linux-stable.git/drivers/tty/serial/sh-sci.c, branch linux-3.2.y Linux kernel stable tree serial: sh-sci: prevent lockup on full TTY buffers 2018-05-31T23:30:19+00:00 Ulrich Hecht ulrich.hecht+renesas@gmail.com 2018-02-15T12:02:27+00:00 1063c9391c430f0059780c55be0874dce91e59d2 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> [bwh: Backported to 3.2: - Use sci_in() - Adjust context] 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>
[bwh: Backported to 3.2:
 - Use sci_in()
 - Adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
serial: sh-sci: Fix panic when serial console and DMA are enabled 2017-08-26T01:13:57+00:00 Takatoshi Akiyama takatoshi.akiyama.kj@ps.hitachi-solutions.com 2017-02-27T06:56:31+00:00 135e5d48d5340a13dde43d38193fb58f661e8d47 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> [bwh: Backported to 3.2: adjust context] 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>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
serial: sh-sci: Remove cpufreq notifier to fix crash/deadlock 2016-04-30T22:05:26+00:00 Geert Uytterhoeven geert+renesas@glider.be 2016-04-04T14:36:25+00:00 6bd428ff0eddf816393f30e0fca877f509affb57 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> [bwh: Backported to 3.2: adjust context] 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>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
serial: sh-sci: fix a race of DMA submit_tx on transfer 2012-04-02T16:53:10+00:00 Yoshii Takashi takashi.yoshii.zj@renesas.com 2012-03-14T07:14:43+00:00 46979bfe3c1c2435f7f8190ff0c0994de3cfc471 commit 49d4bcaddca977fffdea8b0b71f6e5da96dac78e upstream. When DMA is enabled, sh-sci transfer begins with uart_start() sci_start_tx() if (cookie_tx < 0) schedule_work() Then, starts DMA when wq scheduled, -- (A) process_one_work() work_fn_rx() cookie_tx = desc->submit_tx() And finishes when DMA transfer ends, -- (B) sci_dma_tx_complete() async_tx_ack() cookie_tx = -EINVAL (possible another schedule_work()) This A to B sequence is not reentrant, since controlling variables (for example, cookie_tx above) are not queues nor lists. So, they must be invoked as A B A B..., otherwise results in kernel crash. To ensure the sequence, sci_start_tx() seems to test if cookie_tx < 0 (represents "not used") to call schedule_work(). But cookie_tx will not be set (to a cookie, also means "used") until in the middle of work queue scheduled function work_fn_tx(). This gap between the test and set allows the breakage of the sequence under the very frequently call of uart_start(). Another gap between async_tx_ack() and another schedule_work() results in the same issue, too. This patch introduces a new condition "cookie_tx == 0" just to mark it is "busy" and assign it within spin-locked region to fill the gaps. Signed-off-by: Takashi Yoshii <takashi.yoshii.zj@renesas.com> Reviewed-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de> Signed-off-by: Paul Mundt <lethal@linux-sh.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 49d4bcaddca977fffdea8b0b71f6e5da96dac78e upstream.

When DMA is enabled, sh-sci transfer begins with
 uart_start()
  sci_start_tx()
    if (cookie_tx < 0) schedule_work()
Then, starts DMA when wq scheduled, -- (A)
 process_one_work()
  work_fn_rx()
   cookie_tx = desc->submit_tx()
And finishes when DMA transfer ends, -- (B)
 sci_dma_tx_complete()
  async_tx_ack()
  cookie_tx = -EINVAL
  (possible another schedule_work())

This A to B sequence is not reentrant, since controlling variables
(for example, cookie_tx above) are not queues nor lists. So, they
must be invoked as A B A B..., otherwise results in kernel crash.

To ensure the sequence, sci_start_tx() seems to test if cookie_tx < 0
(represents "not used") to call schedule_work().
But cookie_tx will not be set (to a cookie, also means "used") until
in the middle of work queue scheduled function work_fn_tx().

This gap between the test and set allows the breakage of the sequence
under the very frequently call of uart_start().
Another gap between async_tx_ack() and another schedule_work() results
in the same issue, too.

This patch introduces a new condition "cookie_tx == 0" just to mark
it is "busy" and assign it within spin-locked region to fill the gaps.

Signed-off-by: Takashi Yoshii <takashi.yoshii.zj@renesas.com>
Reviewed-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Merge branches 'sh/pm-runtime' and 'common/clkfwk' into sh-fixes-for-linus 2011-11-11T07:16:25+00:00 Paul Mundt lethal@linux-sh.org 2011-11-11T07:16:25+00:00 37bef8f989ed85cdc6cf6fb9c1b1c096179b0708 






Merge branch 'next' of git://git.infradead.org/users/vkoul/slave-dma
2011-11-05T01:02:25+00:00

Linus Torvalds
torvalds@linux-foundation.org

2011-11-05T01:02:25+00:00

fba9569924e06da076cb2ad12474bbd82d69f54d

* 'next' of git://git.infradead.org/users/vkoul/slave-dma: (63 commits)
  dmaengine: mid_dma: mask_peripheral_interrupt only when dmac is idle
  dmaengine/ep93xx_dma: add module.h include
  pch_dma: Reduce wasting memory
  pch_dma: Fix suspend issue
  dma/timberdale: free_irq() on an error path
  dma: shdma: transfer based runtime PM
  dmaengine: shdma: protect against the IRQ handler
  dmaengine i.MX DMA/SDMA: add missing include of linux/module.h
  dmaengine: delete redundant chan_id and chancnt initialization in dma drivers
  dmaengine/amba-pl08x: Check txd->llis_va before freeing dma_pool
  dmaengine/amba-pl08x: Add support for sg len greater than one for slave transfers
  serial: sh-sci: don't filter on DMA device, use only channel ID
  ARM: SAMSUNG: Remove Samsung specific enum type for dma direction
  ASoC: Samsung: Update DMA interface
  spi/s3c64xx: Merge dma control code
  spi/s3c64xx: Add support DMA engine API
  ARM: SAMSUNG: Remove S3C-PL330-DMA driver
  ARM: S5P64X0: Use generic DMA PL330 driver
  ARM: S5PC100: Use generic DMA PL330 driver
  ARM: S5PV210: Use generic DMA PL330 driver
  ...

Fix up fairly trivial conflicts in
 - arch/arm/mach-exynos4/{Kconfig,clock.c}
 - arch/arm/mach-s5p64x0/dma.c





* 'next' of git://git.infradead.org/users/vkoul/slave-dma: (63 commits)
  dmaengine: mid_dma: mask_peripheral_interrupt only when dmac is idle
  dmaengine/ep93xx_dma: add module.h include
  pch_dma: Reduce wasting memory
  pch_dma: Fix suspend issue
  dma/timberdale: free_irq() on an error path
  dma: shdma: transfer based runtime PM
  dmaengine: shdma: protect against the IRQ handler
  dmaengine i.MX DMA/SDMA: add missing include of linux/module.h
  dmaengine: delete redundant chan_id and chancnt initialization in dma drivers
  dmaengine/amba-pl08x: Check txd->llis_va before freeing dma_pool
  dmaengine/amba-pl08x: Add support for sg len greater than one for slave transfers
  serial: sh-sci: don't filter on DMA device, use only channel ID
  ARM: SAMSUNG: Remove Samsung specific enum type for dma direction
  ASoC: Samsung: Update DMA interface
  spi/s3c64xx: Merge dma control code
  spi/s3c64xx: Add support DMA engine API
  ARM: SAMSUNG: Remove S3C-PL330-DMA driver
  ARM: S5P64X0: Use generic DMA PL330 driver
  ARM: S5PC100: Use generic DMA PL330 driver
  ARM: S5PV210: Use generic DMA PL330 driver
  ...

Fix up fairly trivial conflicts in
 - arch/arm/mach-exynos4/{Kconfig,clock.c}
 - arch/arm/mach-s5p64x0/dma.c







serial: sh-sci: Fix up SH-2A SCIF support.
2011-11-04T13:33:30+00:00

Phil Edworthy
phil.edworthy@renesas.com

2011-10-03T14:16:47+00:00

3af1f8a41feab47b232b0c3d3b2322426672480d

This fixes up support for SH-2(A) SCIFs by introducing a new regtype. As
expected, it's close to the SH-4A SCIF with fifodata, but still different
enough to warrant its own type.

Fixes up a number of FIFO overflows and similar for both SH7203/SH7264.

Signed-off-by: Phil Edworthy <phil.edworthy@renesas.com>
Tested-by: Federico Fuga <fuga@studiofuga.com>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>





This fixes up support for SH-2(A) SCIFs by introducing a new regtype. As
expected, it's close to the SH-4A SCIF with fifodata, but still different
enough to warrant its own type.

Fixes up a number of FIFO overflows and similar for both SH7203/SH7264.

Signed-off-by: Phil Edworthy <phil.edworthy@renesas.com>
Tested-by: Federico Fuga <fuga@studiofuga.com>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>







Merge branch 'tty-next' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty
2011-10-26T13:11:09+00:00

Linus Torvalds
torvalds@linux-foundation.org

2011-10-26T13:11:09+00:00

efb8d21b2c6db3497655cc6a033ae8a9883e4063

* 'tty-next' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty: (79 commits)
  TTY: serial_core: Fix crash if DCD drop during suspend
  tty/serial: atmel_serial: bootconsole removed from auto-enumerates
  Revert "TTY: call tty_driver_lookup_tty unconditionally"
  tty/serial: atmel_serial: add device tree support
  tty/serial: atmel_serial: auto-enumerate ports
  tty/serial: atmel_serial: whitespace and braces modifications
  tty/serial: atmel_serial: change platform_data variable name
  tty/serial: RS485 bindings for device tree
  TTY: call tty_driver_lookup_tty unconditionally
  TTY: pty, release tty in all ptmx_open fail paths
  TTY: make tty_add_file non-failing
  TTY: drop driver reference in tty_open fail path
  8250_pci: Fix kernel panic when pch_uart is disabled
  h8300: drivers/serial/Kconfig was moved
  parport_pc: release IO region properly if unsupported ITE887x card is found
  tty: Support compat_ioctl get/set termios_locked
  hvc_console: display printk messages on console.
  TTY: snyclinkmp: forever loop in tx_load_dma_buffer()
  tty/n_gsm: avoid fifo overflow in gsm_dlci_data_output
  tty/n_gsm: fix a bug in gsm_dlci_data_output (adaption = 2 case)
  ...

Fix up Conflicts in:
 - drivers/tty/serial/8250_pci.c
	Trivial conflict with removed duplicate device ID
 - drivers/tty/serial/atmel_serial.c
	Annoying silly conflict between "specify the port num via
	platform_data" and other changes to atmel_console_init





* 'tty-next' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty: (79 commits)
  TTY: serial_core: Fix crash if DCD drop during suspend
  tty/serial: atmel_serial: bootconsole removed from auto-enumerates
  Revert "TTY: call tty_driver_lookup_tty unconditionally"
  tty/serial: atmel_serial: add device tree support
  tty/serial: atmel_serial: auto-enumerate ports
  tty/serial: atmel_serial: whitespace and braces modifications
  tty/serial: atmel_serial: change platform_data variable name
  tty/serial: RS485 bindings for device tree
  TTY: call tty_driver_lookup_tty unconditionally
  TTY: pty, release tty in all ptmx_open fail paths
  TTY: make tty_add_file non-failing
  TTY: drop driver reference in tty_open fail path
  8250_pci: Fix kernel panic when pch_uart is disabled
  h8300: drivers/serial/Kconfig was moved
  parport_pc: release IO region properly if unsupported ITE887x card is found
  tty: Support compat_ioctl get/set termios_locked
  hvc_console: display printk messages on console.
  TTY: snyclinkmp: forever loop in tx_load_dma_buffer()
  tty/n_gsm: avoid fifo overflow in gsm_dlci_data_output
  tty/n_gsm: fix a bug in gsm_dlci_data_output (adaption = 2 case)
  ...

Fix up Conflicts in:
 - drivers/tty/serial/8250_pci.c
	Trivial conflict with removed duplicate device ID
 - drivers/tty/serial/atmel_serial.c
	Annoying silly conflict between "specify the port num via
	platform_data" and other changes to atmel_console_init







TTY: irq: Remove IRQF_DISABLED
2011-09-22T23:08:57+00:00

Yong Zhang
yong.zhang0@gmail.com

2011-09-22T08:59:15+00:00

9cfb5c05fee914cc65d4706801f6bc424082b5f5

Since commit [e58aa3d2: genirq: Run irq handlers with interrupts disabled],
We run all interrupt handlers with interrupts disabled
and we even check and yell when an interrupt handler
returns with interrupts enabled (see commit [b738a50a:
genirq: Warn when handler enables interrupts]).

So now this flag is a NOOP and can be removed.

Signed-off-by: Yong Zhang <yong.zhang0@gmail.com>
Acked-by: Tobias Klauser <tklauser@distanz.ch>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>





Since commit [e58aa3d2: genirq: Run irq handlers with interrupts disabled],
We run all interrupt handlers with interrupts disabled
and we even check and yell when an interrupt handler
returns with interrupts enabled (see commit [b738a50a:
genirq: Warn when handler enables interrupts]).

So now this flag is a NOOP and can be removed.

Signed-off-by: Yong Zhang <yong.zhang0@gmail.com>
Acked-by: Tobias Klauser <tklauser@distanz.ch>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>







serial: sh-sci: don't filter on DMA device, use only channel ID
2011-09-19T03:09:17+00:00

Guennadi Liakhovetski
g.liakhovetski@gmx.de

2011-06-24T11:56:15+00:00

937bb6e4c676fecbfbc1939b942241c3f27bf5d8

On some sh-mobile systems there are more than one DMA controllers, that
can be used for serial ports. Specifying a DMA device in sh-sci platform
data unnecessarily restricts the driver to only use one DMA controller.

Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
[Fixed the trivial conflict in include/linux/serial_sci.h]
Signed-off-by: Vinod Koul <vinod.koul@intel.com>





On some sh-mobile systems there are more than one DMA controllers, that
can be used for serial ports. Specifying a DMA device in sh-sci platform
data unnecessarily restricts the driver to only use one DMA controller.

Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
[Fixed the trivial conflict in include/linux/serial_sci.h]
Signed-off-by: Vinod Koul <vinod.koul@intel.com>