Cc: LKML
Sukadev Bhattiprolu [sukadev@xxxxxxxxxxxxxxxxxx] wrote:
|
| Subject: [v12][PATCH 3/9] Define set_pidmap() function
|
| Define a set_pidmap() interface which is like alloc_pidmap() only that
| caller specifies the pid number to be assigned.
|
| Changelog[v9]:
| - Completely rewrote this patch based on Eric Biederman's code.
| Changelog[v7]:
| - [Eric Biederman] Generalize alloc_pidmap() to take a range of pids.
| Changelog[v6]:
| - Separate target_pid > 0 case to minimize the number of checks needed.
| Changelog[v3]:
| - (Eric Biederman): Avoid set_pidmap() function. Added couple of
| checks for target_pid in alloc_pidmap() itself.
| 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@xxxxxxxxxx>
| Acked-by: Oren Laadan <orenl@xxxxxxxxxxxxxxx>
| ---
| kernel/pid.c | 41 +++++++++++++++++++++++++++++++++--------
| 1 files changed, 33 insertions(+), 8 deletions(-)
|
| diff --git a/kernel/pid.c b/kernel/pid.c
| index c4d9914..afef766 100644
| --- a/kernel/pid.c
| +++ b/kernel/pid.c
| @@ -147,18 +147,19 @@ static int alloc_pidmap_page(struct pidmap *map)
| return 0;
| }
|
| -static int alloc_pidmap(struct pid_namespace *pid_ns)
| +static int do_alloc_pidmap(struct pid_namespace *pid_ns, int last, int min,
| + int max)
| {
| - int i, offset, max_scan, pid, last = pid_ns->last_pid;
| + int i, offset, max_scan, pid;
| int rc = -EAGAIN;
| struct pidmap *map;
|
| pid = last + 1;
| if (pid >= pid_max)
| - pid = RESERVED_PIDS;
| + pid = min;
| offset = pid & BITS_PER_PAGE_MASK;
| map = &pid_ns->pidmap[pid/BITS_PER_PAGE];
| - max_scan = (pid_max + BITS_PER_PAGE - 1)/BITS_PER_PAGE - !offset;
| + max_scan = (max + BITS_PER_PAGE - 1)/BITS_PER_PAGE - !offset;
| for (i = 0; i <= max_scan; ++i) {
| rc = alloc_pidmap_page(map);
| if (rc)
| @@ -168,7 +169,6 @@ static int alloc_pidmap(struct pid_namespace *pid_ns)
| do {
| if (!test_and_set_bit(offset, map->page)) {
| atomic_dec(&map->nr_free);
| - pid_ns->last_pid = pid;
| return pid;
| }
| offset = find_next_offset(map, offset);
| @@ -179,16 +179,16 @@ static int alloc_pidmap(struct pid_namespace *pid_ns)
| * bitmap block and the final block was the same
| * as the starting point, pid is before last_pid.
| */
| - } while (offset < BITS_PER_PAGE && pid < pid_max &&
| + } while (offset < BITS_PER_PAGE && pid < max &&
| (i != max_scan || pid < last ||
| !((last+1) & BITS_PER_PAGE_MASK)));
| }
| - if (map < &pid_ns->pidmap[(pid_max-1)/BITS_PER_PAGE]) {
| + if (map < &pid_ns->pidmap[(max-1)/BITS_PER_PAGE]) {
| ++map;
| offset = 0;
| } else {
| map = &pid_ns->pidmap[0];
| - offset = RESERVED_PIDS;
| + offset = min;
| if (unlikely(last == offset)) {
| rc = -EAGAIN;
| break;
| @@ -199,6 +199,31 @@ static int alloc_pidmap(struct pid_namespace *pid_ns)
| return rc;
| }
|
| +static int alloc_pidmap(struct pid_namespace *pid_ns)
| +{
| + int nr;
| +
| + nr = do_alloc_pidmap(pid_ns, pid_ns->last_pid, RESERVED_PIDS, pid_max);
| + if (nr >= 0)
| + pid_ns->last_pid = nr;
| + return nr;
| +}
| +
| +static int set_pidmap(struct pid_namespace *pid_ns, int target)
| +{
| + if (!target)
| + return alloc_pidmap(pid_ns);
| +
| + if (target >= pid_max)
| + return -EINVAL;
| +
| + if ((target < 0) || (target < RESERVED_PIDS &&
| + pid_ns->last_pid >= RESERVED_PIDS))
| + return -EINVAL;
| +
| + return do_alloc_pidmap(pid_ns, target - 1, target, target + 1);
| +}
| +
| int next_pidmap(struct pid_namespace *pid_ns, int last)
| {
| int offset;
| --
| 1.6.0.4
|
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