linux-toradex.git/fs/proc/task_nommu.c, branch v4.5

proc: revert /proc//maps [stack:TID] annotation

2016-02-03T16:28:43+00:00

Commit b76437579d13 ("procfs: mark thread stack correctly in
proc//maps") added [stack:TID] annotation to /proc//maps.

Finding the task of a stack VMA requires walking the entire thread list,
turning this into quadratic behavior: a thousand threads means a
thousand stacks, so the rendering of /proc//maps needs to look at a
million combinations.

The cost is not in proportion to the usefulness as described in the
patch.

Drop the [stack:TID] annotation to make /proc//maps (and
/proc//numa_maps) usable again for higher thread counts.

The [stack] annotation inside /proc//task//maps is retained, as
identifying the stack VMA there is an O(1) operation.

Siddesh said:
 "The end users needed a way to identify thread stacks programmatically and
  there wasn't a way to do that.  I'm afraid I no longer remember (or have
  access to the resources that would aid my memory since I changed
  employers) the details of their requirement.  However, I did do this on my
  own time because I thought it was an interesting project for me and nobody
  really gave any feedback then as to its utility, so as far as I am
  concerned you could roll back the main thread maps information since the
  information is available in the thread-specific files"

Signed-off-by: Johannes Weiner 
Cc: "Kirill A. Shutemov" 
Cc: Siddhesh Poyarekar 
Cc: Shaohua Li 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

vfs: add seq_file_path() helper

2015-06-23T22:01:07+00:00

Turn
	seq_path(..., &file->f_path, ...);
into
	seq_file_path(..., file, ...);

Signed-off-by: Miklos Szeredi 
Signed-off-by: Al Viro

proc/maps: make vm_is_stack() logic namespace-friendly

2014-10-10T02:25:50+00:00

- Rename vm_is_stack() to task_of_stack() and change it to return
  "struct task_struct *" rather than the global (and thus wrong in
  general) pid_t.

- Add the new pid_of_stack() helper which calls task_of_stack() and
  uses the right namespace to report the correct pid_t.

  Unfortunately we need to define this helper twice, in task_mmu.c
  and in task_nommu.c. perhaps it makes sense to add fs/proc/util.c
  and move at least pid_of_stack/task_of_stack there to avoid the
  code duplication.

- Change show_map_vma() and show_numa_map() to use the new helper.

Signed-off-by: Oleg Nesterov 
Cc: Alexander Viro 
Cc: Cyrill Gorcunov 
Cc: "Eric W. Biederman" 
Cc: Greg Ungerer 
Cc: "Kirill A. Shutemov" 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

proc/maps: replace proc_maps_private->pid with "struct inode *inode"

2014-10-10T02:25:50+00:00

m_start() can use get_proc_task() instead, and "struct inode *"
provides more potentially useful info, see the next changes.

Signed-off-by: Oleg Nesterov 
Cc: Alexander Viro 
Cc: Cyrill Gorcunov 
Cc: "Eric W. Biederman" 
Cc: Greg Ungerer 
Cc: "Kirill A. Shutemov" 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

fs/proc/task_nommu.c: don't use priv->task->mm

2014-10-10T02:25:49+00:00

I do not know if CONFIG_PREEMPT/SMP is possible without CONFIG_MMU
but the usage of task->mm in m_stop(). The task can exit/exec before
we take mmap_sem, in this case m_stop() can hit NULL or unlock the
wrong rw_semaphore.

Also, this code uses priv->task != NULL to decide whether we need
up_read/mmput. This is correct, but we will probably kill priv->task.
Change m_start/m_stop to rely on IS_ERR_OR_NULL() like task_mmu.c does.

Signed-off-by: Oleg Nesterov 
Cc: Kirill A. Shutemov 
Cc: Cyrill Gorcunov 
Cc: "Eric W. Biederman" 
Acked-by: Greg Ungerer 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

fs/proc/task_nommu.c: shift mm_access() from m_start() to proc_maps_open()

2014-10-10T02:25:49+00:00

Copy-and-paste the changes from "fs/proc/task_mmu.c: shift mm_access()
from m_start() to proc_maps_open()" into task_nommu.c.

Change maps_open() to initialize priv->mm using proc_mem_open(), m_start()
can rely on atomic_inc_not_zero(mm_users) like task_mmu.c does.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Oleg Nesterov 
Cc: Kirill A. Shutemov 
Cc: Cyrill Gorcunov 
Cc: "Eric W. Biederman" 
Acked-by: Greg Ungerer 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

fs/proc/task_nommu.c: change maps_open() to use __seq_open_private()

2014-10-10T02:25:49+00:00

Cleanup and preparation. maps_open() can use __seq_open_private()
like proc_maps_open() does.

[akpm@linux-foundation.org: deuglify]
Signed-off-by: Oleg Nesterov 
Cc: Kirill A. Shutemov 
Cc: Cyrill Gorcunov 
Cc: "Eric W. Biederman" 
Acked-by: Greg Ungerer 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

seq_file: remove "%n" usage from seq_file users

2013-11-15T00:32:20+00:00

All seq_printf() users are using "%n" for calculating padding size,
convert them to use seq_setwidth() / seq_pad() pair.

Signed-off-by: Tetsuo Handa 
Signed-off-by: Kees Cook 
Cc: Joe Perches 
Cc: David Miller 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

new helper: file_inode(file)

2013-02-23T04:31:31+00:00

Signed-off-by: Al Viro

proc: remove mm_for_maps()

2012-06-01T00:49:28+00:00

mm_for_maps() is a simple wrapper for mm_access(), and the name is
misleading, so just remove it and use mm_access() directly.

Signed-off-by: Cong Wang 
Cc: Oleg Nesterov 
Cc: Alexey Dobriyan 
Acked-by: Hugh Dickins 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds