linux-stable.git/drivers/char/misc.c, branch v4.2.4

char: misc: restore MISC_DYNAMIC_MINOR on device_create() failure

2015-05-31T21:38:21+00:00

On attempt to register a dynamic minor misc device its minor number is
updated to a virtual minor number prior to device_create() call,
however on error path misc->minor == MISC_DYNAMIC_MINOR is not
restored.

Following the rule of thumb that a function returning an error must
not change the state of the caller, assign MISC_DYNAMIC_MINOR back.

The problem is met in a sutuation, when subsys_initcall(misc_init) is
not yet called and misc_class is not created, but misc_register()
modifies statically defined ".minor = MISC_DYNAMIC_MINOR", therefore
implicitly changing the client's logic on next attempt (e.g. retrying
from deferred list) to register a misc device, whose minor number is
converted from dynamic to some unknown static one.

Signed-off-by: Vladimir Zapolskiy 
Signed-off-by: Greg Kroah-Hartman

drivers: char: misc.c: remove trailing whitespace

2015-05-24T19:11:55+00:00

Remove trailing whitespace from several lines in drivers/char/misc.c
This was done using scripts/cleanfile

Signed-off-by: Tal Shorer 
Signed-off-by: Greg Kroah-Hartman

misc: pass miscdevice through file's private_data

2015-04-03T14:15:30+00:00

Make the miscdevice accessible through the file's private_data.

Previously, this was done only when an open() file operation had been
registered. If no custom open() file operation was defined,
private_data was set to NULL.

This subtle quirk was confusing, to the point where kernel code
registered *empty* file open operations to have private_data point to
the misc device structure and avoid duplicating that logic.

And it could easily lead to bugs, where the addition or removal of a
custom open() file operation surprisingly changes the initial value of
a file's private_data structure.

To resolve this, we now place the miscdevice in the file's private_data
member unconditionally when open() is called.

Signed-off-by: Tom Van Braeckel 
Signed-off-by: Greg Kroah-Hartman

misc: Add attribute groups

2015-03-25T10:44:52+00:00

Add groups field to struct miscdevice for passing the attribute groups
at device creation.  In this way, the driver can avoid the manual call
of device_create_file() after the device registration, which is
basically a racy operation, in addition to the reduction of manual
device_remove_file() calls.

Signed-off-by: Takashi Iwai 
Signed-off-by: Greg Kroah-Hartman

char: misc: document behaviour of open()

2015-03-25T10:36:38+00:00

an open syscall now assignes file->private_data to a pointer to the
miscdevice structure. This reminds people not to duplicate code if
they want this and not to depend on it being NULL.

Signed-off-by: Martin Kepplinger 
Signed-off-by: Greg Kroah-Hartman

Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

2013-11-13T06:34:18+00:00

Pull vfs updates from Al Viro:
 "All kinds of stuff this time around; some more notable parts:

   - RCU'd vfsmounts handling
   - new primitives for coredump handling
   - files_lock is gone
   - Bruce's delegations handling series
   - exportfs fixes

  plus misc stuff all over the place"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (101 commits)
  ecryptfs: ->f_op is never NULL
  locks: break delegations on any attribute modification
  locks: break delegations on link
  locks: break delegations on rename
  locks: helper functions for delegation breaking
  locks: break delegations on unlink
  namei: minor vfs_unlink cleanup
  locks: implement delegations
  locks: introduce new FL_DELEG lock flag
  vfs: take i_mutex on renamed file
  vfs: rename I_MUTEX_QUOTA now that it's not used for quotas
  vfs: don't use PARENT/CHILD lock classes for non-directories
  vfs: pull ext4's double-i_mutex-locking into common code
  exportfs: fix quadratic behavior in filehandle lookup
  exportfs: better variable name
  exportfs: move most of reconnect_path to helper function
  exportfs: eliminate unused "noprogress" counter
  exportfs: stop retrying once we race with rename/remove
  exportfs: clear DISCONNECTED on all parents sooner
  exportfs: more detailed comment for path_reconnect
  ...

consolidate the reassignments of ->f_op in ->open() instances

2013-10-25T03:34:53+00:00

Signed-off-by: Al Viro

Drivers: char: misc: 'misc_deregister()' changed the 'mutex_unlock' logic upon an error

2013-09-26T15:53:23+00:00

This change improves code readability & is less error-prone.
For example: case adding more error paths one should remember to call 'mutex_unlock'

Signed-off-by: Elad Wexler 
Signed-off-by: Greg Kroah-Hartman

drivers/char/misc.c:misc_register(): do not loop on misc_list unconditionally

2013-02-28T03:10:21+00:00

If the minor number is assigned dynamically, there is no need to search
for misc->minor in misc_list, since misc->minor == MISC_DYNAMIC_MINOR.

[akpm@linux-foundation.org: reduce scope of local `c']
Signed-off-by: Dae S. Kim 
Cc: Arnd Bergmann 
Cc: Greg KH 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

switch device_get_devnode() and ->devnode() to umode_t *

2012-01-04T03:54:55+00:00

both callers of device_get_devnode() are only interested in lower 16bits
and nobody tries to return anything wider than 16bit anyway.

Signed-off-by: Al Viro