On Sat, Mar 3, 2012 at 2:43 AM, David Miller <davem@xxxxxxxxxxxxx> wrote:
> From: santosh prasad nayak <santoshprasadnayak@xxxxxxxxx>
> Date: Fri, 2 Mar 2012 21:24:29 +0530
>
>> In "ql_adapter_initialize", first unlock is done by
>> "spin_unlock_irqrestore(&qdev->hw_lock, hw_flags)"
>> with "hw_flags = 0" ("hw_flags" is local variable and initialized to
>> zero.), which is as good as
>> spin_unlock_irq.
>
> You must never pass to irqrestore anything other than a hw_flags
> value given by irqsave or similar.
David,
Thats what my point is.
The function call is as follow:
ql_adapter_up()
{
.....
spin_lock_irqsave(&qdev->hw_lock, hw_flags);
.....
err = ql_adapter_initialize(qdev);
.....
spin_unlock_irqrestore(&qdev->hw_lock, hw_flags);
......
}
ql_adapter_initialize()
{
unsigned long hw_flags = 0; // D
.......
spin_unlock_irqrestore(&qdev->hw_lock, hw_flags); // A
msleep(500); // B
spin_lock_irqsave(&qdev->hw_lock, hw_flags); // C
.....
}
In ql_adapter_initialize, at A,
'spin_unlock_irqrestore' is called with "hw_flags = 0",
which is as good as spin_unlock_irq().
Static analyzer is showing it as "Error : bogus hw_flags",
which is true. Because "hw_flags" is initialized to zero at D
and the same "hw_flags" is used to restore IRQ at A.
If intention of the developer is to unlock and enable IRQ
at A then we can use "spin_unlock_irq()" which will
remove the static analyzer error and also give better
performance.
Regards
Santosh
> You may not assume anything about what values hw_flags takes on nor
> what those values might mean, they are architecture specific so
> you may not just set it to zero and assume that does anything in
> particular.
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