Subject: [merged] ipc-update-locking-scheme-comments.patch removed from -mm tree To: davidlohr@xxxxxx,manfred@xxxxxxxxxxxxxxxx,mm-commits@xxxxxxxxxxxxxxx From: akpm@xxxxxxxxxxxxxxxxxxxx Date: Thu, 17 Oct 2013 11:12:55 -0700 The patch titled Subject: ipc: update locking scheme comments has been removed from the -mm tree. Its filename was ipc-update-locking-scheme-comments.patch This patch was dropped because it was merged into mainline or a subsystem tree ------------------------------------------------------ From: Davidlohr Bueso <davidlohr@xxxxxx> Subject: ipc: update locking scheme comments The initial documentation was a bit incomplete, update accordingly. [akpm@xxxxxxxxxxxxxxxxxxxx: make it more readable in 80 columns] Signed-off-by: Davidlohr Bueso <davidlohr@xxxxxx> Acked-by: Manfred Spraul <manfred@xxxxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- ipc/util.c | 27 +++++++++++++++++++++------ 1 file changed, 21 insertions(+), 6 deletions(-) diff -puN ipc/util.c~ipc-update-locking-scheme-comments ipc/util.c --- a/ipc/util.c~ipc-update-locking-scheme-comments +++ a/ipc/util.c @@ -17,12 +17,27 @@ * 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) + * rcu_read_lock() + * obtain the ipc object (kern_ipc_perm) by looking up the id in an idr + * tree. + * - perform initial checks (capabilities, auditing and permission, + * etc). + * - perform read-only operations, such as STAT, INFO commands. + * acquire the ipc lock (kern_ipc_perm.lock) through + * ipc_lock_object() + * - perform data updates, such as SET, RMID commands and + * mechanism-specific operations (semop/semtimedop, + * msgsnd/msgrcv, shmat/shmdt). + * drop the ipc lock, through ipc_unlock_object(). + * rcu_read_unlock() + * + * The ids->rwsem must be taken when: + * - creating, removing and iterating the existing entries in ipc + * identifier sets. + * - iterating through /proc/sysvipc/* files. + * + * Note that sems have a special fast path that avoids kern_ipc_perm.lock - + * see sem_lock(). */ #include <linux/mm.h> _ Patches currently in -mm which might be from davidlohr@xxxxxx are origin.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html