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Subject[RFC v17][PATCH 12/60] pids 2/7: Have alloc_pidmap() return actual error code
Date
From: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>

alloc_pidmap() can fail either because all pid numbers are in use or
because memory allocation failed. With support for setting a specific
pid number, alloc_pidmap() would also fail if either the given pid
number is invalid or in use.

Rather than have callers assume -ENOMEM, have alloc_pidmap() return
the actual error.

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/fork.c | 5 +++--
kernel/pid.c | 9 ++++++---
2 files changed, 9 insertions(+), 5 deletions(-)

diff --git a/kernel/fork.c b/kernel/fork.c
index bd29592..e90cee5 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1123,10 +1123,11 @@ static struct task_struct *copy_process(unsigned long clone_flags,
goto bad_fork_cleanup_io;

if (pid != &init_struct_pid) {
- retval = -ENOMEM;
pid = alloc_pid(p->nsproxy->pid_ns);
- if (!pid)
+ if (IS_ERR(pid)) {
+ retval = PTR_ERR(pid);
goto bad_fork_cleanup_io;
+ }

if (clone_flags & CLONE_NEWPID) {
retval = pid_ns_prepare_proc(p->nsproxy->pid_ns);
diff --git a/kernel/pid.c b/kernel/pid.c
index f618096..9c678ce 100644
--- a/kernel/pid.c
+++ b/kernel/pid.c
@@ -158,6 +158,7 @@ static int alloc_pidmap(struct pid_namespace *pid_ns)
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;
+ rc = -EAGAIN;
for (i = 0; i <= max_scan; ++i) {
rc = alloc_pidmap_page(map);
if (rc)
@@ -188,12 +189,14 @@ static int alloc_pidmap(struct pid_namespace *pid_ns)
} else {
map = &pid_ns->pidmap[0];
offset = RESERVED_PIDS;
- if (unlikely(last == offset))
+ if (unlikely(last == offset)) {
+ rc = -EAGAIN;
break;
+ }
}
pid = mk_pid(pid_ns, map, offset);
}
- return -1;
+ return rc;
}

int next_pidmap(struct pid_namespace *pid_ns, int last)
@@ -298,7 +301,7 @@ out_free:
free_pidmap(pid->numbers + i);

kmem_cache_free(ns->pid_cachep, pid);
- pid = NULL;
+ pid = ERR_PTR(nr);
goto out;
}

--
1.6.0.4


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