From 03f595668017f1a1fb971c02fc37140bc6e7bb1c Mon Sep 17 00:00:00 2001 From: Stanislav Kinsbursky Date: Fri, 4 Jan 2013 15:34:50 -0800 Subject: ipc: add sysctl to specify desired next object id Add 3 new variables and sysctls to tune them (by one "next_id" variable for messages, semaphores and shared memory respectively). This variable can be used to set desired id for next allocated IPC object. By default it's equal to -1 and old behaviour is preserved. If this variable is non-negative, then desired idr will be extracted from it and used as a start value to search for free IDR slot. Notes: 1) this patch doesn't guarantee that the new object will have desired id. So it's up to user space how to handle new object with wrong id. 2) After a sucessful id allocation attempt, "next_id" will be set back to -1 (if it was non-negative). [akpm@linux-foundation.org: checkpatch fixes] Signed-off-by: Stanislav Kinsbursky Cc: Serge Hallyn Cc: "Eric W. Biederman" Cc: Pavel Emelyanov Cc: Al Viro Cc: KOSAKI Motohiro Cc: Michael Kerrisk Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- ipc/util.h | 1 + 1 file changed, 1 insertion(+) (limited to 'ipc/util.h') diff --git a/ipc/util.h b/ipc/util.h index c8fe2f7631e9..a61e0ca2bffd 100644 --- a/ipc/util.h +++ b/ipc/util.h @@ -92,6 +92,7 @@ void __init ipc_init_proc_interface(const char *path, const char *header, #define IPC_SHM_IDS 2 #define ipcid_to_idx(id) ((id) % SEQ_MULTIPLIER) +#define ipcid_to_seqx(id) ((id) / SEQ_MULTIPLIER) /* must be called with ids->rw_mutex acquired for writing */ int ipc_addid(struct ipc_ids *, struct kern_ipc_perm *, int); -- cgit v1.2.3-59-g8ed1b