <bguthro@virtualiron.com>

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diff -r 46e334d40a68 tools/blktap/drivers/blktapctrl.c
--- a/tools/blktap/drivers/blktapctrl.c	Mon Jun 04 14:24:51 2007 -0400
+++ b/tools/blktap/drivers/blktapctrl.c	Mon Jun 04 14:24:56 2007 -0400
@@ -604,11 +604,28 @@ int open_ctrl_socket(char *devname)
 	if (mkdir(BLKTAP_CTRL_DIR, 0755) == 0)
 		DPRINTF("Created %s directory\n", BLKTAP_CTRL_DIR);
 	ret = mkfifo(devname,S_IRWXU|S_IRWXG|S_IRWXO);
-	if ( (ret != 0) && (errno != EEXIST) ) {
-		DPRINTF("ERROR: pipe failed (%d)\n", errno);
-		exit(0);
-	}
-
+	if (ret) {
+		if (errno == EEXIST) {
+			/* 
+			 * Remove fifo since it may have data from
+			 * it's previous use --- earlier invocation 
+			 * of tapdisk may not have read all messages.
+			 */
+			ret = unlink(devname);
+			if (ret) {
+				DPRINTF("ERROR: unlink(%s) failed (%d)\n", 
+					devname, errno);
+				exit(0);
+			}
+
+			ret = mkfifo(devname,S_IRWXU|S_IRWXG|S_IRWXO);
+		}
+		if (ret) {
+			DPRINTF("ERROR: pipe failed (%d)\n", errno);
+			exit(0);
+		}
+	}
+	
 	ipc_fd = open(devname,O_RDWR|O_NONBLOCK);
 
 	if (ipc_fd < 0) {


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