On Tue, Jan 29, 2008 at 05:02:38PM +0100, [EMAIL PROTECTED] wrote: > This patch provides three new API to change the ID of an existing > System V IPCs. > > These APIs are: > long msg_chid(struct ipc_namespace *ns, int id, int newid); > long sem_chid(struct ipc_namespace *ns, int id, int newid); > long shm_chid(struct ipc_namespace *ns, int id, int newid); > > They return 0 or an error code in case of failure. > > They may be useful for setting a specific ID for an IPC when preparing > a restart operation. > > To be successful, the following rules must be respected: > - the IPC exists (of course...) > - the new ID must satisfy the ID computation rule. > - the entry in the idr corresponding to the new ID must be free.
> ipc/util.c | 48 ++++++++++++++++++++++++++++++++++++++++++++++++ > ipc/util.h | 1 + > 8 files changed, 197 insertions(+) For the record, OpenVZ uses "create with predefined ID" method which leads to less code. For example, change at the end is all we want from ipc/util.c . Also, if ids were A and B at the moment of checkpoint, and during restart they became B and A you'll get collision in both ways which you techically can avoid by classic "tmp = A, A = B, B = tmp" but you also can avoid all other loops just by creating with ID you need. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
