Re: Patch "serial: 8250_dw: Fix deadlock in LCR workaround" has been added to the 3.19-stable tree

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On Fri, Mar 27, 2015 at 02:48:55PM +0800, Zhang Zhen wrote:
> Hi Greg,
> 
> The 3.10-stable tree needs this patch too.
> Can you push this patch to 3.10 stable tree ?
> 
> Best regards!
>

I'll queue this for the 3.16 kernel as well -- the backport seems to
be trivial (simply dropping changes to dw8250_serial_outq()).

Cheers,
--
Luís


> On 2015/3/24 18:35, gregkh@xxxxxxxxxxxxxxxxxxx wrote:
> > 
> > This is a note to let you know that I've just added the patch titled
> > 
> >     serial: 8250_dw: Fix deadlock in LCR workaround
> > 
> > to the 3.19-stable tree which can be found at:
> >     http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
> > 
> > The filename of the patch is:
> >      serial-8250_dw-fix-deadlock-in-lcr-workaround.patch
> > and it can be found in the queue-3.19 subdirectory.
> > 
> > If you, or anyone else, feels it should not be added to the stable tree,
> > please let <stable@xxxxxxxxxxxxxxx> know about it.
> > 
> > 
> >>From 7fd6f640f2dd17dac6ddd6702c378cb0bb9cfa11 Mon Sep 17 00:00:00 2001
> > From: Peter Hurley <peter@xxxxxxxxxxxxxxxxxx>
> > Date: Wed, 11 Mar 2015 09:19:16 -0400
> > Subject: serial: 8250_dw: Fix deadlock in LCR workaround
> > 
> > From: Peter Hurley <peter@xxxxxxxxxxxxxxxxxx>
> > 
> > commit 7fd6f640f2dd17dac6ddd6702c378cb0bb9cfa11 upstream.
> > 
> > Trying to write console output from within the serial console driver
> > while the port->lock is held causes recursive deadlock:
> > 
> >   CPU 0
> > spin_lock_irqsave(&port->lock)
> > printk()
> >   console_unlock()
> >     call_console_drivers()
> >       serial8250_console_write()
> >         spin_lock_irqsave(&port->lock)
> > ** DEADLOCK **
> > 
> > The 8250_dw i/o accessors try to write a console error message if the
> > LCR workaround was unsuccessful. When the port->lock is already held
> > (eg., when called from serial8250_set_termios()), this deadlocks.
> > 
> > Make the error message a FIXME until a general solution is devised.
> > 
> > Cc: Tim Kryger <tim.kryger@xxxxxxxxx>
> > Reported-by: Zhang Zhen <zhenzhang.zhang@xxxxxxxxxx>
> > Signed-off-by: Peter Hurley <peter@xxxxxxxxxxxxxxxxxx>
> > Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
> > 
> > ---
> >  drivers/tty/serial/8250/8250_dw.c |   15 ++++++++++++---
> >  1 file changed, 12 insertions(+), 3 deletions(-)
> > 
> > --- a/drivers/tty/serial/8250/8250_dw.c
> > +++ b/drivers/tty/serial/8250/8250_dw.c
> > @@ -111,7 +111,10 @@ static void dw8250_serial_out(struct uar
> >  			dw8250_force_idle(p);
> >  			writeb(value, p->membase + (UART_LCR << p->regshift));
> >  		}
> > -		dev_err(p->dev, "Couldn't set LCR to %d\n", value);
> > +		/*
> > +		 * FIXME: this deadlocks if port->lock is already held
> > +		 * dev_err(p->dev, "Couldn't set LCR to %d\n", value);
> > +		 */
> >  	}
> >  }
> >  
> > @@ -155,7 +158,10 @@ static void dw8250_serial_outq(struct ua
> >  			__raw_writeq(value & 0xff,
> >  				     p->membase + (UART_LCR << p->regshift));
> >  		}
> > -		dev_err(p->dev, "Couldn't set LCR to %d\n", value);
> > +		/*
> > +		 * FIXME: this deadlocks if port->lock is already held
> > +		 * dev_err(p->dev, "Couldn't set LCR to %d\n", value);
> > +		 */
> >  	}
> >  }
> >  #endif /* CONFIG_64BIT */
> > @@ -179,7 +185,10 @@ static void dw8250_serial_out32(struct u
> >  			dw8250_force_idle(p);
> >  			writel(value, p->membase + (UART_LCR << p->regshift));
> >  		}
> > -		dev_err(p->dev, "Couldn't set LCR to %d\n", value);
> > +		/*
> > +		 * FIXME: this deadlocks if port->lock is already held
> > +		 * dev_err(p->dev, "Couldn't set LCR to %d\n", value);
> > +		 */
> >  	}
> >  }
> >  
> > 
> > 
> > Patches currently in stable-queue which might be from peter@xxxxxxxxxxxxxxxxxx are
> > 
> > queue-3.19/serial-core-fix-iotype-userspace-breakage.patch
> > queue-3.19/console-fix-console-name-size-mismatch.patch
> > queue-3.19/serial-8250_dw-fix-deadlock-in-lcr-workaround.patch
> > 
> > .
> > 
> 
> 
> --
> To unsubscribe from this list: send the line "unsubscribe stable" in
> the body of a message to majordomo@xxxxxxxxxxxxxxx
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
--
To unsubscribe from this list: send the line "unsubscribe stable" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html




[Index of Archives]     [Linux Kernel]     [Kernel Development Newbies]     [Linux USB Devel]     [Video for Linux]     [Linux Audio Users]     [Yosemite Hiking]     [Linux Kernel]     [Linux SCSI]