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SubjectRe: 2.6.14 kernels and above copy_to_user stupidity with IRQ disabled check
Phillip Susi wrote:

> jmerkey@ns1.utah-nac.org wrote:
>
>> OK. Got it. I guess I need to restructure. And BTW, This was a
>> code fragment
>> only, the spinlock gets released when -EFAULT is called -- was just
>> an example.
>>
>> Jeff
>
>
> Unless you have redefined EFAULT in some strange and hideous way, it
> is not "called" and doesn't free the spinlock. EFAULT is defined as a
> literal integer, so you're just returning a number without freeing the
> spinlock.
>
> If you have redefined EFAULT to a macro function call or whatever,
> then don't do that, it's REALLY horrible coding practice.
>
>
No. I posted a code fragment as an example. Here's the actual code:

int dump_regen(VIRTUAL_SETUP *s, ULONG count)
{
register int i = 0;
VIRTUAL_SETUP *v;


spin_lock_irqsave(&regen_lock, regen_flags);
v = regen_head;
while (v)
{
if (i >= count)
{
spin_unlock_irqrestore(&regen_lock, regen_flags);
return -EFAULT;
}


err = copy_to_user(&s[i++], v, sizeof(VIRTUAL_SETUP));
if (err)
{
spin_unlock_irqrestore(&regen_lock, regen_flags);
return err;
}

v = v->next;
}
spin_unlock_irqrestore(&regen_lock, regen_flags);
return 0;
}

Needless to say, this has been restructured to this:

int dump_regen(VIRTUAL_SETUP *s, ULONG count)
{
register int i = 0;
VIRTUAL_SETUP *v;


spin_lock_irqsave(&regen_lock, regen_flags);
v = regen_head;
while (v)
{
if (i >= count)
{
spin_unlock_irqrestore(&regen_lock, regen_flags);
return 0;
}


P_Copy(&s[i++], v, sizeof(VIRTUAL_SETUP));
v = v->next;
}
spin_unlock_irqrestore(&regen_lock, regen_flags);
return 0;
}


Jeff

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