This is a note to let you know that I've just added the patch titled
ipc: document general ipc locking scheme
to the 3.11-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
ipc-document-general-ipc-locking-scheme.patch
and it can be found in the queue-3.11 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 05603c44a7627793219b0bd9a7b236099dc9cd9d Mon Sep 17 00:00:00 2001
From: Davidlohr Bueso <davidlohr.bueso@xxxxxx>
Date: Wed, 11 Sep 2013 14:26:26 -0700
Subject: ipc: document general ipc locking scheme
From: Davidlohr Bueso <davidlohr.bueso@xxxxxx>
commit 05603c44a7627793219b0bd9a7b236099dc9cd9d upstream.
As suggested by Andrew, add a generic initial locking scheme used
throughout all sysv ipc mechanisms. Documenting the ids rwsem, how rcu
can be enough to do the initial checks and when to actually acquire the
kern_ipc_perm.lock spinlock.
I found that adding it to util.c was generic enough.
Signed-off-by: Davidlohr Bueso <davidlohr.bueso@xxxxxx>
Tested-by: Sedat Dilek <sedat.dilek@xxxxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxx>
Cc: Manfred Spraul <manfred@xxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Mike Galbraith <efault@xxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
ipc/util.c | 8 ++++++++
1 file changed, 8 insertions(+)
--- a/ipc/util.c
+++ b/ipc/util.c
@@ -15,6 +15,14 @@
* Jun 2006 - namespaces ssupport
* OpenVZ, SWsoft Inc.
* Pavel Emelianov <xemul@xxxxxxxxxx>
+ *
+ * General sysv ipc locking scheme:
+ * when doing ipc id lookups, take the ids->rwsem
+ * rcu_read_lock()
+ * obtain the ipc object (kern_ipc_perm)
+ * perform security, capabilities, auditing and permission checks, etc.
+ * acquire the ipc lock (kern_ipc_perm.lock) throught ipc_lock_object()
+ * perform data updates (ie: SET, RMID, LOCK/UNLOCK commands)
*/
#include <linux/mm.h>
Patches currently in stable-queue which might be from davidlohr.bueso@xxxxxx are
queue-3.11/ipc-drop-ipc_lock_by_ptr.patch
queue-3.11/ipc-msg-drop-msg_unlock.patch
queue-3.11/ipc-shm-shorten-critical-region-in-shmctl_down.patch
queue-3.11/ipc-rename-ids-rw_mutex.patch
queue-3.11/ipc-shm-introduce-lockless-functions-to-obtain-the-ipc-object.patch
queue-3.11/ipc-shm-shorten-critical-region-for-shmat.patch
queue-3.11/ipc-shm-shorten-critical-region-for-shmctl.patch
queue-3.11/ipc-shm-introduce-shmctl_nolock.patch
queue-3.11/ipc-drop-ipcctl_pre_down.patch
queue-3.11/ipc-document-general-ipc-locking-scheme.patch
queue-3.11/ipc-shm-drop-shm_lock_check.patch
queue-3.11/ipc-shm-guard-against-non-existant-vma-in-shmdt-2.patch
queue-3.11/ipc-shm-cleanup-do_shmat-pasta.patch
queue-3.11/ipc-drop-ipc_lock_check.patch
queue-3.11/ipc-shm-make-shmctl_nolock-lockless.patch
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