linux-toradex.git/arch/um/drivers/hostaudio_kern.c, branch v4.4.95

module: add per-module param_lock

2015-06-23T05:57:38+00:00

Add a "param_lock" mutex to each module, and update params.c to use
the correct built-in or module mutex while locking kernel params.
Remove the kparam_block_sysfs_r/w() macros, replace them with direct
calls to kernel_param_[un]lock(module).

The kernel param code currently uses a single mutex to protect
modification of any and all kernel params.  While this generally works,
there is one specific problem with it; a module callback function
cannot safely load another module, i.e. with request_module() or even
with indirect calls such as crypto_has_alg().  If the module to be
loaded has any of its params configured (e.g. with a /etc/modprobe.d/*
config file), then the attempt will result in a deadlock between the
first module param callback waiting for modprobe, and modprobe trying to
lock the single kernel param mutex to set the new module's param.

This fixes that by using per-module mutexes, so that each individual module
is protected against concurrent changes in its own kernel params, but is
not blocked by changes to other module params.  All built-in modules
continue to use the built-in mutex, since they will always be loaded at
runtime and references (e.g. request_module(), crypto_has_alg()) to them
will never cause load-time param changing.

This also simplifies the interface used by modules to block sysfs access
to their params; while there are currently functions to block and unblock
sysfs param access which are split up by read and write and expect a single
kernel param to be passed, their actual operation is identical and applies
to all params, not just the one passed to them; they simply lock and unlock
the global param mutex.  They are replaced with direct calls to
kernel_param_[un]lock(THIS_MODULE), which locks THIS_MODULE's param_lock, or
if the module is built-in, it locks the built-in mutex.

Suggested-by: Rusty Russell 
Signed-off-by: Dan Streetman 
Signed-off-by: Rusty Russell

um: get rid of pointless include "..." where include <...> will do

2012-10-09T20:28:45+00:00

Signed-off-by: Al Viro 
Signed-off-by: Richard Weinberger

Merge branch 'config' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/bkl

2010-10-22T17:43:11+00:00

* 'config' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/bkl:
  BKL: introduce CONFIG_BKL.
  dabusb: remove the BKL
  sunrpc: remove the big kernel lock
  init/main.c: remove BKL notations
  blktrace: remove the big kernel lock
  rtmutex-tester: make it build without BKL
  dvb-core: kill the big kernel lock
  dvb/bt8xx: kill the big kernel lock
  tlclk: remove big kernel lock
  fix rawctl compat ioctls breakage on amd64 and itanic
  uml: kill big kernel lock
  parisc: remove big kernel lock
  cris: autoconvert trivial BKL users
  alpha: kill big kernel lock
  isapnp: BKL removal
  s390/block: kill the big kernel lock
  hpet: kill BKL, add compat_ioctl

uml: kill big kernel lock

2010-10-19T09:29:42+00:00

Three uml device drivers still use the big kernel lock,
but all of them can be safely converted to using
a per-driver mutex instead. Most likely this is not
even necessary, so after further review these can
and should be removed as well.

The exec system call no longer requires the BKL either,
so remove it from there, too.

Signed-off-by: Arnd Bergmann 
Cc: Jeff Dike 
Cc: user-mode-linux-devel@lists.sourceforge.net

uml: fix build

2010-10-15T21:42:24+00:00

Fix a build error introduced by d6d1b650ae6acce73d55dd024 ("param: simple
locking for sysfs-writable charp parameters").

    CC      arch/um/kernel/trap.o
  arch/um/drivers/hostaudio_kern.c: In function 'hostaudio_open':
  arch/um/drivers/hostaudio_kern.c:204: error: '__param_dsp' undeclared (first use in this function)
  arch/um/drivers/hostaudio_kern.c:204: error: (Each undeclared identifier is reported only once
  arch/um/drivers/hostaudio_kern.c:204: error: for each function it appears in.)
  arch/um/drivers/hostaudio_kern.c: In function 'hostmixer_open_mixdev':
  arch/um/drivers/hostaudio_kern.c:265: error: '__param_mixer' undeclared (first use in this function)
  arch/um/drivers/hostaudio_kern.c:272: error: '__param_dsp' undeclared (first use in this function)

Reported-by: Toralf Förster 
Tested-by: Toralf Förster 
Cc: Rusty Russell 
Cc: Takashi Iwai 
Cc: Jeff Dike 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

param: simple locking for sysfs-writable charp parameters

2010-08-11T13:34:31+00:00

Since the writing to sysfs can free the old one, we need to block that
when we access the charp variables.

Signed-off-by: Rusty Russell 
Reviewed-by: Takashi Iwai 
Tested-by: Phil Carmody 
Cc: Jeff Dike 
Cc: Dan Williams 
Cc: John W. Linville 
Cc: Jing Huang 
Cc: James E.J. Bottomley 
Cc: Greg Kroah-Hartman 
Cc: Johannes Berg 
Cc: David S. Miller 
Cc: user-mode-linux-devel@lists.sourceforge.net
Cc: libertas-dev@lists.infradead.org
Cc: linux-wireless@vger.kernel.org
Cc: netdev@vger.kernel.org
Cc: linux-scsi@vger.kernel.org
Cc: linux-usb@vger.kernel.org

sound: push BKL into open functions

2010-07-12T15:41:05+00:00

This moves the lock_kernel() call from soundcore_open
to the individual OSS device drivers, where we can deal
with it one driver at a time if needed, or just kill
off the drivers.

All core components in ALSA already provide
adequate locking in their open()-functions
and do not require the big kernel lock, so
there is no need to add the BKL there.

Signed-off-by: Arnd Bergmann 
Signed-off-by: Takashi Iwai

uml: Convert to unlocked_ioctls to remove implicit BKL

2010-05-17T03:27:42+00:00

Convert hostaudio_ioctl and hostmixer_ioctl_mixdev to
unlocked_ioctl without pushdown.

There is nothing to protect inside, the synchronization
is made from the host already.

Signed-off-by: John Kacur 
Cc: Arnd Bergmann 
Cc: Thomas Gleixner 
Cc: Ingo Molnar 
Cc: Jeff Dike 
Signed-off-by: Frederic Weisbecker

uml: fix errno return

2008-05-13T15:02:21+00:00

Error returns are negative.

Signed-off-by: Johann Felix Soden 
Signed-off-by: Jeff Dike 
Cc: WANG Cong 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

uml: arch/um/drivers formatting

2007-10-16T16:43:09+00:00

Style fixes for the rest of the drivers.  arch/um/drivers should be pretty
CodingStyle-compliant now.

Except for the ubd driver, which will have to be treated separately.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Jeff Dike 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds