Re: [PATCH][FAT] FAT dirent scan with hin take #3

Machida, Hiroyuki
2005-08-31T12:57:59Z

Hi,

Pekka Enberg wrote:
> Hi,
>
> On 8/31/05, Machida, Hiroyuki <machida@sm.sony.co.jp> wrote:
>
>>+inline
>>+static int hint_allocate(struct inode *dir)
>>+{
>>+ loff_t *hints;
>>+ int err = 0;
>>+
>>+ if (!MSDOS_I(dir)->scan_hints) {
>>+ hints = kcalloc(FAT_SCAN_NWAY, sizeof(loff_t), GFP_KERNEL);
>>+ if (!hints)
>>+ err = -ENOMEM;
>
>
> Better to bail out here as...
>
>
>>+
>>+ down(&MSDOS_I(dir)->scan_lock);
>>+ if (MSDOS_I(dir)->scan_hints)
>>+ err = -EINVAL;
>
>
> ...you might overwrite -ENOMEM here masking the real problem.
>

It's ok. If MSDOS_I(dir)->scan_hints isn't NULL, it's not error case.
We need just kfree(hints) and return 0.(Assuming kfree() accepts NULL)
I think EINVAL confuse you.
>
>>+ if (!err)
>>+ MSDOS_I(dir)->scan_hints = hints;
>>+ up(&MSDOS_I(dir)->scan_lock);
>>+ if (err == -EINVAL) {
>
>
> Gotos would make error handling much cleaner.
>
How about this ?

if (!MSDOS_I(dir)->scan_hints) {
hints = kcalllo(....);

down
if (MSDOS_I(dir)->scan_hints) {
up
goto already_allocated;
}
if (hints)
MSDOS_I(dir)->scan_hints = hints;
up
}
return (hints == 0) ? -ENOMEM : 0;

already_allocated:
kfree(hints); /* kfree accepts NULL */
return 0;

>
>>+inline
>>+static int hint_index_body(const unsigned char *name, int name_len, int check_null)
>
>
> Please consider calling this __hint_index() instead as per normal
> naming conventions.

Agree.

>
>>+{
>>+ int i;
>>+ int val = 0;
>>+ unsigned char *p = (unsigned char *) name;
>>+ int id = current->pid;
>>+
>>+ for (i=0; i<name_len; i++) {
>>+ if (check_null && !*p) break;
>
>
> Please put break on separate line. You still have quite a few of these.

Agree

>
>
>>+ val = ((val << 1) & 0xfe) | ((val & 0x80) ? 1 : 0);
>>+ val ^= *p;
>>+ p ++;
>>+ }
>>+ id = ((id >> 8) & 0xf) ^ (id & 0xf);
>>+ val = (val << 1) | (id & 1);
>>+ return val & (FAT_SCAN_NWAY-1);
>>+}
>
>
> Pekka

--
Hiroyuki Machida machida@sm.sony.co.jp
SSW Dept. HENC, Sony Corp.