linux-kernel - Re: [PATCH] tty: Remove pointless synchronize_irq() in uart_port

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Message-ID: <d157042-39ed-7b56-a40-e0c6c1e3f3db@pcs.com>
Date:   Wed, 11 May 2022 09:48:47 +0200
From:   Thomas Pfaff <tpfaff@....com>
To:     Jiri Slaby <jirislaby@...nel.org>
CC:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] tty: Remove pointless synchronize_irq() in
 uart_port_shutdown()



On Wed, 11 May 2022, Jiri Slaby wrote:

> On 10. 05. 22, 15:54, Thomas Pfaff wrote:
> > From: Thomas Pfaff <tpfaff@....com>
> > 
> > Calling synchronize_irq() after free_irq() is pointless, the context to
> > the irq is already lost.
> > It was noticed while creating the bugfix "genirq: Synchronize interrupt
> > thread startup".
> 
> That's correct for most drivers. But some drivers don't call free_irq() in
> ->shutdown(). So you likely have to move the synchronization to them. By a
> quick grep, I found icom, jsm, sccnxp, sifive, sunhv, and sunzilog.
> 

Sorry, I did not check all the drivers.
Then I would keep it in serial_core, as it does not hurt anymore.

Thanks,
    Thomas