1 files changed, 64 insertions, 83 deletions

diff --git a/fs/orangefs/orangefs-debugfs.c b/fs/orangefs/orangefs-debugfs.c
index eb09aa026723..d484068ca716 100644
--- a/fs/orangefs/orangefs-debugfs.c
+++ b/fs/orangefs/orangefs-debugfs.c
@@ -141,6 +141,9 @@ static struct client_debug_mask client_debug_mask;
  */
 static DEFINE_MUTEX(orangefs_debug_lock);
 
+/* Used to protect data in ORANGEFS_KMOD_DEBUG_HELP_FILE */
+static DEFINE_MUTEX(orangefs_help_file_lock);
+
 /*
  * initialize kmod debug operations, create orangefs debugfs dir and
  * ORANGEFS_KMOD_DEBUG_HELP_FILE.
@@ -289,6 +292,8 @@ static void *help_start(struct seq_file *m, loff_t *pos)
 
         gossip_debug(GOSSIP_DEBUGFS_DEBUG, "help_start: start\n");
 
+        mutex_lock(&orangefs_help_file_lock);
+
         if (*pos == 0)
                 payload = m->private;
 
@@ -305,6 +310,7 @@ static void *help_next(struct seq_file *m, void *v, loff_t *pos)
 static void help_stop(struct seq_file *m, void *p)
 {
         gossip_debug(GOSSIP_DEBUGFS_DEBUG, "help_stop: start\n");
+        mutex_unlock(&orangefs_help_file_lock);
 }
 
 static int help_show(struct seq_file *m, void *v)
@@ -610,32 +616,54 @@ out:
  * /sys/kernel/debug/orangefs/debug-help can be catted to
  * see all the available kernel and client debug keywords.
  *
- * When the kernel boots, we have no idea what keywords the
+ * When orangefs.ko initializes, we have no idea what keywords the
  * client supports, nor their associated masks.
  *
- * We pass through this function once at boot and stamp a
+ * We pass through this function once at module-load and stamp a
  * boilerplate "we don't know" message for the client in the
  * debug-help file. We pass through here again when the client
  * starts and then we can fill out the debug-help file fully.
  *
  * The client might be restarted any number of times between
- * reboots, we only build the debug-help file the first time.
+ * module reloads, we only build the debug-help file the first time.
  */
 int orangefs_prepare_debugfs_help_string(int at_boot)
 {
-        int rc = -EINVAL;
-        int i;
-        int byte_count = 0;
         char *client_title = "Client Debug Keywords:\n";
         char *kernel_title = "Kernel Debug Keywords:\n";
+        size_t string_size =  DEBUG_HELP_STRING_SIZE;
+        size_t result_size;
+        size_t i;
+        char *new;
+        int rc = -EINVAL;
 
         gossip_debug(GOSSIP_UTILS_DEBUG, "%s: start\n", __func__);
 
-        if (at_boot) {
-                byte_count += strlen(HELP_STRING_UNINITIALIZED);
+        if (at_boot)
                 client_title = HELP_STRING_UNINITIALIZED;
-        } else {
-                /*
+
+        /* build a new debug_help_string. */
+        new = kzalloc(DEBUG_HELP_STRING_SIZE, GFP_KERNEL);
+        if (!new) {
+                rc = -ENOMEM;
+                goto out;
+        }
+
+        /*
+         * strlcat(dst, src, size) will append at most
+         * "size - strlen(dst) - 1" bytes of src onto dst,
+         * null terminating the result, and return the total
+         * length of the string it tried to create.
+         *
+         * We'll just plow through here building our new debug
+         * help string and let strlcat take care of assuring that
+         * dst doesn't overflow.
+         */
+        strlcat(new, client_title, string_size);
+
+        if (!at_boot) {
+
+                /*
                  * fill the client keyword/mask array and remember
                  * how many elements there were.
                  */
@@ -644,64 +672,40 @@ int orangefs_prepare_debugfs_help_string(int at_boot)
                 if (cdm_element_count <= 0)
                         goto out;
 
-                /* Count the bytes destined for debug_help_string. */
-                byte_count += strlen(client_title);
-
                 for (i = 0; i < cdm_element_count; i++) {
-                        byte_count += strlen(cdm_array[i].keyword + 2);
-                        if (byte_count >= DEBUG_HELP_STRING_SIZE) {
-                                pr_info("%s: overflow 1!\n", __func__);
-                                goto out;
-                        }
+                        strlcat(new, "\t", string_size);
+                        strlcat(new, cdm_array[i].keyword, string_size);
+                        strlcat(new, "\n", string_size);
                 }
-
-                gossip_debug(GOSSIP_UTILS_DEBUG,
-                             "%s: cdm_element_count:%d:\n",
-                             __func__,
-                             cdm_element_count);
         }
 
-        byte_count += strlen(kernel_title);
+        strlcat(new, "\n", string_size);
+        strlcat(new, kernel_title, string_size);
+
         for (i = 0; i < num_kmod_keyword_mask_map; i++) {
-                byte_count +=
-                        strlen(s_kmod_keyword_mask_map[i].keyword + 2);
-                if (byte_count >= DEBUG_HELP_STRING_SIZE) {
-                        pr_info("%s: overflow 2!\n", __func__);
-                        goto out;
-                }
+                strlcat(new, "\t", string_size);
+                strlcat(new, s_kmod_keyword_mask_map[i].keyword, string_size);
+                result_size = strlcat(new, "\n", string_size);
         }
 
-        /* build debug_help_string. */
-        debug_help_string = kzalloc(DEBUG_HELP_STRING_SIZE, GFP_KERNEL);
-        if (!debug_help_string) {
-                rc = -ENOMEM;
+        /* See if we tried to put too many bytes into "new"... */
+        if (result_size >= string_size) {
+                kfree(new);
                 goto out;
         }
 
-        strcat(debug_help_string, client_title);
-
-        if (!at_boot) {
-                for (i = 0; i < cdm_element_count; i++) {
-                        strcat(debug_help_string, "\t");
-                        strcat(debug_help_string, cdm_array[i].keyword);
-                        strcat(debug_help_string, "\n");
-                }
-        }
-
-        strcat(debug_help_string, "\n");
-        strcat(debug_help_string, kernel_title);
-
-        for (i = 0; i < num_kmod_keyword_mask_map; i++) {
-                strcat(debug_help_string, "\t");
-                strcat(debug_help_string, s_kmod_keyword_mask_map[i].keyword);
-                strcat(debug_help_string, "\n");
+        if (at_boot) {
+                debug_help_string = new;
+        } else {
+                mutex_lock(&orangefs_help_file_lock);
+                memset(debug_help_string, 0, DEBUG_HELP_STRING_SIZE);
+                strlcat(debug_help_string, new, string_size);
+                mutex_unlock(&orangefs_help_file_lock);
         }
 
         rc = 0;
 
-out:
-
-        return rc;
+out:    return rc;
 
 }
 
@@ -959,8 +963,12 @@ int orangefs_debugfs_new_client_string(void __user *arg)
         ret = copy_from_user(&client_debug_array_string,
                                      (void __user *)arg,
                                      ORANGEFS_MAX_DEBUG_STRING_LEN);
-        if (ret != 0)
+
+        if (ret != 0) {
+                pr_info("%s: CLIENT_STRING: copy_from_user failed\n",
+                        __func__);
                 return -EIO;
+        }
 
         /*
          * The real client-core makes an effort to ensure
@@ -975,45 +983,18 @@ int orangefs_debugfs_new_client_string(void __user *arg)
         client_debug_array_string[ORANGEFS_MAX_DEBUG_STRING_LEN - 1] =
                 '\0';
         
-        if (ret != 0) {
-                pr_info("%s: CLIENT_STRING: copy_from_user failed\n",
-                        __func__);
-                return -EIO;
-        }
-
         pr_info("%s: client debug array string has been received.\n",
                 __func__);
 
         if (!help_string_initialized) {
 
-                /* Free the "we don't know yet" default string... */
-                kfree(debug_help_string);
-
-                /* build a proper debug help string */
+                /* Build a proper debug help string. */
                 if (orangefs_prepare_debugfs_help_string(0)) {
                         gossip_err("%s: no debug help string \n",
                                    __func__);
                         return -EIO;
                 }
 
-                /* Replace the boilerplate boot-time debug-help file. */
-                debugfs_remove(help_file_dentry);
-
-                help_file_dentry =
-                        debugfs_create_file(
-                                ORANGEFS_KMOD_DEBUG_HELP_FILE,
-                                0444,
-                                debug_dir,
-                                debug_help_string,
-                                &debug_help_fops);
-
-                if (!help_file_dentry) {
-                        gossip_err("%s: debugfs_create_file failed for"
-                                   " :%s:!\n",
-                                   __func__,
-                                   ORANGEFS_KMOD_DEBUG_HELP_FILE);
-                        return -EIO;
-                }
         }
 
         debug_mask_to_string(&client_debug_mask, 1);