linux-kernel - Re: [RESEND] serial: 8250_bcm7271: move spin_lock_irqsave to spin

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Message-ID: <CAEVeK2AiYFK9eopn1Uzp+osA-j22e1KbfUohJ+hRVmLNsq0gpQ@mail.gmail.com>
Date:   Sat, 27 Aug 2022 17:42:19 +0800
From:   tuo cao <91tuocao@...il.com>
To:     Greg KH <gregkh@...uxfoundation.org>
Cc:     alcooperx@...il.com, bcm-kernel-feedback-list@...adcom.com,
        jirislaby@...nel.org, linux-serial@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [RESEND] serial: 8250_bcm7271: move spin_lock_irqsave to
 spin_lock in interrupt handler

No, whether it's spin_lock_irqsave() or spin_lock(), the security is
the same. Since this commit:e58aa3d2d0cc01ad8d6f7f640a0670433f794922,
interrupt nesting is disabled, which means interrupts has disabled in
the interrupt handlers. So, it is unnecessary to call
spin_lock_irqsave in a interrupt handler. And it takes less time
obviously to use spin_lock()，so I think this change is needed.

Finally, I'm sorry I lacked real hardware to verify it and can't
provide changelog text.

Thanks.

Greg KH <gregkh@...uxfoundation.org> 于2022年8月22日周一 22:25写道：
>
> On Mon, Aug 22, 2022 at 10:11:10PM +0800, Tuo Cao wrote:
> > it is unnecessary to call spin_lock_irqsave in a interrupt handler.
>
> Yes, but it is safer to do so, right?
>
> Why is this change needed?
>
> Did you test it on real hardware to verify it works?
>
> We need a lot more information in the changelog text before being able
> to accept this.
>
> thanks,
>
> greg k-h