[PATCH 1/5] nbd: Fix debugfs error handling

[Markus Pargmann]

Static checker complains about the implemented error handling. It is
indeed wrong. We don't care about the return values of created debugfs
files.

We only have to check the return values of created dirs for NULL
pointer. If we use a null pointer as parent directory for files, this
may lead to debugfs files in wrong places.

Signed-off-by: Markus Pargmann 
---
 drivers/block/nbd.c | 61 -
 1 file changed, 18 insertions(+), 43 deletions(-)

diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
index 93b3f99b6865..b9e4179a950a 100644
--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c
@@ -891,57 +891,31 @@ static const struct file_operations nbd_dbg_flags_ops = {
 static int nbd_dev_dbg_init(struct nbd_device *nbd)
 {
struct dentry *dir;
-   struct dentry *f;
+
+   if (!nbd_dbg_dir)
+   return -EIO;
 
dir = debugfs_create_dir(nbd_name(nbd), nbd_dbg_dir);
-   if (IS_ERR_OR_NULL(dir)) {
-   dev_err(nbd_to_dev(nbd), "Failed to create debugfs dir for '%s' 
(%ld)\n",
-   nbd_name(nbd), PTR_ERR(dir));
-   return PTR_ERR(dir);
+   if (!dir) {
+   dev_err(nbd_to_dev(nbd), "Failed to create debugfs dir for 
'%s'\n",
+   nbd_name(nbd));
+   return -EIO;
}
nbd->dbg_dir = dir;
 
-   f = debugfs_create_file("tasks", 0444, dir, nbd, &nbd_dbg_tasks_ops);
-   if (IS_ERR_OR_NULL(f)) {
-   dev_err(nbd_to_dev(nbd), "Failed to create debugfs file 
'tasks', %ld\n",
-   PTR_ERR(f));
-   return PTR_ERR(f);
-   }
-
-   f = debugfs_create_u64("size_bytes", 0444, dir, &nbd->bytesize);
-   if (IS_ERR_OR_NULL(f)) {
-   dev_err(nbd_to_dev(nbd), "Failed to create debugfs file 
'size_bytes', %ld\n",
-   PTR_ERR(f));
-   return PTR_ERR(f);
-   }
-
-   f = debugfs_create_u32("timeout", 0444, dir, &nbd->xmit_timeout);
-   if (IS_ERR_OR_NULL(f)) {
-   dev_err(nbd_to_dev(nbd), "Failed to create debugfs file 
'timeout', %ld\n",
-   PTR_ERR(f));
-   return PTR_ERR(f);
-   }
-
-   f = debugfs_create_u32("blocksize", 0444, dir, &nbd->blksize);
-   if (IS_ERR_OR_NULL(f)) {
-   dev_err(nbd_to_dev(nbd), "Failed to create debugfs file 
'blocksize', %ld\n",
-   PTR_ERR(f));
-   return PTR_ERR(f);
-   }
-
-   f = debugfs_create_file("flags", 0444, dir, &nbd, &nbd_dbg_flags_ops);
-   if (IS_ERR_OR_NULL(f)) {
-   dev_err(nbd_to_dev(nbd), "Failed to create debugfs file 
'flags', %ld\n",
-   PTR_ERR(f));
-   return PTR_ERR(f);
-   }
+   debugfs_create_file("tasks", 0444, dir, nbd, &nbd_dbg_tasks_ops);
+   debugfs_create_u64("size_bytes", 0444, dir, &nbd->bytesize);
+   debugfs_create_u32("timeout", 0444, dir, &nbd->xmit_timeout);
+   debugfs_create_u32("blocksize", 0444, dir, &nbd->blksize);
+   debugfs_create_file("flags", 0444, dir, &nbd, &nbd_dbg_flags_ops);
 
return 0;
 }
 
 static void nbd_dev_dbg_close(struct nbd_device *nbd)
 {
-   debugfs_remove_recursive(nbd->dbg_dir);
+   if (nbd->dbg_dir)
+   debugfs_remove_recursive(nbd->dbg_dir);
 }
 
 static int nbd_dbg_init(void)
@@ -949,8 +923,8 @@ static int nbd_dbg_init(void)
struct dentry *dbg_dir;
 
dbg_dir = debugfs_create_dir("nbd", NULL);
-   if (IS_ERR(dbg_dir))
-   return PTR_ERR(dbg_dir);
+   if (!dbg_dir)
+   return -EIO;
 
nbd_dbg_dir = dbg_dir;
 
@@ -959,7 +933,8 @@ static int nbd_dbg_init(void)
 
 static void nbd_dbg_close(void)
 {
-   debugfs_remove_recursive(nbd_dbg_dir);
+   if (nbd_dbg_dir)
+   debugfs_remove_recursive(nbd_dbg_dir);
 }
 
 #else  /* IS_ENABLED(CONFIG_DEBUG_FS) */
-- 
2.6.2

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Re: [PATCH 1/5] nbd: Fix debugfs error handling

[kbuild test robot]

Hi Markus,

[auto build test WARNING on block/for-next]
[also build test WARNING on v4.4-rc7 next-20151231]
[if your patch is applied to the wrong git tree, please drop us a note to help 
improving the system]

url:
https://github.com/0day-ci/linux/commits/Markus-Pargmann/nbd-Fix-debugfs-error-handling/20160102-182030
base:   https://git.kernel.org/pub/scm/linux/kernel/git/axboe/linux-block.git 
for-next


coccinelle warnings: (new ones prefixed by >>)

>> drivers/block/nbd.c:937:2-26: WARNING: NULL check before freeing functions 
>> like kfree, debugfs_remove, debugfs_remove_recursive or usb_free_urb is not 
>> needed. Maybe consider reorganizing relevant code to avoid passing NULL 
>> values.
   drivers/block/nbd.c:918:2-26: WARNING: NULL check before freeing functions 
like kfree, debugfs_remove, debugfs_remove_recursive or usb_free_urb is not 
needed. Maybe consider reorganizing relevant code to avoid passing NULL values.

Please review and possibly fold the followup patch.

---
0-DAY kernel test infrastructureOpen Source Technology Center
https://lists.01.org/pipermail/kbuild-all   Intel Corporation
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