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2013-04-09tty: Fix race condition if flushing tty flip buffersPeter Hurley1-12/+10
As Ilya Zykov identified in his patch 'PROBLEM: Race condition in tty buffer's function flush_to_ldisc()', a race condition exists which allows a parallel flush_to_ldisc() to flush and free the tty flip buffers while those buffers are in-use. For example, CPU 0 | CPU 1 | CPU 2 | flush_to_ldisc() | | grab spin lock | tty_buffer_flush() | | flush_to_ldisc() wait for spin lock | | wait for spin lock | if (!test_and_set_bit(TTYP_FLUSHING)) | | while (next flip buffer) | | ... | | drop spin lock | grab spin lock | | if (test_bit(TTYP_FLUSHING)) | | set_bit(TTYP_FLUSHPENDING) | receive_buf() | drop spin lock | | | | grab spin lock | | if (!test_and_set_bit(TTYP_FLUSHING)) | | if (test_bit(TTYP_FLUSHPENDING)) | | __tty_buffer_flush() CPU 2 has just flushed and freed all tty flip buffers while CPU 1 is transferring data from the head flip buffer. The original patch was rejected under the assumption that parallel flush_to_ldisc() was not possible. Because of necessary changes to the workqueue api, work items can execute in parallel on SMP. This patch differs slightly from the original patch by testing for a pending flush _after_ each receive_buf(), since TTYP_FLUSHPENDING can only be set while the lock is dropped around receive_buf(). Reported-by: Ilya Zykov <linux@izyk.ru> Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Acked-by: Ilya Zykov <linux@izyk.ru> Cc: Jiri Slaby <jslaby@suse.cz> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-04-09procfs: new helper - PDE_DATA(inode)Al Viro1-1/+1
The only part of proc_dir_entry the code outside of fs/proc really cares about is PDE(inode)->data. Provide a helper for that; static inline for now, eventually will be moved to fs/proc, along with the knowledge of struct proc_dir_entry layout. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-04-08tty: mxser: fix cycle termination condition in mxser_probe() and mxser_module_init()Alexey Khoroshilov1-4/+4
There is a bug in resources deallocation code in mxser_probe() and mxser_module_init(). As soon as variable 'i' is unsigned int, cycle termination condition i >= 0 is always true. The patch fixes the issue. Signed-off-by: Alexey Khoroshilov <khoroshilov@ispras.ru> Acked-by: Jiri Slaby <jslaby@suse.cz> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-04-08Revert "tty/8250_pnp: serial port detection regression since v3.7"Sean Young1-7/+5
This reverts commit 77e372a3d82e5e4878ce1962207edd766773cc76. Checking for disabled resources board breaks detection pnp on another board "AMI UEFI implementation (Version: 0406 Release Date: 06/06/2012)". I'm working with the reporter of the original bug to write and test a better fix. https://bugzilla.redhat.com/show_bug.cgi?id=928246 Signed-off-by: Sean Young <sean@mess.org> Cc: stable <stable@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-04-05serial: max3100: use spi_get_drvdata() and spi_set_drvdata()Jingoo Han1-2/+2
Use the wrapper functions for getting and setting the driver data using spi_device instead of using dev_{get|set}_drvdata with &spi->dev, so we can directly pass a struct spi_device. Signed-off-by: Jingoo Han <jg1.han@samsung.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-04-04serial: mxs-auart: move to use generic DMA helperShawn Guo1-48/+4
With the generic DMA device tree helper supported by mxs-dma driver, client devices only need to call dma_request_slave_channel() for requesting a DMA channel from dmaengine. Signed-off-by: Shawn Guo <shawn.guo@linaro.org> Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Reviewed-by: Arnd Bergmann <arnd@arndb.de>
2013-04-03OMAP/serial: Revert bad fix of Rx FIFO threshold granularityAlexey Pelykh1-0/+11
Partially reverts 1776fd059c40907297d6c26c51876575d63fd9e2 that introduced regression reported by Paul Walmsley. This commit restores setting granularity in SCR register and adds note about comments below being inconsistent with actual code. Signed-off-by: Alexey Pelykh <alexey.pelykh@gmail.com> Tested-by: Paul Walmsley <paul@pwsan.com> Cc: Kevin Hilman <khilman@linaro.org> Cc: Felipe Balbi <balbi@ti.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-04-03amba-pl011: fix build error if CONFIG_DMA_ENGINE is not enabledChanho Min1-0/+4
Following patch will fix build error if CONFIG_DMA_ENGINE is unset. Reported-by: Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by: Chanho Min <chanho.min@lge.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-04-01Input: sysrq - supplement reset sequence with timeout functionalityMathieu J. Poirier1-13/+40
Some devices have too few buttons, which it makes it hard to have a reset combo that won't trigger automatically. As such a timeout functionality that requires the combination to be held for a given amount of time before triggering is introduced. If a key combo is recognized and held for a 'timeout' amount of time, the system triggers a reset. If the timeout value is omitted the driver simply ignores the functionality. Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org> Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
2013-04-01Merge 3.9-rc5 into tty-nextGreg Kroah-Hartman8-26/+58
We need the fixes here as well. Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-04-01Merge v3.9-rc5 into char-misc-nextGreg Kroah-Hartman7-14/+49
This picks up the fixes in 3.9-rc5 that we need here. Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-03-29ARM: PL011: Add support for Rx DMA buffer polling.Chanho Min1-19/+138
In DMA support, The received data is not pushed to tty until the DMA buffer is filled. But some megabyte rate chips such as BT expect fast response and data should be pushed immediately. In order to fix this issue, We suggest the use of the timer for polling DMA buffer. In our test, no data loss occurred at high-baudrate as compared with interrupt- driven (We tested with 3Mbps). We changes: - We add timer for polling. If we set poll_timer to 10, every 10ms, timer handler checks the residue in the dma buffer and transfer data to the tty. Also, last_residue is updated for the next polling. - poll_timeout is used to prevent the timer's system cost. If poll_timeout is set to 3000 and no data is received in 3 seconds, we inactivate poll timer and driver falls back to interrupt-driven. When data is received again in FIFO and UART irq is occurred, we switch back to DMA mode and start polling. - We use consistent DMA mappings to avoid from the frequent cache operation of the timer function for default. - pl011_dma_rx_chars is modified. the pending size is recalculated because data can be taken by polling. - the polling time is adjusted if dma rx poll is enabled but no rate is specified. Ideal polling interval to push 1 character at every interval is the reciprocal of 'baud rate / 10 line bits per character / 1000 ms per sec'. But It is very aggressive to system. Experimentally, '10000000 / baud' is suitable to receive dozens of characters. the poll rate can be specified statically by dma_rx_poll_rate of the platform data as well. Changes compared to v1: - Use of consistent DMA mappings. - Added dma_rx_poll_rate in platform data to specify the polling interval. - Added dma_rx_poll_timeout in platform data to specify the polling timeout. Changes compared to v2: - Use of consistent DMA mappings for default. - Added dma_rx_poll_enable in platform data to adjust the polling time according to the baud rate. - remove unnecessary lock from the polling function. Signed-off-by: Chanho Min <chanho.min@lge.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-03-28serial: 8250_dw: add support for clk apiEmilio López1-9/+24
This commit implements support for using the clk api; this lets us use the "clocks" property with device tree, instead of having to use clock-frequency. Signed-off-by: Emilio López <emilio@elopez.com.ar> Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com> Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-03-28serial: samsung: Avoid waiting forever for TX readyMichael Spang1-3/+19
The no_console_suspend option allows the console to write to the UART during early resume, before the serial port itself is resumed. Such writes hang indefinitely waiting for TX ready. This adds a check to the console putchar function to drop characters instead of hanging if the port hasn't been initialized. That way, we can use no_console_suspend without risk of hanging. Signed-off-by: Michael Spang <spang@chromium.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-03-28serial: samsung: Restore IRQ mask during noirq resumeMichael Spang1-0/+20
This closes a window where the system may hang in resume as soon as the UART interrupt is enabled and before the mask is restored. The hang occurs because the driver can't handle IRQs it thinks are masked. Signed-off-by: Michael Spang <spang@chromium.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-03-28tty: serial: samsung: Disable interrupts in a suspend-friendly wayTomasz Figa1-0/+4
Since the interrupt mask register is not preserved across system suspend and it defaults to all interrupts enabled, it is not enough to disable UART interrupt. This patch adds free_irq to port shutdown and mask setting to port startup to handle IRQ disabling in a suspend-friendly way. In addition, a bug caused by multiple request_irq calls in port startup callback is fixed. Signed-off-by: Tomasz Figa <t.figa@samsung.com> Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-03-28Merge tag 'tty-3.9-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/ttyLinus Torvalds6-12/+45
Pull TTY/serial fixes from Greg Kroah-Hartman: "Here are some tty/serial driver fixes for 3.9. The big thing here is the fix for the huge mess we caused renaming the 8250 driver accidentally in the 3.7 kernel release, without realizing that there were users of the module options that suddenly broke. This is now resolved, and, to top the injury off, we have a backwards- compatible option for those users who got used to the new name since 3.7. Ugh, sorry about that. Other than that, some other minor fixes for issues that have been reported by users." * tag 'tty-3.9-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty: Xilinx: ARM: UART: clear pending irqs before enabling irqs TTY: 8250, deprecated 8250_core.* options TTY: 8250, revert module name change serial: 8250_pci: Add WCH CH352 quirk to avoid Xscale detection tty: atmel_serial_probe(): index of atmel_ports[] fix
2013-03-28serial: 8250: Make SERIAL_8250_RUNTIME_UARTS work correctlyKarthik Manamcheri1-7/+7
Consider a situation where I have an ARM based system and therefore no legacy ports. Say, I have two memory-mapped ports. I use device tree to describe the ports. What would be the config options I set so that I get only the two ports in my system? I do not want legacy ports being created automatically and I want it to be flexible enough that it creates the devices based only on the device tree. I expected setting SERIAL_8250_RUNTIME_UARTS = 0 to work because the description said, "Set this to the maximum number of serial ports you want the kernel to register at boot time." Unfortunately, even though SERIAL_8250_NR_UARTS was set to the default value of 4, I did not get any device nodes (because SERIAL_8250_RUNTIME_UARTS was 0). This is what this change is addressing. SERIAL_8250_NR_UARTS controls the maximum number of ports you can support. SERIAL_8250_RUNTIME_UARTS specifies the number of ports you want to create automatically for legacy ports at boot time. All other ports will be created when serial8250_register_port is called (and if does not exceed the total number of supported ports as specified by SERIAL_8250_NR_UARTS). Signed-off-by: Karthik Manamcheri <karthik.manamcheri@ni.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-03-26Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfsLinus Torvalds1-2/+4
Pull vfs fixes from Al Viro: "stable fodder; assorted deadlock fixes" * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: vt: synchronize_rcu() under spinlock is not nice... Nest rename_lock inside vfsmount_lock Don't bother with redoing rw_verify_area() from default_file_splice_from()
2013-03-26vt: synchronize_rcu() under spinlock is not nice...Al Viro1-2/+4
vcs_poll_data_free() calls unregister_vt_notifier(), which calls atomic_notifier_chain_unregister(), which calls synchronize_rcu(). Do it *after* we'd dropped ->f_lock. Cc: stable@vger.kernel.org (all kernels since 2.6.37) Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-03-26Merge tag 'arizona-extcon-asoc' of git://git.kernel.org/pub/scm/linux/kernel/git/broonie/misc into char-misc-nextGreg Kroah-Hartman10-44/+93
Mark writes: ASoC/extcon: arizona: Fix interaction between HPDET and headphone outputs This patch series covers both ASoC and extcon subsystems and fixes an interaction between the HPDET function and the headphone outputs - we really shouldn't run HPDET while the headphone is active. The first patch is a refactoring to make the extcon side easier.
2013-03-25serial: 8250: remove a few lines of dead codePaul Bolle1-7/+0
Support for the WindRiver SBC8560 board was removed in v3.6. But there are still a few lines depending on its obsolete Kconfig macro. Remove these now. Signed-off-by: Paul Bolle <pebolle@tiscali.nl> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-03-25serial: of_serial: Handle auto-flow-control propertyHeikki Krogerus1-3/+10
Automatic Flow Control capability is not tied to this property. This is only one way of detecting it. The property is limited to be used only with 8250 driver. Signed-off-by: Heikki Krogerus <heikki.krogerus@linux.intel.com> Acked-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-03-25Xilinx: ARM: UART: clear pending irqs before enabling irqsJohn Linn1-0/+2
The Boot ROM has an issue which will cause the driver to lock up as pending irqs are not being cleared. With them cleared it prevents that issue. This patch is needed for the current (3.9-rc3) mainline kernel. I guess it went unnoticed, because it was only tested with u-boot up until now. And u-boot maybe handles this. [s.trumtrar@pengutronix.de: cherry-picked from linux-xlnx.git] Signed-off-by: Steffen Trumtrar <s.trumtrar@pengutronix.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-03-25TTY: 8250, deprecated 8250_core.* optionsJiri Slaby2-0/+19
They were introduced by mistake in 3.7. Let's deprecate them now. For the reasons, see the text in Kconfig below. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Cc: Josh Boyer <jwboyer@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-03-25TTY: 8250, revert module name changeJiri Slaby2-6/+6
In 3.7 the 8250 module name was changed unintentionally from 8250 to 8250_core by commit 835d844d1a28efba81d5aca7385e24c29d3a6db2 (8250_pnp: do pnp probe before legacy probe). We then had to re-introduce the old module options to ensure the old good 8250.nr_uart & co. still work. This can be done only by a very dirty hack and we did it in f2b8dfd9e480c3db3bad0c25c590a5d11b31f4ef (serial: 8250: Keep 8250.<xxxx> module options functional after driver rename). That is so damn ugly so that I decided to revert to the old module name and deprecate the new 8250_core options present in 3.7 and 3.8 only. The deprecation will happen in the following patch. Note that this patch changes the hack above to support "8250_core.*", because we now have "8250.*" natively. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Cc: Josh Boyer <jwboyer@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-03-25tty: tty_vhangup_session can be staticChanglong Xie1-1/+1
Reported-by: Fengguang Wu <fengguang.wu@intel.com> Acked-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-03-25serial: xilinx_uartps: remove superfluous IDR writeSteffen Trumtrar1-3/+0
The datesheet clearly states, that writing low bits to the XUARTPS_IDR register have no effect. Remove the write. Signed-off-by: Steffen Trumtrar <s.trumtrar@pengutronix.de> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-03-25serial: sh-sci: remove obsolete Kconfig macrosPaul Bolle1-2/+0
Support for SH7367 and SH7377 got removed in v3.8. Now remove their last Kconfig macros. Signed-off-by: Paul Bolle <pebolle@tiscali.nl> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-03-25serial: of_serial: Handle fifo-size propertyHeikki Krogerus1-0/+4
This will reduce the need for extra types in 8250.c just in case the fifo size differs from the standard. Signed-off-by: Heikki Krogerus <heikki.krogerus@linux.intel.com> Acked-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-03-25serial: 8250: Allow probe drivers to ignore tx_loadszHeikki Krogerus1-0/+4
In most cases the tx_loadsz is the same as fifosize. This will store the fifosize in it if it was not separately delivered from the driver. Signed-off-by: Heikki Krogerus <heikki.krogerus@linux.intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-03-21Merge 3.9-rc3 into tty-nextGreg Kroah-Hartman9-32/+84
2013-03-19Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/sparcLinus Torvalds1-12/+9
Pull sparc fixes from David Miller: "Just some minor fixups, a sunsu console setup panic cure, and recognition of a Fujitsu sun4v cpu." * git://git.kernel.org/pub/scm/linux/kernel/git/davem/sparc: sparc: remove unused "config BITS" sparc: delete "if !ULTRA_HAS_POPULATION_COUNT" sparc64: correctly recognize SPARC64-X chips sparc,leon: fix GRPCI2 device0 PCI config space access sunsu: Fix panic in case of nonexistent port at "console=ttySY" cmdline option
2013-03-18driver: tty: vt: remove cast for kmalloc return valueZhang Yanfei1-2/+1
remove cast for kmalloc return value. Signed-off-by: Zhang Yanfei <zhangyanfei@cn.fujitsu.com> Cc: Jiri Slaby <jslaby@suse.cz> Cc: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-03-18driver: tty: serial: remove cast for kzalloc return valueZhang Yanfei1-2/+1
remove cast for kzalloc return value. Signed-off-by: Zhang Yanfei <zhangyanfei@cn.fujitsu.com> Cc: Jiri Slaby <jslaby@suse.cz> Cc: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-03-18TTY: serial, stop accessing potential NULLsJiri Slaby2-2/+2
The following commits: * 6732c8bb8671acbdac6cdc93dd72ddd581dd5e25 (TTY: switch tty_schedule_flip) * 2e124b4a390ca85325fae75764bef92f0547fa25 (TTY: switch tty_flip_buffer_push) * 05c7cd39907184328f48d3e7899f9cdd653ad336 (TTY: switch tty_insert_flip_string) * 92a19f9cec9a80ad93c06e115822deb729e2c6ad (TTY: switch tty_insert_flip_char) * 227434f8986c3827a1faedd1feb437acd6285315 (TTY: switch tty_buffer_request_room to tty_port) introduced a potential NULL dereference to some drivers. In particular, when the device is used as a console, incoming bytes can kill the box. This is caused by removed checks for TTY against NULL. It happened because it was unclear to me why the checks were there. I assumed them superfluous because the interrupts were unbound or otherwise stopped. But this is not the case for consoles for these drivers, as was pointed out by David Miller. Now, this patch re-introduces the checks (at this point we check port->state, not the tty proper, as we do not care about tty pointers anymore). For both of the drivers, we place the check below the handling of break signal so that sysrq can actually work. (One needs to issue a break and then sysrq key within the following 5 seconds.) We do not change sc26xx, sunhv, and sunsu here because they behave the same as before. People having that hardware should fix the driver eventually, however. They always could unconditionally dereference tty in receive_chars, port->state in uart_handle_dcd_change, and up->port.state->port.tty. There is perhaps more to fix in all those drivers, but they are at least in a state they were before. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Cc: "David S. Miller" <davem@davemloft.net> Cc: Grant Likely <grant.likely@secretlab.ca> Cc: Rob Herring <rob.herring@calxeda.com> Cc: sparclinux@vger.kernel.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-03-18tty: Fix recursive deadlock in tty_perform_flush()Peter Hurley1-9/+19
tty_perform_flush() can deadlock when called while holding a line discipline reference. By definition, all ldisc drivers hold a ldisc reference, so calls originating from ldisc drivers must not block for a ldisc reference. The deadlock can occur when: CPU 0 | CPU 1 | tty_ldisc_ref(tty) | .... | <line discipline halted> tty_ldisc_ref_wait(tty) | | CPU 0 cannot progess because it cannot obtain an ldisc reference with the line discipline has been halted (thus no new references are granted). CPU 1 cannot progress because an outstanding ldisc reference has not been released. An in-tree call-tree audit of tty_perform_flush() [1] shows 5 ldisc drivers calling tty_perform_flush() indirectly via n_tty_ioctl_helper() and 2 ldisc drivers calling directly. A single tty driver safely uses the function. [1] Recursive usage: /* These functions are line discipline ioctls and thus * recursive wrt line discipline references */ tty_perform_flush() - ./drivers/tty/tty_ioctl.c n_tty_ioctl_helper() hci_uart_tty_ioctl(default) - drivers/bluetooth/hci_ldisc.c (N_HCI) n_hdlc_tty_ioctl(default) - drivers/tty/n_hdlc.c (N_HDLC) gsmld_ioctl(default) - drivers/tty/n_gsm.c (N_GSM0710) n_tty_ioctl(default) - drivers/tty/n_tty.c (N_TTY) gigaset_tty_ioctl(default) - drivers/isdn/gigaset/ser-gigaset.c (N_GIGASET_M101) ppp_synctty_ioctl(TCFLSH) - drivers/net/ppp/pps_synctty.c ppp_asynctty_ioctl(TCFLSH) - drivers/net/ppp/ppp_async.c Non-recursive use: tty_perform_flush() - drivers/tty/tty_ioctl.c ipw_ioctl(TCFLSH) - drivers/tty/ipwireless/tty.c /* This function is a tty i/o ioctl method, which * is invoked by tty_ioctl() */ Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-03-18tty: Remove redundant tty_wait_until_sent()Peter Hurley1-9/+0
tty_ioctl() already waits until sent. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-03-18tty: Locate get/put ldisc functions togetherPeter Hurley1-23/+23
Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-03-18tty: Fold one-line assign function into callersPeter Hurley1-25/+6
Now that tty_ldisc_assign() is a one-line file-scoped function, remove it and perform the simple assignment at its call sites. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-03-18tty: Document unsafe ldisc reference acquirePeter Hurley1-9/+5
Merge get_ldisc() into its only call site. Note how, after merging, the unsafe acquire of an ldisc reference is obvious. CPU 0 in tty_ldisc_try() | CPU 1 in tty_ldisc_halt() | test_bit(TTY_LDISC, &tty_flags) | if (true) | clear_bit(TTY_LDISC, &tty_flags) tty->ldisc != 0? | atomic_read(&tty->ldisc->users) if (true) | ret_val == 1? atomic_inc(&tty->ldisc->users) | if (false) | wait | <goes on assuming safe ldisc use> | <doesn't wait - proceeds w/ close> | The spin lock in tty_ldisc_try() does nothing wrt synchronizing the ldisc halt since it's not acquired as part of halting. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-03-18tty: Separate release semantics of ldisc referencePeter Hurley1-34/+35
tty_ldisc_ref()/tty_ldisc_unref() have usage semantics equivalent to down_read_trylock()/up_read(). Only callers of tty_ldisc_put() are performing the additional operations necessary for proper ldisc teardown, and then only after ensuring no outstanding 'read lock' remains. Thus, tty_ldisc_unref() should never be the last reference; WARN if it is. Conversely, tty_ldisc_put() should never be destructing if the use count != 1. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-03-18tty: Don't protect atomic operation with mutexPeter Hurley1-2/+0
test_bit() is already atomic; drop mutex lock/unlock. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-03-18tty: Add ldisc hangup debug messagesPeter Hurley1-0/+19
Expected typical debug log: [ 582.721965] tty_open: opening pts3... [ 582.721970] tty_open: opening pts3... [ 582.721977] tty_release: pts3 (tty count=3)... [ 582.721980] tty_release: ptm3 (tty count=1)... [ 582.722015] pts3 vhangup... [ 582.722020] tty_ldisc_hangup: pts3: closing ldisc: ffff88007a920540 [ 582.724128] tty_release: pts3 (tty count=2)... [ 582.724217] tty_ldisc_hangup: pts3: re-opened ldisc: ffff88007a920580 [ 582.724221] tty_release: ptm3: final close [ 582.724234] tty_ldisc_release: ptm3: closing ldisc: ffff88007a920a80 [ 582.724238] tty_ldisc_release: ptm3: ldisc closed [ 582.724241] tty_release: ptm3: freeing structure... [ 582.724741] tty_open: opening pts3... Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-03-18tty: Bracket ldisc release with TTY_DEBUG_HANGUP messagesPeter Hurley1-1/+4
Expected typical log output: [ 2.437211] tty_open: opening pts1... [ 2.443376] tty_open: opening pts5... [ 2.447830] tty_release: ptm0 (tty count=1)... [ 2.447849] pts0 vhangup... [ 2.447865] tty_release: ptm0: final close [ 2.447876] tty_release: ptm0: freeing structure... [ 2.451634] tty_release: tty1 (tty count=1)... [ 2.451638] tty_release: tty1: final close [ 2.451654] tty_release: tty1: freeing structure... [ 2.452505] tty_release: pts5 (tty count=2)... [ 2.453029] tty_open: opening pts0... Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-03-18tty: Fix 'deferred reopen' ldisc commentPeter Hurley1-4/+5
This comment is a victim of code migration from "tty: Fix the ldisc hangup race"; re-parent it. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-03-18tty: Make core responsible for synchronizing its workPeter Hurley2-20/+21
The tty core relies on the ldisc layer for synchronizing destruction of the tty. Instead, the final tty release must wait for any pending tty work to complete prior to tty destruction. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-03-18tty: Complete ownership transfer of flip buffersPeter Hurley3-35/+14
Waiting for buffer work to complete is not required for safely performing changes to the line discipline, once the line discipline is halted. The buffer work routine, flush_to_ldisc(), will be unable to acquire an ldisc ref and all existing references were waited until released (so it can't already have one). Ensure running buffer work which may reference the soon-to-be-gone tty completes and any buffer work running after this point retrieves a NULL tty. Also, ensure all buffer work is cancelled on port destruction. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-03-18tty: Don't reenable already enabled ldiscPeter Hurley2-2/+1
tty_ldisc_hangup() guarantees the ldisc is enabled (or that there is no ldisc). Since __tty_hangup() was the only user, re-define tty_ldisc_enable() in file-scope. Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-03-18n_tty: Fully initialize ldisc before restarting buffer workPeter Hurley1-9/+8
Buffer work may already be pending when the n_tty ldisc is re-opened, eg., when setting the ldisc (via TIOCSETD ioctl) and when hanging up the tty. Since n_tty_set_room() may restart buffer work, first ensure the ldisc is completely initialized. Factor n_tty_set_room() out of reset_buffer_flags() (only 2 callers) and reorganize n_tty_open() to set termios last; buffer work will be restarted there if necessary, after the char_map is properly initialized. Fixes this WARNING: [ 549.561769] ------------[ cut here ]------------ [ 549.598755] WARNING: at drivers/tty/n_tty.c:160 n_tty_set_room+0xff/0x130() [ 549.604058] scheduling buffer work for halted ldisc [ 549.607741] Pid: 9417, comm: trinity-child28 Tainted: G D W 3.7.0-next-20121217-sasha-00023-g8689ef9 #219 [ 549.652580] Call Trace: [ 549.662754] [<ffffffff81c432cf>] ? n_tty_set_room+0xff/0x130 [ 549.665458] [<ffffffff8110cae7>] warn_slowpath_common+0x87/0xb0 [ 549.668257] [<ffffffff8110cb71>] warn_slowpath_fmt+0x41/0x50 [ 549.671007] [<ffffffff81c432cf>] n_tty_set_room+0xff/0x130 [ 549.673268] [<ffffffff81c44597>] reset_buffer_flags+0x137/0x150 [ 549.675607] [<ffffffff81c45b71>] n_tty_open+0x131/0x1c0 [ 549.677699] [<ffffffff81c47824>] tty_ldisc_open.isra.5+0x54/0x70 [ 549.680147] [<ffffffff81c482bf>] tty_ldisc_hangup+0x11f/0x1e0 [ 549.682409] [<ffffffff81c3fa17>] __tty_hangup+0x137/0x440 [ 549.684634] [<ffffffff81c3fd49>] tty_vhangup+0x9/0x10 [ 549.686443] [<ffffffff81c4a42c>] pty_close+0x14c/0x160 [ 549.688446] [<ffffffff81c41225>] tty_release+0xd5/0x490 [ 549.690460] [<ffffffff8127d8a2>] __fput+0x122/0x250 [ 549.692577] [<ffffffff8127d9d9>] ____fput+0x9/0x10 [ 549.694534] [<ffffffff811348c2>] task_work_run+0xb2/0xf0 [ 549.696349] [<ffffffff81113c6d>] do_exit+0x36d/0x580 [ 549.698286] [<ffffffff8107d964>] ? syscall_trace_enter+0x24/0x2e0 [ 549.702729] [<ffffffff81113f4a>] do_group_exit+0x8a/0xc0 [ 549.706775] [<ffffffff81113f92>] sys_exit_group+0x12/0x20 [ 549.711088] [<ffffffff83cfab18>] tracesys+0xe1/0xe6 [ 549.728001] ---[ end trace 73eb41728f11f87e ]--- Reported-by: Sasha Levin <levinsasha928@gmail.com> Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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