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Date: Thu, 4 Apr 2024 17:34:42 +0300
From: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
To: Tony Lindgren <tony@atomide.com>
Cc: kernel test robot <oliver.sang@intel.com>,
	Yicong Yang <yangyicong@hisilicon.com>, oe-lkp@lists.linux.dev,
	lkp@intel.com, linux-kernel@vger.kernel.org,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	stable <stable@kernel.org>, linux-serial@vger.kernel.org
Subject: Re: [linus:master] [serial]  43066e3222:
 BUG:kernel_NULL_pointer_dereference,address
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References: <202404031607.2e92eebe-lkp@intel.com>
 <Zg1hBvRAxifo50sf@smile.fi.intel.com>
 <20240404065415.GO5132@atomide.com>
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On Thu, Apr 04, 2024 at 09:54:15AM +0300, Tony Lindgren wrote:
> * Andy Shevchenko <andriy.shevchenko@linux.intel.com> [240403 14:00]:
> > Probably we need to check if the port is still open...
> > 
> > P.S. AFAIU the state / xmit is invalid pointer or so.
> > 
> > Culprit line:	serial_out(up, UART_TX, xmit->buf[xmit->tail]);
> 
> Maybe we can set UPF_DEAD a bit earlier as below?

We should do this under port_mutex. Otherwise we replace one race by another.

-- 
With Best Regards,
Andy Shevchenko