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[PATCH 1/2] proc: fix inode number bogorithmetic

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Id which proc gets from IDR for inode number and id which proc removes
from IDR do not match. E.g. 0x11a transforms into 0x8000011a.

Which stayed unnoticed for a long time because, surprise, idr_remove()
masks out that high bit before doing anything.

All of this due to "| ~MAX_ID_MASK" in release_inode_number().

I still don't understand how it's supposed to work, because "| ~MASK"
is not an inversion for "& MAX" operation.

So, use just one nice, working addition. Make start offset unsigned int,
while I'm at it. It's longness is not used anywhere.

Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Alexey Dobriyan 2008-07-26 11:18:28 +04:00 committed by Al Viro
parent 8266602033
commit 67935df49d
1 changed files with 9 additions and 12 deletions
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21
fs/proc/generic.c
View File

@ -303,7 +303,7 @@ out:
static DEFINE_IDR(proc_inum_idr);
static DEFINE_SPINLOCK(proc_inum_lock); /* protects the above */
#define PROC_DYNAMIC_FIRST 0xF0000000UL
#define PROC_DYNAMIC_FIRST 0xF0000000U
/*
* Return an inode number between PROC_DYNAMIC_FIRST and
@ -311,7 +311,7 @@ static DEFINE_SPINLOCK(proc_inum_lock); /* protects the above */
*/
static unsigned int get_inode_number(void)
{
int i, inum = 0;
unsigned int i;
int error;
retry:
@ -326,21 +326,18 @@ retry:
else if (error)
return 0;
inum = (i & MAX_ID_MASK) + PROC_DYNAMIC_FIRST;
/* inum will never be more than 0xf0ffffff, so no check
* for overflow.
*/
return inum;
if (i > UINT_MAX - PROC_DYNAMIC_FIRST) {
spin_lock(&proc_inum_lock);
idr_remove(&proc_inum_idr, i);
spin_unlock(&proc_inum_lock);
}
return PROC_DYNAMIC_FIRST + i;
}
static void release_inode_number(unsigned int inum)
{
int id = (inum - PROC_DYNAMIC_FIRST) | ~MAX_ID_MASK;
spin_lock(&proc_inum_lock);
idr_remove(&proc_inum_idr, id);
idr_remove(&proc_inum_idr, inum - PROC_DYNAMIC_FIRST);
spin_unlock(&proc_inum_lock);
}