Messages in this thread Patch in this message | | | Date | Thu, 6 Aug 2009 23:13:04 -0700 | From | Sukadev Bhattiprolu <> | Subject | [RFC][v4][PATCH 3/7]: Add target_pid parameter to alloc_pidmap() |
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Subject: [RFC][v4][PATCH 3/7]: Add target_pid parameter to alloc_pidmap()
With support for setting a specific pid number for a process, alloc_pidmap() will need a 'target_pid' parameter.
Changelog[v2]: - (Serge Hallyn) Check for 'pid < 0' in set_pidmap().(Code actually checks for 'pid <= 0' for completeness).
Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com> Acked-by: Serge Hallyn <serue@us.ibm.com> Reviewed-by: Oren Laadan <orenl@cs.columbia.edu> --- kernel/pid.c | 28 ++++++++++++++++++++++++++-- 1 files changed, 26 insertions(+), 2 deletions(-)
Index: linux-2.6/kernel/pid.c =================================================================== --- linux-2.6.orig/kernel/pid.c 2009-08-05 17:02:45.000000000 -0700 +++ linux-2.6/kernel/pid.c 2009-08-05 19:34:37.000000000 -0700 @@ -147,11 +147,35 @@ return 0; } -static int alloc_pidmap(struct pid_namespace *pid_ns) +static int set_pidmap(struct pid_namespace *pid_ns, int pid) +{ + int offset; + struct pidmap *map; + + if (pid <= 0 || pid >= pid_max) + return -EINVAL; + + offset = pid & BITS_PER_PAGE_MASK; + map = &pid_ns->pidmap[pid/BITS_PER_PAGE]; + + if (alloc_pidmap_page(map)) + return -ENOMEM; + + if (test_and_set_bit(offset, map->page)) + return -EBUSY; + + atomic_dec(&map->nr_free); + return pid; +} + +static int alloc_pidmap(struct pid_namespace *pid_ns, int target_pid) { int i, rc, offset, max_scan, pid, last = pid_ns->last_pid; struct pidmap *map; + if (target_pid) + return set_pidmap(pid_ns, target_pid); + pid = last + 1; if (pid >= pid_max) pid = RESERVED_PIDS; @@ -270,7 +294,7 @@ tmp = ns; for (i = ns->level; i >= 0; i--) { - nr = alloc_pidmap(tmp); + nr = alloc_pidmap(tmp, 0); if (nr < 0) goto out_free;
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