[rds-devel] [PATCH 2/5] rds: ib: replace spin_lock_irq with spin_lock_irqsave
santosh.shilimkar at oracle.com
santosh.shilimkar at oracle.com
Sat Mar 11 22:37:39 PST 2017
On 3/11/17 6:33 PM, Yanjun Zhu wrote:
> Sorry. I have no test case to show some issue.
> But from Linux Kernel Development Second Edition by Robert Love.
>
Yes I know the book and what the API does :D
> Use spin_lock_irq is dangerous since spin_unlock_irq unconditionally
> enables interrupts.
>
> We can assume the following scenario:
>
> --->the interrupt is disabled.
>
> spin_lock_irq(lock_ptr); <---this will disable interrupt again
> list_del(&ic->ib_node);
> spin_unlock_irq(lock_ptr); <---this will enable interrupt
>
> ---->the interrupt is enabled.
>
> our code change the state of interrupt. This will make potential risk.
> But spin_lock_irqsave/spin_unlock_irqrestore will not make potential risk.
>
ic is well protected for any possible race and hence I asked
if you had any test case. Please re-post the series again with
the subject patch dropper for Dave to pick it up.
Regards,
Santosh
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