linux-toradex.git/ipc, branch v2.6.27.8

sysvipc: fix the ipc structures initialization

2008-12-05T18:55:11+00:00

commit e00b4ff7ebf098b11b11be403921c1cf41d9e321 upstream.

A problem was found while reviewing the code after Bugzilla bug
http://bugzilla.kernel.org/show_bug.cgi?id=11796.

In ipc_addid(), the newly allocated ipc structure is inserted into the
ipcs tree (i.e made visible to readers) without locking it.  This is not
correct since its initialization continues after it has been inserted in
the tree.

This patch moves the ipc structure lock initialization + locking before
the actual insertion.

Signed-off-by: Nadia Derbey 
Reported-by: Clement Calmels 
Cc: Manfred Spraul 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

[PATCH] kill nameidata passing to permission(), rename to inode_permission()

2008-07-27T00:53:31+00:00

Incidentally, the name that gives hundreds of false positives on grep
is not a good idea...

Signed-off-by: Al Viro

SL*B: drop kmem cache argument from constructor

2008-07-26T19:00:07+00:00

Kmem cache passed to constructor is only needed for constructors that are
themselves multiplexeres.  Nobody uses this "feature", nor does anybody uses
passed kmem cache in non-trivial way, so pass only pointer to object.

Non-trivial places are:
	arch/powerpc/mm/init_64.c
	arch/powerpc/mm/hugetlbpage.c

This is flag day, yes.

Signed-off-by: Alexey Dobriyan 
Acked-by: Pekka Enberg 
Acked-by: Christoph Lameter 
Cc: Jon Tollefson 
Cc: Nick Piggin 
Cc: Matt Mackall 
[akpm@linux-foundation.org: fix arch/powerpc/mm/hugetlbpage.c]
[akpm@linux-foundation.org: fix mm/slab.c]
[akpm@linux-foundation.org: fix ubifs]
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

ipc: do not use a negative value to re-enable msgmni automatic recomputing

2008-07-25T17:53:42+00:00

This patch proposes an alternative to the "magical
positive-versus-negative number trick" Andrew complained about last week
in http://lkml.org/lkml/2008/6/24/418.

This had been introduced with the patches that scale msgmni to the amount
of lowmem.  With these patches, msgmni has a registered notification
routine that recomputes msgmni value upon memory add/remove or ipc
namespace creation/ removal.

When msgmni is changed from user space (i.e.  value written to the proc
file), that notification routine is unregistered, and the way to make it
registered back is to write a negative value into the proc file.  This is
the "magical positive-versus-negative number trick".

To fix this, a new proc file is introduced: /proc/sys/kernel/auto_msgmni.
This file acts as ON/OFF for msgmni automatic recomputing.

With this patch, the process is the following:
1) kernel boots in "automatic recomputing mode"
   /proc/sys/kernel/msgmni contains the value that has been computed (depends
                           on lowmem)
   /proc/sys/kernel/automatic_msgmni contains "1"

2) echo  > /proc/sys/kernel/msgmni
   . sets msg_ctlmni to 
   . de-activates automatic recomputing (i.e. if, say, some memory is added
     msgmni won't be recomputed anymore)
   . /proc/sys/kernel/automatic_msgmni now contains "0"

3) echo "0" > /proc/sys/kernel/automatic_msgmni
   . de-activates msgmni automatic recomputing
     this has the same effect as 2) except that msg_ctlmni's value stays
     blocked at its current value)

3) echo "1" > /proc/sys/kernel/automatic_msgmni
   . recomputes msgmni's value based on the current available memory size
     and number of ipc namespaces
   . re-activates automatic recomputing for msgmni.

Signed-off-by: Nadia Derbey 
Cc: Solofo Ramangalahy 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

ipc: use simple_read_from_buffer()

2008-07-25T17:53:42+00:00

Also this patch kills unneccesary trailing NULL character.

Signed-off-by: Akinobu Mita 
Cc: Nadia Derbey 
Cc: Manfred Spraul 
Cc: Pierre Peiffer 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

ipc/sem.c: rewrite undo list locking

2008-07-25T17:53:42+00:00

The attached patch:
- reverses the locking order of ulp->lock and sem_lock:
  Previously, it was first ulp->lock, then inside sem_lock.
  Now it's the other way around.
- converts the undo structure to rcu.

Benefits:
- With the old locking order, IPC_RMID could not kfree the undo structures.
  The stale entries remained in the linked lists and were released later.
- The patch fixes a a race in semtimedop(): if both IPC_RMID and a semget() that
  recreates exactly the same id happen between find_alloc_undo() and sem_lock,
  then semtimedop() would access already kfree'd memory.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Manfred Spraul 
Reviewed-by: Nadia Derbey 
Cc: Pierre Peiffer 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

ipc/sem.c: convert sem_array.sem_pending to struct list_head

2008-07-25T17:53:42+00:00

sem_array.sem_pending is a double linked list, the attached patch converts
it to struct list_head.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Manfred Spraul 
Reviewed-by: Nadia Derbey 
Cc: Pierre Peiffer 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

ipc/sem.c: remove unused entries from struct sem_queue

2008-07-25T17:53:42+00:00

sem_queue.sma and sem_queue.id were never used, the attached patch removes
them.

Signed-off-by: Manfred Spraul 
Reviewed-by: Nadia Derbey 
Cc: Pierre Peiffer 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

ipc/sem.c: convert undo structures to struct list_head

2008-07-25T17:53:42+00:00

The undo structures contain two linked lists, the attached patch replaces
them with generic struct list_head lists.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Manfred Spraul 
Cc: Nadia Derbey 
Cc: Pierre Peiffer 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

ipc: get rid of ipc_lock_down()

2008-07-25T17:53:42+00:00

Remove the ipc_lock_down() routines: they used to call idr_find() locklessly
(given that the ipc ids lock was already held), so they are not needed
anymore.

Signed-off-by: Nadia Derbey 
Acked-by: "Paul E. McKenney" 
Cc: Manfred Spraul 
Cc: Jim Houston 
Cc: Pierre Peiffer 
Acked-by: Rik van Riel 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds