linux-toradex.git/kernel/printk, branch toradex_vf_4.1

printk: use rcuidle console tracepoint

2017-03-06T22:31:14+00:00

[ Upstream commit fc98c3c8c9dcafd67adcce69e6ce3191d5306c9c ]

Use rcuidle console tracepoint because, apparently, it may be issued
from an idle CPU:

  hw-breakpoint: Failed to enable monitor mode on CPU 0.
  hw-breakpoint: CPU 0 failed to disable vector catch

  ===============================
  [ ERR: suspicious RCU usage.  ]
  4.10.0-rc8-next-20170215+ #119 Not tainted
  -------------------------------
  ./include/trace/events/printk.h:32 suspicious rcu_dereference_check() usage!

  other info that might help us debug this:

  RCU used illegally from idle CPU!
  rcu_scheduler_active = 2, debug_locks = 0
  RCU used illegally from extended quiescent state!
  2 locks held by swapper/0/0:
   #0:  (cpu_pm_notifier_lock){......}, at: [] cpu_pm_exit+0x10/0x54
   #1:  (console_lock){+.+.+.}, at: [] vprintk_emit+0x264/0x474

  stack backtrace:
  CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.10.0-rc8-next-20170215+ #119
  Hardware name: Generic OMAP4 (Flattened Device Tree)
    console_unlock
    vprintk_emit
    vprintk_default
    printk
    reset_ctrl_regs
    dbg_cpu_pm_notify
    notifier_call_chain
    cpu_pm_exit
    omap_enter_idle_coupled
    cpuidle_enter_state
    cpuidle_enter_state_coupled
    do_idle
    cpu_startup_entry
    start_kernel

This RCU warning, however, is suppressed by lockdep_off() in printk().
lockdep_off() increments the ->lockdep_recursion counter and thus
disables RCU_LOCKDEP_WARN() and debug_lockdep_rcu_enabled(), which want
lockdep to be enabled "current->lockdep_recursion == 0".

Link: http://lkml.kernel.org/r/20170217015932.11898-1-sergey.senozhatsky@gmail.com
Signed-off-by: Sergey Senozhatsky 
Reported-by: Tony Lindgren 
Tested-by: Tony Lindgren 
Acked-by: Paul E. McKenney 
Acked-by: Steven Rostedt (VMware) 
Cc: Petr Mladek 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: Tony Lindgren 
Cc: Russell King 
Cc:  [3.4+]
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Sasha Levin

printk: do cond_resched() between lines while outputting to consoles

2016-02-03T21:23:18+00:00

[ Upstream commit 8d91f8b15361dfb438ab6eb3b319e2ded43458ff ]

@console_may_schedule tracks whether console_sem was acquired through
lock or trylock.  If the former, we're inside a sleepable context and
console_conditional_schedule() performs cond_resched().  This allows
console drivers which use console_lock for synchronization to yield
while performing time-consuming operations such as scrolling.

However, the actual console outputting is performed while holding
irq-safe logbuf_lock, so console_unlock() clears @console_may_schedule
before starting outputting lines.  Also, only a few drivers call
console_conditional_schedule() to begin with.  This means that when a
lot of lines need to be output by console_unlock(), for example on a
console registration, the task doing console_unlock() may not yield for
a long time on a non-preemptible kernel.

If this happens with a slow console devices, for example a serial
console, the outputting task may occupy the cpu for a very long time.
Long enough to trigger softlockup and/or RCU stall warnings, which in
turn pile more messages, sometimes enough to trigger the next cycle of
warnings incapacitating the system.

Fix it by making console_unlock() insert cond_resched() between lines if
@console_may_schedule.

Signed-off-by: Tejun Heo 
Reported-by: Calvin Owens 
Acked-by: Jan Kara 
Cc: Dave Jones 
Cc: Kyle McMartin 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Sasha Levin

security_syslog() should be called once only

2015-08-03T16:29:15+00:00

commit d194e5d666225b04c7754471df0948f645b6ab3a upstream.

The final version of commit 637241a900cb ("kmsg: honor dmesg_restrict
sysctl on /dev/kmsg") lost few hooks, as result security_syslog() are
processed incorrectly:

- open of /dev/kmsg checks syslog access permissions by using
  check_syslog_permissions() where security_syslog() is not called if
  dmesg_restrict is set.

- syslog syscall and /proc/kmsg calls do_syslog() where security_syslog
  can be executed twice (inside check_syslog_permissions() and then
  directly in do_syslog())

With this patch security_syslog() is called once only in all
syslog-related operations regardless of dmesg_restrict value.

Fixes: 637241a900cb ("kmsg: honor dmesg_restrict sysctl on /dev/kmsg")
Signed-off-by: Vasily Averin 
Cc: Kees Cook 
Cc: Josh Boyer 
Cc: Eric Paris 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

Merge tag 'tty-4.1-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty

2015-04-21T16:33:10+00:00

Pull tty/serial updates from Greg KH:
 "Here's the big tty/serial driver update for 4.1-rc1.

  It was delayed for a bit due to some questions surrounding some of the
  console command line parsing changes that are in here.  There's still
  one tiny regression for people who were previously putting multiple
  console command lines and expecting them all to be ignored for some
  odd reason, but Peter is working on fixing that.  If not, I'll send a
  revert for the offending patch, but I have faith that Peter can
  address it.

  Other than the console work here, there's the usual serial driver
  updates and changes, and a buch of 8250 reworks to try to make that
  driver easier to maintain over time, and have it support more devices
  in the future.

  All of these have been in linux-next for a while"

* tag 'tty-4.1-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty: (119 commits)
  n_gsm: Drop unneeded cast on netdev_priv
  sc16is7xx: expose RTS inversion in RS-485 mode
  serial: 8250_pci: port failed after wakeup from S3
  earlycon: 8250: Document kernel command line options
  earlycon: 8250: Fix command line regression
  earlycon: Fix __earlycon_table stride
  tty: clean up the tty time logic a bit
  serial: 8250_dw: only get the clock rate in one place
  serial: 8250_dw: remove useless ACPI ID check
  dmaengine: hsu: move memory allocation to GFP_NOWAIT
  dmaengine: hsu: remove redundant pieces of code
  serial: 8250_pci: add Intel Tangier support
  dmaengine: hsu: add Intel Tangier PCI ID
  serial: 8250_pci: replace switch-case by formula for Intel MID
  serial: 8250_pci: replace switch-case by formula
  tty: cpm_uart: replace CONFIG_8xx by CONFIG_CPM1
  serial: jsm: some off by one bugs
  serial: xuartps: Fix check in console_setup().
  serial: xuartps: Get rid of register access macros.
  serial: xuartps: Fix iobase use.
  ...

Merge branch 'iocb' into for-next

2015-04-12T02:24:41+00:00

console: Add extensible console matching

2015-03-26T15:16:20+00:00

Add match() method to struct console which allows the console to
perform console command line matching instead of (or in addition to)
default console matching (ie., by fixed name and index).

The match() method returns 0 to indicate a successful match; normal
console matching occurs if no match() method is defined or the
match() method returns non-zero. The match() method is expected to set
the console index if required.

Re-implement earlycon-to-console-handoff with direct matching of
"console=uart|uart8250,..." to the 8250 ttyS console.

Acked-by: Rob Herring 
Signed-off-by: Peter Hurley 
Signed-off-by: Greg Kroah-Hartman

fs: move struct kiocb to fs.h

2015-03-26T00:28:11+00:00

struct kiocb now is a generic I/O container, so move it to fs.h.
Also do a #include diet for aio.h while we're at it.

Signed-off-by: Christoph Hellwig 
Signed-off-by: Al Viro

fs: remove ki_nbytes

2015-03-13T03:50:23+00:00

There is no need to pass the total request length in the kiocb, as
we already get passed in through the iov_iter argument.

Signed-off-by: Christoph Hellwig 
Signed-off-by: Al Viro

Merge 4.0-rc3 into tty-testing

2015-03-09T06:08:37+00:00

This resolves a merge issue in drivers/tty/serial/8250/8250_pci.c

Signed-off-by: Greg Kroah-Hartman

console: Preserve index after console setup()

2015-03-07T02:55:08+00:00

Before register_console() calls the setup() method of the matched
console, the registering console index is already equal to the index
from the console command line; ie. newcon->index == c->index.

This change is also required to support extensible console matching;
(the command line index may have no relation to the console index
assigned by the console-defined match() function).

Signed-off-by: Peter Hurley 
Signed-off-by: Greg Kroah-Hartman