[PATCH] uml: return hotplug errors to host

[powerpc.git] / arch / um / drivers / mconsole_kern.c

diff --git a/arch/um/drivers/mconsole_kern.c b/arch/um/drivers/mconsole_kern.c
index 96f0189..832d5c7 100644 (file)
--- a/arch/um/drivers/mconsole_kern.c
+++ b/arch/um/drivers/mconsole_kern.c
@@ -371,14 +371,16 @@ static unsigned long long unplugged_pages_count = 0;
 static struct list_head unplugged_pages = LIST_HEAD_INIT(unplugged_pages);
 static int unplug_index = UNPLUGGED_PER_PAGE;
 
-static int mem_config(char *str)
+static int mem_config(char *str, char **error_out)
 {
        unsigned long long diff;
        int err = -EINVAL, i, add;
        char *ret;
 
-       if(str[0] != '=')
+       if(str[0] != '='){
+               *error_out = "Expected '=' after 'mem'";
                goto out;
+       }
 
        str++;
        if(str[0] == '-')
@@ -386,12 +388,17 @@ static int mem_config(char *str)
        else if(str[0] == '+'){
                add = 1;
        }
-       else goto out;
+       else {
+               *error_out = "Expected increment to start with '-' or '+'";
+               goto out;
+       }
 
        str++;
        diff = memparse(str, &ret);
-       if(*ret != '\0')
+       if(*ret != '\0'){
+               *error_out = "Failed to parse memory increment";
                goto out;
+       }
 
        diff /= PAGE_SIZE;
 
@@ -435,11 +442,14 @@ static int mem_config(char *str)
                                unplugged = list_entry(entry,
                                                       struct unplugged_pages,
                                                       list);
-                               unplugged->pages[unplug_index++] = addr;
                                err = os_drop_memory(addr, PAGE_SIZE);
-                               if(err)
+                               if(err){
                                        printk("Failed to release memory - "
                                               "errno = %d\n", err);
+                                       *error_out = "Failed to release memory";
+                                       goto out;
+                               }
+                               unplugged->pages[unplug_index++] = addr;
                        }
 
                        unplugged_pages_count++;
@@ -470,8 +480,9 @@ static int mem_id(char **str, int *start_out, int *end_out)
        return 0;
 }
 
-static int mem_remove(int n)
+static int mem_remove(int n, char **error_out)
 {
+       *error_out = "Memory doesn't support the remove operation";
        return -EBUSY;
 }
 
@@ -542,7 +553,7 @@ static void mconsole_get_config(int (*get_config)(char *, char *, int,
 void mconsole_config(struct mc_request *req)
 {
        struct mc_device *dev;
-       char *ptr = req->request.data, *name;
+       char *ptr = req->request.data, *name, *error_string = "";
        int err;
 
        ptr += strlen("config");
@@ -559,8 +570,8 @@ void mconsole_config(struct mc_request *req)
                ptr++;
 
        if(*ptr == '='){
-               err = (*dev->config)(name);
-               mconsole_reply(req, "", err, 0);
+               err = (*dev->config)(name, &error_string);
+               mconsole_reply(req, error_string, err, 0);
        }
        else mconsole_get_config(dev->get_config, req, name);
 }
@@ -595,13 +606,16 @@ void mconsole_remove(struct mc_request *req)
                goto out;
        }
 
-       err = (*dev->remove)(n);
+       err_msg = NULL;
+       err = (*dev->remove)(n, &err_msg);
        switch(err){
        case -ENODEV:
-               err_msg = "Device doesn't exist";
+               if(err_msg == NULL)
+                       err_msg = "Device doesn't exist";
                break;
        case -EBUSY:
-               err_msg = "Device is currently open";
+               if(err_msg == NULL)
+                       err_msg = "Device is currently open";
                break;
        default:
                break;