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Subject[PATCH 54/62] ipc: convert to idr_alloc()
Date
Convert to the much saner new idr interface.

The new interface doesn't directly translate to the way idr_pre_get()
was used around ipc_addid() as preloading disables preemption. From
my cursory reading, it seems like we should be able to do all
allocation from ipc_addid(), so I moved it there. Can you please
check whether this would be okay? If this is wrong and ipc_addid()
should be allowed to be called from non-sleepable context, I'd suggest
allocating id itself in the outer functions and later install the
pointer using idr_replace().

Only compile tested.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Stanislav Kinsbursky <skinsbursky@parallels.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: James Morris <jmorris@namei.org>
---
This patch depends on an earlier idr changes and I think it would be
best to route these together through -mm. Please holler if there's
any objection. Thanks.

ipc/util.c | 30 ++++++++++--------------------
1 file changed, 10 insertions(+), 20 deletions(-)

diff --git a/ipc/util.c b/ipc/util.c
index 74e1d9c..91ce0bc 100644
--- a/ipc/util.c
+++ b/ipc/util.c
@@ -252,7 +252,7 @@ int ipc_addid(struct ipc_ids* ids, struct kern_ipc_perm* new, int size)
{
kuid_t euid;
kgid_t egid;
- int id, err;
+ int id;
int next_id = ids->next_id;

if (size > IPCMNI)
@@ -261,17 +261,21 @@ int ipc_addid(struct ipc_ids* ids, struct kern_ipc_perm* new, int size)
if (ids->in_use >= size)
return -ENOSPC;

+ idr_preload(GFP_KERNEL);
+
spin_lock_init(&new->lock);
new->deleted = 0;
rcu_read_lock();
spin_lock(&new->lock);

- err = idr_get_new_above(&ids->ipcs_idr, new,
- (next_id < 0) ? 0 : ipcid_to_idx(next_id), &id);
- if (err) {
+ id = idr_alloc(&ids->ipcs_idr, new,
+ (next_id < 0) ? 0 : ipcid_to_idx(next_id), 0,
+ GFP_NOWAIT);
+ idr_preload_end();
+ if (id < 0) {
spin_unlock(&new->lock);
rcu_read_unlock();
- return err;
+ return id;
}

ids->in_use++;
@@ -307,19 +311,10 @@ static int ipcget_new(struct ipc_namespace *ns, struct ipc_ids *ids,
struct ipc_ops *ops, struct ipc_params *params)
{
int err;
-retry:
- err = idr_pre_get(&ids->ipcs_idr, GFP_KERNEL);
-
- if (!err)
- return -ENOMEM;

down_write(&ids->rw_mutex);
err = ops->getnew(ns, params);
up_write(&ids->rw_mutex);
-
- if (err == -EAGAIN)
- goto retry;
-
return err;
}

@@ -375,9 +370,7 @@ static int ipcget_public(struct ipc_namespace *ns, struct ipc_ids *ids,
{
struct kern_ipc_perm *ipcp;
int flg = params->flg;
- int err;
-retry:
- err = idr_pre_get(&ids->ipcs_idr, GFP_KERNEL);
+ int err = 0;

/*
* Take the lock as a writer since we are potentially going to add
@@ -413,9 +406,6 @@ retry:
}
up_write(&ids->rw_mutex);

- if (err == -EAGAIN)
- goto retry;
-
return err;
}

--
1.8.1


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