linux.git/drivers/char/ttyprintk.c, branch v5.9

ttyprintk: remove redundant initialization of variable ret

2020-07-10T12:50:51+00:00

The variable ret is being initialized with a value that is never read
and it is being updated later with a new value.  The initialization is
redundant and can be removed.

Addresses-Coverity: ("Unused value")
Signed-off-by: Colin Ian King 
Link: https://lore.kernel.org/r/20200611153108.927614-1-colin.king@canonical.com
Signed-off-by: Greg Kroah-Hartman

ttyprintk: fix a potential deadlock in interrupt context issue

2020-01-14T13:37:54+00:00

tpk_write()/tpk_close() could be interrupted when holding a mutex, then
in timer handler tpk_write() may be called again trying to acquire same
mutex, lead to deadlock.

Google syzbot reported this issue with CONFIG_DEBUG_ATOMIC_SLEEP
enabled:

BUG: sleeping function called from invalid context at
kernel/locking/mutex.c:938
in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 0, name: swapper/1
1 lock held by swapper/1/0:
...
Call Trace:
  
  dump_stack+0x197/0x210
  ___might_sleep.cold+0x1fb/0x23e
  __might_sleep+0x95/0x190
  __mutex_lock+0xc5/0x13c0
  mutex_lock_nested+0x16/0x20
  tpk_write+0x5d/0x340
  resync_tnc+0x1b6/0x320
  call_timer_fn+0x1ac/0x780
  run_timer_softirq+0x6c3/0x1790
  __do_softirq+0x262/0x98c
  irq_exit+0x19b/0x1e0
  smp_apic_timer_interrupt+0x1a3/0x610
  apic_timer_interrupt+0xf/0x20
  

See link https://syzkaller.appspot.com/bug?extid=2eeef62ee31f9460ad65 for
more details.

Fix it by using spinlock in process context instead of mutex and having
interrupt disabled in critical section.

Reported-by: syzbot+2eeef62ee31f9460ad65@syzkaller.appspotmail.com
Signed-off-by: Zhenzhong Duan 
Cc: Arnd Bergmann 
Cc: Greg Kroah-Hartman 
Link: https://lore.kernel.org/r/20200113034842.435-1-zhenzhong.duan@gmail.com
Signed-off-by: Greg Kroah-Hartman

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 402

2019-06-05T15:37:13+00:00

Based on 1 normalized pattern(s):

  this program is free software you can redistribute it and or modify
  it under the smems of the gnu general public license as published by
  the free software foundation version 2 of the license

extracted by the scancode license scanner the SPDX license identifier

  GPL-2.0-only

has been chosen to replace the boilerplate/reference in 5 file(s).

Signed-off-by: Thomas Gleixner 
Reviewed-by: Armijn Hemel 
Reviewed-by: Allison Randal 
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190531190111.946565886@linutronix.de
Signed-off-by: Greg Kroah-Hartman

ttyprintk: make the printk log level configurable

2018-11-09T16:58:18+00:00

For some use cases it is handy to use a different printk log level than the
default (info) for the messages written to ttyprintk, so add a Kconfig
option similar to what we have for default console loglevel.

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

ttyprintk: Neaten and simplify printing

2016-09-13T15:30:17+00:00

The code is a bit obscure.

Simplify it by using a single routine to flush the tpk_buffer and
emit the buffer prefixed with "[U] ".

Signed-off-by: Joe Perches 
Signed-off-by: Greg Kroah-Hartman

char: constify tty_port_operations structs

2016-02-07T07:31:08+00:00

Constifies tty_port_operations structure in
the char driver since it is not modified
after its initialization.

Detected and found using Coccinelle.

Suggested-by: Julia Lawall 
Signed-off-by: Aya Mahfouz 
Acked-by: Arnd Bergmann 
Signed-off-by: Greg Kroah-Hartman

ttyprintk: Allow built as a module

2014-04-16T21:21:06+00:00

The driver is well written to be used as a module, just the exit call
is missing.

Reviewed-by: Jean Delvare 
Signed-off-by: Takashi Iwai 
Signed-off-by: Greg Kroah-Hartman

ttyprintk: Fix wrong tty_unregister_driver() call in the error path

2014-04-16T21:21:06+00:00

ttyprintk driver calls tty_unregister_driver() wrongly in the error
path of tty_register_driver().  Also, setting ttyprintk_driver to NULL
is utterly superfluous, so let's get rid of it, too.

Reported-by: Jean Delvare 
Reviewed-by: Jean Delvare 
Signed-off-by: Takashi Iwai 
Signed-off-by: Greg Kroah-Hartman

drivers/char: don't use module_init in non-modular ttyprintk.c

2014-01-13T22:57:20+00:00

The TTY_PRINTK option is bool, and hence this code is either
present or absent.  It will never be modular, so using
module_init as an alias for __initcall is rather misleading.

Fix this up now, so that we can relocate module_init from
init.h into module.h in the future.  If we don't do this, we'd
have to add module.h to obviously non-modular code, and that
would be a worse thing.

Note that direct use of __initcall is discouraged, vs. one
of the priority categorized subgroups.  As __initcall gets
mapped onto device_initcall, our use of device_initcall
directly in this change means that the runtime impact is
zero -- it will remain at level 6 in initcall ordering.

Signed-off-by: Paul Gortmaker 
Signed-off-by: Greg Kroah-Hartman

ttyprintk: Fix NULL pointer deref by setting tty_port ops after initializing port

2013-05-21T17:13:23+00:00

tty_port_init() zeroes out the tty port, which means that we have to set the
ops pointer /after/, not before this call.  Otherwise, tty_port_open will crash
when it tries to deref ops, which is now a NULL pointer.

Signed-off-by: Darrick J. Wong 
Signed-off-by: Greg Kroah-Hartman