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authorStanislav Kinsbursky <skinsbursky@parallels.com>2013-01-04 15:34:50 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2013-01-04 16:11:45 -0800
commit03f595668017f1a1fb971c02fc37140bc6e7bb1c (patch)
tree3aa5c4b32b5fd396f0d74679548de8c09ca195a1 /ipc/util.h
parent9afdacda0252fc1ddb7907728e878518edbcdfce (diff)
downloadlinux-sh-03f595668017f1a1fb971c02fc37140bc6e7bb1c.tar.gz
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 <skinsbursky@parallels.com> Cc: Serge Hallyn <serge.hallyn@canonical.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Pavel Emelyanov <xemul@parallels.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Michael Kerrisk <mtk.manpages@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'ipc/util.h')
-rw-r--r--ipc/util.h1
1 files changed, 1 insertions, 0 deletions
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);