user/sven/linux.git/include/linux/tty.h, branch v3.14.33

tty: Fix low_latency BUG

2014-04-27T00:19:04Z

commit a9c3f68f3cd8d55f809fbdb0c138ed061ea1bd25 upstream. The user-settable knob, low_latency, has been the source of several BUG reports which stem from flush_to_ldisc() running in interrupt context. Since 3.12, which added several sleeping locks (termios_rwsem and buf->lock) to the input processing path, the frequency of these BUG reports has increased. Note that changes in 3.12 did not introduce this regression; sleeping locks were first added to the input processing path with the removal of the BKL from N_TTY in commit a88a69c91256418c5907c2f1f8a0ec0a36f9e6cc, 'n_tty: Fix loss of echoed characters and remove bkl from n_tty' and later in commit 38db89799bdf11625a831c5af33938dcb11908b6, 'tty: throttling race fix'. Since those changes, executing flush_to_ldisc() in interrupt_context (ie, low_latency set), is unsafe. However, since most devices do not validate if the low_latency setting is appropriate for the context (process or interrupt) in which they receive data, some reports are due to misconfiguration. Further, serial dma devices for which dma fails, resort to interrupt receiving as a backup without resetting low_latency. Historically, low_latency was used to force wake-up the reading process rather than wait for the next scheduler tick. The effect was to trim multiple milliseconds of latency from when the process would receive new data. Recent tests [1] have shown that the reading process now receives data with only 10's of microseconds latency without low_latency set. Remove the low_latency rx steering from tty_flip_buffer_push(); however, leave the knob as an optional hint to drivers that can tune their rx fifos and such like. Cleanup stale code comments regarding low_latency. [1] https://lkml.org/lkml/2014/2/20/434 "Yay.. thats an annoying historical pain in the butt gone." -- Alan Cox Reported-by: Beat Bolli Reported-by: Pavel Roskin Acked-by: David Sterba Cc: Grant Edwards Cc: Stanislaw Gruszka Cc: Hal Murray Signed-off-by: Peter Hurley Signed-off-by: Alan Cox Signed-off-by: Greg Kroah-Hartman

Merge tag 'usb-3.14-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb

2014-01-21T00:13:02Z

Pull USB updates from Greg KH: "Here's the big USB pull request for 3.14-rc1 Lots of little things all over the place, and the usual USB gadget updates, and XHCI fixes (some for an issue reported by a lot of people). USB PHY updates as well as chipidea updates and fixes. All of these have been in the linux-next tree with no reported issues" * tag 'usb-3.14-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb: (318 commits) usb: chipidea: udc: using MultO at TD as real mult value for ISO-TX usb: chipidea: need to mask INT_STATUS when write otgsc usb: chipidea: put hw_phymode_configure before ci_usb_phy_init usb: chipidea: Fix Internal error: : 808 [#1] ARM related to STS flag usb: chipidea: imx: set CI_HDRC_IMX28_WRITE_FIX for imx28 usb: chipidea: add freescale imx28 special write register method usb: ehci: add freescale imx28 special write register method usb: core: check for valid id_table when using the RefId feature usb: cdc-wdm: resp_count can be 0 even if WDM_READ is set usb: core: bail out if user gives an unknown RefId when using new_id usb: core: allow a reference device for new_id usb: core: add sanity checks when using bInterfaceClass with new_id USB: image: correct spelling mistake in comment USB: c67x00: correct spelling mistakes in comments usb: delete non-required instances of include usb:hub set hub->change_bits when over-current happens Revert "usb: chipidea: imx: set CI_HDRC_IMX28_WRITE_FIX for imx28" xhci: Set scatter-gather limit to avoid failed block writes. xhci: Avoid infinite loop when sg urb requires too many trbs usb: gadget: remove unused variable in gr_queue_int() ...

tty: Add C_CMSPAR(tty)

2014-01-03T20:32:32Z

Add the missing C_CMSPAR(tty) macro. Signed-off-by: Andrew Lunn Signed-off-by: Johan Hovold Signed-off-by: Greg Kroah-Hartman

tty: Removing the deprecated function tty_vhangup_locked()

2013-12-19T00:59:11Z

The function tty_vhangup_locked() was deprecated, removed it from the tty.h also. Signed-off-by: Liu, Chuansheng Signed-off-by: Greg Kroah-Hartman

tty: Halve flip buffer GFP_ATOMIC memory consumption

2013-12-09T19:09:24Z

tty flip buffers use GFP_ATOMIC allocations for received data which is to be processed by the line discipline. For each byte received, an extra byte is used to indicate the error status of that byte. Instead, if the received data is error-free, encode the entire buffer without status bytes. Signed-off-by: Peter Hurley Signed-off-by: Greg Kroah-Hartman

tty: Rename tty buffer memory_used field

2013-12-09T00:57:38Z

Trim up the memory_used field name to mem_used. Signed-off-by: Peter Hurley Signed-off-by: Greg Kroah-Hartman

tty: Enable configurable tty flip buffer limit

2013-12-09T00:57:38Z

Allow driver to configure its maximum flip buffer memory consumption/limit. This is necessary for very-high speed line rates (in excess of 10MB/sec) because the flip buffers can be saturated before the line discipline has a chance to throttle the input. Signed-off-by: Peter Hurley Signed-off-by: Greg Kroah-Hartman

Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2013-11-12T01:20:12Z

Pull scheduler changes from Ingo Molnar: "The main changes in this cycle are: - (much) improved CONFIG_NUMA_BALANCING support from Mel Gorman, Rik van Riel, Peter Zijlstra et al. Yay! - optimize preemption counter handling: merge the NEED_RESCHED flag into the preempt_count variable, by Peter Zijlstra. - wait.h fixes and code reorganization from Peter Zijlstra - cfs_bandwidth fixes from Ben Segall - SMP load-balancer cleanups from Peter Zijstra - idle balancer improvements from Jason Low - other fixes and cleanups" * 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (129 commits) ftrace, sched: Add TRACE_FLAG_PREEMPT_RESCHED stop_machine: Fix race between stop_two_cpus() and stop_cpus() sched: Remove unnecessary iteration over sched domains to update nr_busy_cpus sched: Fix asymmetric scheduling for POWER7 sched: Move completion code from core.c to completion.c sched: Move wait code from core.c to wait.c sched: Move wait.c into kernel/sched/ sched/wait: Fix __wait_event_interruptible_lock_irq_timeout() sched: Avoid throttle_cfs_rq() racing with period_timer stopping sched: Guarantee new group-entities always have weight sched: Fix hrtimer_cancel()/rq->lock deadlock sched: Fix cfs_bandwidth misuse of hrtimer_expires_remaining sched: Fix race on toggling cfs_bandwidth_used sched: Remove extra put_online_cpus() inside sched_setaffinity() sched/rt: Fix task_tick_rt() comment sched/wait: Fix build breakage sched/wait: Introduce prepare_to_wait_event() sched/wait: Add ___wait_cond_timeout() to wait_event*_timeout() too sched: Remove get_online_cpus() usage sched: Fix race in migrate_swap_stop() ...

sched/wait: Make the __wait_event*() interface more friendly

2013-10-04T08:16:25Z

Change all __wait_event*() implementations to match the corresponding wait_event*() signature for convenience. In particular this does away with the weird 'ret' logic. Since there are __wait_event*() users this requires we update them too. Reviewed-by: Oleg Nesterov Signed-off-by: Peter Zijlstra Link: http://lkml.kernel.org/r/20131002092529.042563462@infradead.org Signed-off-by: Ingo Molnar

sched/wait: Collapse __wait_event_interruptible_tty()

2013-10-04T08:16:20Z

Reduce macro complexity by using the new ___wait_event() helper. No change in behaviour, identical generated code. Reviewed-by: Oleg Nesterov Signed-off-by: Peter Zijlstra Link: http://lkml.kernel.org/r/20131002092528.831085521@infradead.org Signed-off-by: Ingo Molnar