Re: [TRIVIAL] Error checks omitted in init_tmpfs() in mm/tiny-shmem.c

[Hareesh Nagarajan <hnagar2@gmail.com>]

[-- Attachment #1: Type: text/plain, Size: 1488 bytes --]

Matt Mackall wrote:
> On Mon, Oct 24, 2005 at 03:56:47AM -0500, Hareesh Nagarajan wrote:
>> Matt Mackall wrote:
>>> On Mon, Oct 24, 2005 at 12:29:45AM -0500, Hareesh Nagarajan wrote:
>>>> The existing code in init_tmpfs() in mm/tiny-shmem.c does not handle the 
>>>> cases when the calls to register_filesystem() and kern_mount() fail. 
>>>> This patch adds those checks.

[ Snip ]

> A couple more comments..
> 
>> Signed-off-by: Hareesh Nagarajan <hnagar2@gmail.com>
> 
>> --- linux-2.6.13.4/mm/tiny-shmem.c	2005-10-10 13:54:29.000000000 -0500
>> +++ linux-2.6.13.4-edit/mm/tiny-shmem.c	2005-10-24 03:43:38.614071000 -0500
>> @@ -31,12 +31,18 @@
>>  
>>  static int __init init_tmpfs(void)
>>  {
>> -	register_filesystem(&tmpfs_fs_type);
>> +	int error;
>> +
>> +	error = register_filesystem(&tmpfs_fs_type);
>> +	BUG_ON(error);
> 
> Can we just do BUG_ON(register_filesystem() != 0)?
> 
> Strictly speaking, the != 0 is redundant, but as this goes slightly
> against the grain of normal usage, it's a good indicator of intent.

It shows intent well. That goes into my book for good programming 
practices. No more BUG_ON(foo) :)

>>  #ifdef CONFIG_TMPFS
>>  	devfs_mk_dir("shm");
>>  #endif
>>  	shm_mnt = kern_mount(&tmpfs_fs_type);
>> -	return 0;
>> +	BUG_ON(IS_ERR(shm_mnt));
>> +
>> +	return error;
> 
> We can never return non-zero here. Returning error implies we can, so
> it's confusing.

Makes sense again. Patch follows.

Signed-off-by: Hareesh Nagarajan <hnagar2@gmail.com>

[-- Attachment #2: tiny-shmmem-fix-ver3.patch --]
[-- Type: text/x-patch, Size: 462 bytes --]

--- linux-2.6.13.4/mm/tiny-shmem.c	2005-10-10 13:54:29.000000000 -0500
+++ linux-2.6.13.4-edit/mm/tiny-shmem.c	2005-10-24 19:05:28.058897000 -0500
@@ -31,11 +31,14 @@
 
 static int __init init_tmpfs(void)
 {
-	register_filesystem(&tmpfs_fs_type);
+	BUG_ON(register_filesystem(&tmpfs_fs_type) != 0);
+
 #ifdef CONFIG_TMPFS
 	devfs_mk_dir("shm");
 #endif
 	shm_mnt = kern_mount(&tmpfs_fs_type);
+	BUG_ON(IS_ERR(shm_mnt));
+
 	return 0;
 }
 module_init(init_tmpfs)