[Xen-devel] [PATCH 3/4] Add error checking in blktapctrl

[Ben Guthro <bguthro@xxxxxxxxxxxxxxx>]

[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@xxxxxxxxxxxxxxx>
Signed-off-by: Ben Guthro <bguthro@xxxxxxxxxxxxxxx>

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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