linux-kernel - Re: [PATCH] serial: 8250: 8250_omap: Fix possible interrupt storm

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Message-ID: <YLCxLvcm/yG9+GE3@kroah.com>
Date:   Fri, 28 May 2021 11:00:30 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     Vignesh Raghavendra <vigneshr@...com>
Cc:     Tony Lindgren <tony@...mide.com>,
        Jiri Slaby <jirislaby@...nel.org>,
        Jan Kiszka <jan.kiszka@...mens.com>,
        linux-serial@...r.kernel.org, linux-omap@...r.kernel.org,
        Linux ARM Mailing List <linux-arm-kernel@...ts.infradead.org>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] serial: 8250: 8250_omap: Fix possible interrupt storm

On Fri, May 28, 2021 at 11:41:36AM +0530, Vignesh Raghavendra wrote:
> Hi,
> 
> On 5/28/21 11:09 AM, Tony Lindgren wrote:
> > Hi Greg, Vignesh & Jan,
> > 
> > * Greg Kroah-Hartman <gregkh@...uxfoundation.org> [210513 14:17]:
> >> On Tue, May 11, 2021 at 08:49:55PM +0530, Vignesh Raghavendra wrote:
> >>> It is possible that RX TIMEOUT is signalled after RX FIFO has been
> >>> drained, in which case a dummy read of RX FIFO is required to clear RX
> >>> TIMEOUT condition. Otherwise, RX TIMEOUT condition is not cleared
> >>> leading to an interrupt storm
> >>>
> >>> Cc: stable@...r.kernel.org
> >>
> >> How far back does this need to go?  What commit id does this fix?  What
> >> caused this to just show up now vs. previously?
> 
> Sorry, I missed this reply. Issue was reported on AM65x SoC with custom
> test case from Jan Kiszka that stressed UART with rapid baudrate changes
> from 9600 to 4M along with data transfer.
> 
> Based on the condition that led to interrupt storm, I inferred it to
> affect all SoCs with 8250 OMAP UARTs. But that seems thats not the best
> idea as seen from OMAP3 regression.
> 
> Greg,
> 
> Could you please drop the patch? Very sorry for the inconvenience..

Now reverted, thanks.

greg k-h