[PATCH] handling errors in blktaplib

[aq <aquynh@gmail.com>]

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blktaplib doesnt handle errors properly in several places: it just
printed out the error message and exit, which is a bad behaviour for a
library.

this patch (against ChangeSet@1.1712) fixes the problem and then
handles the potential errors in blkdump. it also makes few cleanups.
(Andrew, there is another fix for parallax, but it will be sent later,
after  my last patch on parallax get merged/rejected)

Signed-off-by: Nguyen Anh Quynh <aquynh@gmail.com>


$ diffstat blktap2.patch 
 blkdump.c   |   18 +++++++++++++++---
 blktaplib.c |   46 +++++++++++++++++++++++++++++++---------------
 blktaplib.h |   12 +++++++++---
 3 files changed, 55 insertions(+), 21 deletions(-)

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===== tools/blktap/blkdump.c 1.3 vs edited =====
--- 1.3/tools/blktap/blkdump.c	2005-05-20 23:49:32 +09:00
+++ edited/tools/blktap/blkdump.c	2005-06-13 16:58:33 +09:00
@@ -122,9 +122,21 @@
 
 int main(int argc, char *argv[])
 {
-    blktap_register_ctrl_hook("control_print", control_print);
-    blktap_register_request_hook("request_print", request_print);
-    blktap_register_response_hook("response_print", response_print);
+    if (blktap_register_ctrl_hook("control_print", control_print) == -1)
+    {
+        printf("Error on registering control_print hook. Halt!\n");
+        return -1;
+    }
+    if (blktap_register_request_hook("request_print", request_print) == -1)
+    {
+        printf("Error on registering request_print hook. Halt!\n");
+        return -1;
+    }
+    if (blktap_register_response_hook("response_print", response_print) == -1)
+    {
+        printf("Error on registering response_print hook. Halt!\n");
+        return -1;
+    }
     blktap_listen();
     
     return 0;
===== tools/blktap/blktaplib.c 1.6 vs edited =====
--- 1.6/tools/blktap/blktaplib.c	2005-06-04 23:00:20 +09:00
+++ edited/tools/blktap/blktaplib.c	2005-06-13 16:48:30 +09:00
@@ -110,12 +110,17 @@
 static request_hook_t *request_hook_chain = NULL;
 static response_hook_t *response_hook_chain = NULL;
 
-void blktap_register_ctrl_hook(char *name, int (*ch)(control_msg_t *)) 
+/* blktap_register_ctrl_hook returns -1 on error, 0 on success */ 
+int blktap_register_ctrl_hook(char *name, int (*ch)(control_msg_t *)) 
 {
     ctrl_hook_t *ch_ent, **c;
     
     ch_ent = (ctrl_hook_t *)malloc(sizeof(ctrl_hook_t));
-    if (!ch_ent) { printf("couldn't allocate a new hook\n"); exit(-1); }
+    if (!ch_ent) 
+    { 
+        DPRINTF("blktap_register_ctrl_hook: couldn't allocate a new hook\n"); 
+        return -1;
+    }
     
     ch_ent->func  = ch;
     ch_ent->next = NULL;
@@ -127,14 +132,20 @@
         c = &(*c)->next;
     }
     *c = ch_ent;
+    return 0;
 }
 
-void blktap_register_request_hook(char *name, int (*rh)(blkif_request_t *)) 
+/* blktap_register_request_hook returns -1 on error, 0 on success */ 
+int blktap_register_request_hook(char *name, int (*rh)(blkif_request_t *)) 
 {
     request_hook_t *rh_ent, **c;
     
     rh_ent = (request_hook_t *)malloc(sizeof(request_hook_t));
-    if (!rh_ent) { printf("couldn't allocate a new hook\n"); exit(-1); }
+    if (!rh_ent) 
+    { 
+        DPRINTF("blktap_register_request_hook: couldn't allocate a new hook\n"); 
+        return -1; 
+    }
     
     rh_ent->func  = rh;
     rh_ent->next = NULL;
@@ -145,14 +156,20 @@
         c = &(*c)->next;
     }
     *c = rh_ent;
+    return 0;
 }
 
-void blktap_register_response_hook(char *name, int (*rh)(blkif_response_t *)) 
+/* blktap_register_response_hook returns -1 on error, 0 on success */ 
+int blktap_register_response_hook(char *name, int (*rh)(blkif_response_t *)) 
 {
     response_hook_t *rh_ent, **c;
     
     rh_ent = (response_hook_t *)malloc(sizeof(response_hook_t));
-    if (!rh_ent) { printf("couldn't allocate a new hook\n"); exit(-1); }
+    if (!rh_ent) 
+    { 
+        DPRINTF("blktap_register_response_hook: couldn't allocate a new hook\n"); 
+        return -1;
+    }
     
     rh_ent->func  = rh;
     rh_ent->next = NULL;
@@ -163,6 +180,7 @@
         c = &(*c)->next;
     }
     *c = rh_ent;
+    return 0;
 }
 
 void print_hooks(void)
@@ -198,8 +216,6 @@
         
 /*-----[ Data to/from Backend (server) VM ]------------------------------*/
 
-
-
 inline int write_req_to_be_ring(blkif_request_t *req)
 {
     blkif_request_t *req_d;
@@ -289,7 +305,7 @@
     pollhook_t *ph;
     
     if (nr_pollhooks() == MAX_POLLFDS) {
-        printf("Too many pollhooks!\n");
+        DPRINTF("blktap_attach_poll: the number of pollhook reached the limit of %d!\n", MAX_POLLFDS);
         return -1;
     }
     
@@ -454,9 +470,9 @@
             }
             /* Using this as a unidirectional ring. */
             ctrl_ring.req_cons = ctrl_ring.rsp_prod_pvt = i;
-pthread_mutex_lock(&push_mutex);
+            pthread_mutex_lock(&push_mutex);
             RING_PUSH_RESPONSES(&ctrl_ring);
-pthread_mutex_unlock(&push_mutex);
+            pthread_mutex_unlock(&push_mutex);
             
             /* empty the fe_ring */
             notify_fe = 0;
@@ -524,18 +540,18 @@
 
             if (notify_be) {
                 DPRINTF("notifying be\n");
-pthread_mutex_lock(&push_mutex);
+                pthread_mutex_lock(&push_mutex);
                 RING_PUSH_REQUESTS(&be_ring);
                 ioctl(fd, BLKTAP_IOCTL_KICK_BE);
-pthread_mutex_unlock(&push_mutex);
+                pthread_mutex_unlock(&push_mutex);
             }
 
             if (notify_fe) {
                 DPRINTF("notifying fe\n");
-pthread_mutex_lock(&push_mutex);
+                pthread_mutex_lock(&push_mutex);
                 RING_PUSH_RESPONSES(&fe_ring);
                 ioctl(fd, BLKTAP_IOCTL_KICK_FE);
-pthread_mutex_unlock(&push_mutex);
+                pthread_mutex_unlock(&push_mutex);
             }
         }        
     }
===== tools/blktap/blktaplib.h 1.5 vs edited =====
--- 1.5/tools/blktap/blktaplib.h	2005-06-09 22:37:52 +09:00
+++ edited/tools/blktap/blktaplib.h	2005-06-13 16:41:48 +09:00
@@ -67,9 +67,15 @@
 inline unsigned int ID_TO_IDX(unsigned long id);
 inline domid_t ID_TO_DOM(unsigned long id);
 
-void blktap_register_ctrl_hook(char *name, int (*ch)(control_msg_t *));
-void blktap_register_request_hook(char *name, int (*rh)(blkif_request_t *));
-void blktap_register_response_hook(char *name, int (*rh)(blkif_response_t *));
+/* blktap_register_ctrl_hook returns -1 on error, 0 on success */ 
+int blktap_register_ctrl_hook(char *name, int (*ch)(control_msg_t *));
+
+/* blktap_register_request_hook returns -1 on error, 0 on success */ 
+int blktap_register_request_hook(char *name, int (*rh)(blkif_request_t *));
+
+/* blktap_register_response_hook returns -1 on error, 0 on success */ 
+int blktap_register_response_hook(char *name, int (*rh)(blkif_response_t *));
+
 void blktap_inject_response(blkif_response_t *);
 int  blktap_attach_poll(int fd, short events, int (*func)(int));
 void blktap_detach_poll(int fd);

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