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

Hareesh Nagarajan
2005-10-25T00:16:55Z

[-- 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)