Subject: [merged] ipc-document-general-ipc-locking-scheme.patch removed from -mm tree
To: davidlohr.bueso@xxxxxx,manfred@xxxxxxxxxxxxxxxx,riel@xxxxxxxxxx,sedat.dilek@xxxxxxxxx,mm-commits@xxxxxxxxxxxxxxx
From: akpm@xxxxxxxxxxxxxxxxxxxx
Date: Thu, 12 Sep 2013 12:50:59 -0700
The patch titled
Subject: ipc: document general ipc locking scheme
has been removed from the -mm tree. Its filename was
ipc-document-general-ipc-locking-scheme.patch
This patch was dropped because it was merged into mainline or a subsystem tree
------------------------------------------------------
From: Davidlohr Bueso <davidlohr.bueso@xxxxxx>
Subject: ipc: document general ipc locking scheme
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>
---
ipc/util.c | 8 ++++++++
1 file changed, 8 insertions(+)
diff -puN ipc/util.c~ipc-document-general-ipc-locking-scheme ipc/util.c
--- a/ipc/util.c~ipc-document-general-ipc-locking-scheme
+++ a/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 -mm which might be from davidlohr.bueso@xxxxxx are
origin.patch
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