linux.git/drivers/staging/android/ashmem.c, branch v3.10

staging: android: ashmem: Add support for 32bit ashmem calls in a 64bit kernel

2013-03-06T00:49:43+00:00

Android's shared memory subsystem, Ashmem, does not support calls from a
32bit userspace in a 64 bit kernel. This patch adds support for syscalls
coming from a 32bit userspace in a 64bit kernel.

The patch has been successfully tested on ARMv8 AEM(64bit
platform model) and Versatile Express A9(32bit platform).

v2: Fix missing compat.h include.

Signed-off-by: Serban Constantinescu 
Acked-by: Arve Hjønnevåg 
Acked-by: John Stultz 
Signed-off-by: Greg Kroah-Hartman

staging: android: ashmem: get_name,set_name not to hold ashmem_mutex

2013-03-05T08:35:22+00:00

Problem:
There exists a path in ashmem driver that could lead to acquistion
of mm->mmap_sem, ashmem_mutex in reverse order. This could lead
to deadlock in the system.
For Example, assume that mmap is called on a ashmem region
in the context of a thread say T1.
 sys_mmap_pgoff (1. acquires mm->mmap_sem)
  |
   --> mmap_region
 	|
         ----> ashmem_mmap (2. acquires asmem_mutex)
 Now if there is a context switch after 1 and before 2,
 and if another thread T2 (that shares the mm struct) invokes an
 ioctl say ASHMEM_GET_NAME, this can lead to the following path

ashmem_ioctl
  |
  -->get_name (3. acquires ashmem_mutex)
	|
	---> copy_to_user (4. acquires the mm->mmap_sem)
Note that the copy_to_user could lead to a valid fault if no
physical page is allocated yet for the user address passed.
Now T1 has mmap_sem and is waiting for ashmem_mutex.
and T2 has the ashmem_mutex and is waiting for mmap_sem
Thus leading to deadlock.

Solution:
Do not call copy_to_user or copy_from_user while holding the
ahsmem_mutex. Instead copy this to a local buffer that lives
in the stack while holding this lock. This will maintain data
integrity as well never reverse the lock order.

Testing:
Created a unit test case to reproduce the problem.
Used the same to test this fix on kernel version 3.4.0
Ported the same patch to 3.8

Signed-off-by: Shankar Brahadeeswaran 
Reviewed-by: Dan Carpenter 
Acked-by: Dan Carpenter 
Signed-off-by: Greg Kroah-Hartman

mm: kill vma flag VM_CAN_NONLINEAR

2012-10-09T07:22:17+00:00

Move actual pte filling for non-linear file mappings into the new special
vma operation: ->remap_pages().

Filesystems must implement this method to get non-linear mapping support,
if it uses filemap_fault() then generic_file_remap_pages() can be used.

Now device drivers can implement this method and obtain nonlinear vma support.

Signed-off-by: Konstantin Khlebnikov 
Cc: Alexander Viro 
Cc: Carsten Otte 
Cc: Chris Metcalf 	#arch/tile
Cc: Cyrill Gorcunov 
Cc: Eric Paris 
Cc: H. Peter Anvin 
Cc: Hugh Dickins 
Cc: Ingo Molnar 
Cc: James Morris 
Cc: Jason Baron 
Cc: Kentaro Takeda 
Cc: Matt Helsley 
Cc: Nick Piggin 
Cc: Oleg Nesterov 
Cc: Peter Zijlstra 
Cc: Robert Richter 
Cc: Suresh Siddha 
Cc: Tetsuo Handa 
Cc: Venkatesh Pallipadi 
Acked-by: Linus Torvalds 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

staging: android: ashmem: Fix comment/license formatting

2012-08-14T02:04:25+00:00

Signed-off-by: Cruz Julian Bishop 
Signed-off-by: Greg Kroah-Hartman

staging: Android: Fix some checkpatch warnings

2012-06-12T18:20:17+00:00

Warnings reported by checkpatch.pl have been fixed.

Cc: Brian Swetland 
Signed-off-by: Sachin Kamat 
Signed-off-by: Greg Kroah-Hartman

mm/fs: route MADV_REMOVE to FALLOC_FL_PUNCH_HOLE

2012-05-29T23:22:22+00:00

Now tmpfs supports hole-punching via fallocate(), switch madvise_remove()
to use do_fallocate() instead of vmtruncate_range(): which extends
madvise(,,MADV_REMOVE) support from tmpfs to ext4, ocfs2 and xfs.

There is one more user of vmtruncate_range() in our tree,
staging/android's ashmem_shrink(): convert it to use do_fallocate() too
(but if its unpinned areas are already unmapped - I don't know - then it
would do better to use shmem_truncate_range() directly).

Based-on-patch-by: Cong Wang 
Signed-off-by: Hugh Dickins 
Cc: Christoph Hellwig 
Cc: Al Viro 
Cc: Colin Cross 
Cc: John Stultz 
Cc: Greg Kroah-Hartman 
Cc: "Theodore Ts'o" 
Cc: Andreas Dilger 
Cc: Mark Fasheh 
Cc: Joel Becker 
Cc: Dave Chinner 
Cc: Ben Myers 
Cc: Michael Kerrisk 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[media] mm/drivers: use vm_flags_t for vma flags

2012-04-10T18:44:21+00:00

Signed-off-by: Konstantin Khlebnikov 
Cc: linux-media@vger.kernel.org
Cc: devel@driverdev.osuosl.org
Cc: Laurent Pinchart 
Cc: Mauro Carvalho Chehab 
Cc: Greg Kroah-Hartman 
Cc: John Stultz 
Cc: "Arve Hjønnevåg" 
Acked-by: Laurent Pinchart 
Acked-by: Greg Kroah-Hartman 
Signed-off-by: Mauro Carvalho Chehab

drivers/staging/android/ashmem.c: Cleanups

2012-02-09T00:47:51+00:00

Minor cleanups that consist of removal of a whitespace and
make file_operations const.

Signed-off-by: Tracey Dent 
Signed-off-by: Greg Kroah-Hartman

ashmem: Whitespace cleanups

2011-12-21T21:40:25+00:00

Fixes checkpatch warnings with the ashmem.c file

CC: Brian Swetland 
CC: Colin Cross 
CC: Arve Hjønnevåg 
CC: Dima Zavin 
CC: Robert Love 
Signed-off-by: John Stultz 
Signed-off-by: Greg Kroah-Hartman

ashmem: Fix arguments to ashmem_shrink

2011-12-21T21:40:24+00:00

The arguments to shrink functions have changed, update
ashmem_shrink to match.

Signed-off-by: Colin Cross 
[jstultz: tweaked commit subject]
CC: Brian Swetland 
CC: Colin Cross 
CC: Arve Hjønnevåg 
CC: Dima Zavin 
CC: Robert Love 
Signed-off-by: John Stultz 
Signed-off-by: Greg Kroah-Hartman