linux-stable.git/drivers/tty/serial/sh-sci.c, branch v3.16.67 Linux kernel stable tree serial: sh-sci: prevent lockup on full TTY buffers 2018-06-16T21:22:29+00:00 Ulrich Hecht ulrich.hecht+renesas@gmail.com 2018-02-15T12:02:27+00:00 ec88bd138bb46068f6efd99a96b8cf1f6f1e66d2 commit 7842055bfce4bf0170d0f61df8b2add8399697be upstream. When the TTY buffers fill up to the configured maximum, a system lockup occurs: [ 598.820128] INFO: rcu_preempt detected stalls on CPUs/tasks: [ 598.825796] 0-...!: (1 GPs behind) idle=5a6/2/0 softirq=1974/1974 fqs=1 [ 598.832577] (detected by 3, t=62517 jiffies, g=296, c=295, q=126) [ 598.838755] Task dump for CPU 0: [ 598.841977] swapper/0 R running task 0 0 0 0x00000022 [ 598.849023] Call trace: [ 598.851476] __switch_to+0x98/0xb0 [ 598.854870] (null) This can be prevented by doing a dummy read of the RX data register. This issue affects both HSCIF and SCIF ports. Reported for R-Car H3 ES2.0; reproduced and fixed on H3 ES1.1. Probably affects other R-Car platforms as well. Reported-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com> Signed-off-by: Ulrich Hecht <ulrich.hecht+renesas@gmail.com> Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be> Tested-by: Nguyen Viet Dung <dung.nguyen.aj@renesas.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> 
commit 7842055bfce4bf0170d0f61df8b2add8399697be upstream.

When the TTY buffers fill up to the configured maximum, a system lockup
occurs:

[  598.820128] INFO: rcu_preempt detected stalls on CPUs/tasks:
[  598.825796]  0-...!: (1 GPs behind) idle=5a6/2/0 softirq=1974/1974 fqs=1
[  598.832577]  (detected by 3, t=62517 jiffies, g=296, c=295, q=126)
[  598.838755] Task dump for CPU 0:
[  598.841977] swapper/0       R  running task        0     0      0 0x00000022
[  598.849023] Call trace:
[  598.851476]  __switch_to+0x98/0xb0
[  598.854870]            (null)

This can be prevented by doing a dummy read of the RX data register.

This issue affects both HSCIF and SCIF ports. Reported for R-Car H3 ES2.0;
reproduced and fixed on H3 ES1.1. Probably affects other R-Car platforms
as well.

Reported-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Signed-off-by: Ulrich Hecht <ulrich.hecht+renesas@gmail.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Tested-by: Nguyen Viet Dung <dung.nguyen.aj@renesas.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
serial: sh-sci: Fix panic when serial console and DMA are enabled 2017-08-26T01:14:24+00:00 Takatoshi Akiyama takatoshi.akiyama.kj@ps.hitachi-solutions.com 2017-02-27T06:56:31+00:00 e9ef18fabda70d46ece72c6b4689d9aaf911a4f6 commit 3c9101766b502a0163d1d437fada5801cf616be2 upstream. This patch fixes an issue that kernel panic happens when DMA is enabled and we press enter key while the kernel booting on the serial console. * An interrupt may occur after sci_request_irq(). * DMA transfer area is initialized by setup_timer() in sci_request_dma() and used in interrupt. If an interrupt occurred between sci_request_irq() and setup_timer() in sci_request_dma(), DMA transfer area has not been initialized yet. So, this patch changes the order of sci_request_irq() and sci_request_dma(). Fixes: 73a19e4c0301 ("serial: sh-sci: Add DMA support.") Signed-off-by: Takatoshi Akiyama <takatoshi.akiyama.kj@ps.hitachi-solutions.com> [Shimoda changes the commit log] Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> 
commit 3c9101766b502a0163d1d437fada5801cf616be2 upstream.

This patch fixes an issue that kernel panic happens when DMA is enabled
and we press enter key while the kernel booting on the serial console.

* An interrupt may occur after sci_request_irq().
* DMA transfer area is initialized by setup_timer() in sci_request_dma()
  and used in interrupt.

If an interrupt occurred between sci_request_irq() and setup_timer() in
sci_request_dma(), DMA transfer area has not been initialized yet.
So, this patch changes the order of sci_request_irq() and
sci_request_dma().

Fixes: 73a19e4c0301 ("serial: sh-sci: Add DMA support.")
Signed-off-by: Takatoshi Akiyama <takatoshi.akiyama.kj@ps.hitachi-solutions.com>
[Shimoda changes the commit log]
Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
serial: sh-sci: Remove cpufreq notifier to fix crash/deadlock 2016-04-30T22:06:11+00:00 Geert Uytterhoeven geert+renesas@glider.be 2016-04-04T14:36:27+00:00 13ead617451aac3dd55daf2fc776e58b991d3de0 commit ff1cab374ad98f4b9f408525ca9c08992b4ed784 upstream. The BSP team noticed that there is spin/mutex lock issue on sh-sci when CPUFREQ is used. The issue is that the notifier function may call mutex_lock() while the spinlock is held, which can lead to a BUG(). This may happen if CPUFREQ is changed while another CPU calls clk_get_rate(). Taking the spinlock was added to the notifier function in commit e552de2413edad1a ("sh-sci: add platform device private data"), to protect the list of serial ports against modification during traversal. At that time the Common Clock Framework didn't exist yet, and clk_get_rate() just returned clk->rate without taking a mutex. Note that since commit d535a2305facf9b4 ("serial: sh-sci: Require a device per port mapping."), there's no longer a list of serial ports to traverse, and taking the spinlock became superfluous. To fix the issue, just remove the cpufreq notifier: 1. The notifier doesn't work correctly: all it does is update the stored clock rate; it does not update the divider in the hardware. The divider will only be updated when calling sci_set_termios(). I believe this was broken back in 2004, when the old drivers/char/sh-sci.c driver (where the notifier did update the divider) was replaced by drivers/serial/sh-sci.c (where the notifier just updated port->uartclk). Cfr. full-history-linux commits 6f8deaef2e9675d9 ("[PATCH] sh: port sh-sci driver to the new API") and 3f73fe878dc9210a ("[PATCH] Remove old sh-sci driver"). 2. On modern SoCs, the sh-sci parent clock rate is no longer related to the CPU clock rate anyway, so using a cpufreq notifier is futile. Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> 
commit ff1cab374ad98f4b9f408525ca9c08992b4ed784 upstream.

The BSP team noticed that there is spin/mutex lock issue on sh-sci when
CPUFREQ is used.  The issue is that the notifier function may call
mutex_lock() while the spinlock is held, which can lead to a BUG().
This may happen if CPUFREQ is changed while another CPU calls
clk_get_rate().

Taking the spinlock was added to the notifier function in commit
e552de2413edad1a ("sh-sci: add platform device private data"), to
protect the list of serial ports against modification during traversal.
At that time the Common Clock Framework didn't exist yet, and
clk_get_rate() just returned clk->rate without taking a mutex.
Note that since commit d535a2305facf9b4 ("serial: sh-sci: Require a
device per port mapping."), there's no longer a list of serial ports to
traverse, and taking the spinlock became superfluous.

To fix the issue, just remove the cpufreq notifier:
  1. The notifier doesn't work correctly: all it does is update the
     stored clock rate; it does not update the divider in the hardware.
     The divider will only be updated when calling sci_set_termios().
     I believe this was broken back in 2004, when the old
     drivers/char/sh-sci.c driver (where the notifier did update the
     divider) was replaced by drivers/serial/sh-sci.c (where the
     notifier just updated port->uartclk).
     Cfr. full-history-linux commits 6f8deaef2e9675d9 ("[PATCH] sh: port
     sh-sci driver to the new API") and 3f73fe878dc9210a ("[PATCH]
     Remove old sh-sci driver").
  2. On modern SoCs, the sh-sci parent clock rate is no longer related
     to the CPU clock rate anyway, so using a cpufreq notifier is
     futile.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Merge tag 'tty-3.15-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty 2014-04-01T23:55:57+00:00 Linus Torvalds torvalds@linux-foundation.org 2014-04-01T23:55:57+00:00 cb1595563880a81dab6eab9a5ecb4520d2e76077 Pull tty/serial driver update from Greg KH: "Here's the big tty/serial driver update for 3.15-rc1. Nothing major, a number of serial driver updates and a few tty core fixes as well. All have been in linux-next for a while" * tag 'tty-3.15-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty: (71 commits) tty/serial: omap: empty the RX FIFO at the end of half-duplex TX tty/serial: omap: fix RX interrupt enable/disable in half-duplex TX serial: sh-sci: Neaten dev_<level> uses serial: sh-sci: Replace hardcoded 3 by UART_PM_STATE_OFF serial: sh-sci: Add more register documentation serial: sh-sci: Remove useless casts serial: sh-sci: Replace printk() by pr_*() serial_core: Avoid NULL pointer dereference in uart_close() serial_core: Get a reference for port->tty in uart_remove_one_port() serial: clps711x: Give a chance to perform useful tasks during wait loop serial_core: Grammar s/ports/port's/ serial_core: Spelling s/contro/control/ serial: efm32: properly namespace location property serial: max310x: Add missing #include <linux/uaccess.h> synclink: fix info leak in ioctl serial: 8250: Clean up the locking for -rt serial: 8250_pci: change BayTrail default uartclk serial: 8250_pci: more BayTrail error-free bauds serial: sh-sci: Add missing call to uart_remove_one_port() in failure path serial_core: Unregister console in uart_remove_one_port() ... 
Pull tty/serial driver update from Greg KH:
 "Here's the big tty/serial driver update for 3.15-rc1.

  Nothing major, a number of serial driver updates and a few tty core
  fixes as well.

  All have been in linux-next for a while"

* tag 'tty-3.15-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty: (71 commits)
  tty/serial: omap: empty the RX FIFO at the end of half-duplex TX
  tty/serial: omap: fix RX interrupt enable/disable in half-duplex TX
  serial: sh-sci: Neaten dev_<level> uses
  serial: sh-sci: Replace hardcoded 3 by UART_PM_STATE_OFF
  serial: sh-sci: Add more register documentation
  serial: sh-sci: Remove useless casts
  serial: sh-sci: Replace printk() by pr_*()
  serial_core: Avoid NULL pointer dereference in uart_close()
  serial_core: Get a reference for port->tty in uart_remove_one_port()
  serial: clps711x: Give a chance to perform useful tasks during wait loop
  serial_core: Grammar s/ports/port's/
  serial_core: Spelling s/contro/control/
  serial: efm32: properly namespace location property
  serial: max310x: Add missing #include <linux/uaccess.h>
  synclink: fix info leak in ioctl
  serial: 8250: Clean up the locking for -rt
  serial: 8250_pci: change BayTrail default uartclk
  serial: 8250_pci: more BayTrail error-free bauds
  serial: sh-sci: Add missing call to uart_remove_one_port() in failure path
  serial_core: Unregister console in uart_remove_one_port()
  ...
cpufreq: remove unused notifier: CPUFREQ_{SUSPENDCHANGE|RESUMECHANGE} 2014-03-19T13:10:24+00:00 Viresh Kumar viresh.kumar@linaro.org 2014-03-19T05:54:58+00:00 0b443ead714f0cba797a7f2476dd756f22b5421e Two cpufreq notifiers CPUFREQ_RESUMECHANGE and CPUFREQ_SUSPENDCHANGE have not been used for some time, so remove them to clean up code a bit. Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Reviewed-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com> [rjw: Changelog] Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> 
Two cpufreq notifiers CPUFREQ_RESUMECHANGE and CPUFREQ_SUSPENDCHANGE have
not been used for some time, so remove them to clean up code a bit.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Reviewed-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
[rjw: Changelog]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
serial: sh-sci: Neaten dev_<level> uses 2014-03-17T23:20:49+00:00 Joe Perches joe@perches.com 2014-03-11T17:10:46+00:00 9b971cd206c019fc6aeeb7e04136a49f9312df4a Add missing newlines and coalesce formats. Realign arguments. Signed-off-by: Joe Perches <joe@perches.com> Acked-by: Geert Uytterhoeven <geert@linux-m68k.org> Acked-by: Simon Horman <horms+renesas@verge.net.au> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
Add missing newlines and coalesce formats.
Realign arguments.

Signed-off-by: Joe Perches <joe@perches.com>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Acked-by: Simon Horman <horms+renesas@verge.net.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
serial: sh-sci: Replace hardcoded 3 by UART_PM_STATE_OFF 2014-03-17T23:20:49+00:00 Geert Uytterhoeven geert+renesas@linux-m68k.org 2014-03-11T10:11:20+00:00 d3dfe5d9b4c8b3156b28f99f7a4a59ad8be09b15 Signed-off-by: Geert Uytterhoeven <geert+renesas@linux-m68k.org> Acked-by: Simon Horman <horms@verge.net.au> Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
Signed-off-by: Geert Uytterhoeven <geert+renesas@linux-m68k.org>
Acked-by: Simon Horman <horms@verge.net.au>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
serial: sh-sci: Add more register documentation 2014-03-17T23:20:49+00:00 Geert Uytterhoeven geert+renesas@linux-m68k.org 2014-03-11T10:11:19+00:00 26de4f1b2fb45e53a9e8f4f913b9cdf6c294070b Signed-off-by: Geert Uytterhoeven <geert+renesas@linux-m68k.org> Acked-by: Simon Horman <horms@verge.net.au> Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
Signed-off-by: Geert Uytterhoeven <geert+renesas@linux-m68k.org>
Acked-by: Simon Horman <horms@verge.net.au>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
serial: sh-sci: Remove useless casts 2014-03-17T23:20:49+00:00 Geert Uytterhoeven geert+renesas@linux-m68k.org 2014-03-11T10:11:18+00:00 ff43da00e0d407cd8e7faaf2ac150001d29827e4 Signed-off-by: Geert Uytterhoeven <geert+renesas@linux-m68k.org> Acked-by: Simon Horman <horms@verge.net.au> Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
Signed-off-by: Geert Uytterhoeven <geert+renesas@linux-m68k.org>
Acked-by: Simon Horman <horms@verge.net.au>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
serial: sh-sci: Replace printk() by pr_*() 2014-03-17T23:20:49+00:00 Geert Uytterhoeven geert+renesas@linux-m68k.org 2014-03-11T10:11:17+00:00 6c13d5d27c5ecd7a2ce7c104c7726b0d7aa7d7b5 Make banner const while we're at it Signed-off-by: Geert Uytterhoeven <geert+renesas@linux-m68k.org> Acked-by: Simon Horman <horms@verge.net.au> Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
Make banner const while we're at it

Signed-off-by: Geert Uytterhoeven <geert+renesas@linux-m68k.org>
Acked-by: Simon Horman <horms@verge.net.au>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>