The size of requested per-task data can be bigger that the size of one
netlink skb. Currently we are able to split data into a few netlink
messages.
v2: set NLM_F_MULTI for multipart packets
Signed-off-by: Andrey Vagin <ava...@openvz.org>
---
kernel/taskdiag.c | 76 +++++++++++++++++++++++++++++++++++++------------------
1 file changed, 51 insertions(+), 25 deletions(-)
diff --git a/kernel/taskdiag.c b/kernel/taskdiag.c
index 3497304..5771baf 100644
--- a/kernel/taskdiag.c
+++ b/kernel/taskdiag.c
@@ -84,13 +84,21 @@ static int fill_task_base(struct task_struct *p, struct
sk_buff *skb)
}
static int task_diag_fill(struct task_struct *tsk, struct sk_buff *skb,
- u64 show_flags, u32 portid, u32 seq)
+ u64 show_flags, u32 portid, u32 seq,
+ struct netlink_callback *cb)
{
void *reply;
- int err;
+ int err = 0, i = 0, n = 0;
+ int flags = 0;
u32 pid;
- reply = genlmsg_put(skb, portid, seq, &taskstats_family, 0,
TASK_DIAG_CMD_GET);
+ if (cb) {
+ n = cb->args[2];
+ flags |= NLM_F_MULTI;
+ }
+
+ reply = genlmsg_put(skb, portid, seq, &taskstats_family,
+ flags, TASK_DIAG_CMD_GET);
if (reply == NULL)
return -EMSGSIZE;
@@ -100,15 +108,26 @@ static int task_diag_fill(struct task_struct *tsk, struct
sk_buff *skb,
goto err;
if (show_flags & TASK_DIAG_SHOW_BASE) {
- err = fill_task_base(tsk, skb);
+ if (i >= n)
+ err = fill_task_base(tsk, skb);
if (err)
goto err;
+ i++;
}
genlmsg_end(skb, reply);
+ if (cb)
+ cb->args[2] = 0;
+
return 0;
err:
- genlmsg_cancel(skb, reply);
+ if (err == -EMSGSIZE && i != 0) {
+ if (cb)
+ cb->args[2] = i;
+ genlmsg_end(skb, reply);
+ } else
+ genlmsg_cancel(skb, reply);
+
return err;
}
@@ -138,7 +157,7 @@ int taskdiag_dumpit(struct sk_buff *skb, struct
netlink_callback *cb)
continue;
rc = task_diag_fill(iter.task, skb, req.show_flags,
- NETLINK_CB(cb->skb).portid, cb->nlh->nlmsg_seq);
+ NETLINK_CB(cb->skb).portid, cb->nlh->nlmsg_seq,
cb);
if (rc < 0) {
put_task_struct(iter.task);
if (rc != -EMSGSIZE)
@@ -157,7 +176,7 @@ int taskdiag_doit(struct sk_buff *skb, struct genl_info
*info)
struct nlattr *nla = info->attrs[TASK_DIAG_CMD_ATTR_GET];
struct task_struct *tsk = NULL;
struct task_diag_pid req;
- struct sk_buff *msg;
+ struct sk_buff *msg = NULL;
size_t size;
int rc;
@@ -174,35 +193,42 @@ int taskdiag_doit(struct sk_buff *skb, struct genl_info
*info)
*/
memcpy(&req, nla_data(nla), sizeof(req));
- size = taskdiag_packet_size(req.show_flags);
- msg = genlmsg_new(size, GFP_KERNEL);
- if (!msg)
- return -ENOMEM;
-
rcu_read_lock();
tsk = find_task_by_vpid(req.pid);
if (tsk)
get_task_struct(tsk);
rcu_read_unlock();
- if (!tsk) {
- rc = -ESRCH;
- goto err;
- };
+ if (!tsk)
+ return -ESRCH;
if (!ptrace_may_access(tsk, PTRACE_MODE_READ)) {
put_task_struct(tsk);
- rc = -EPERM;
- goto err;
+ return -EPERM;
+ }
+
+ size = taskdiag_packet_size(req.show_flags);
+
+ while (1) {
+ msg = genlmsg_new(size, GFP_KERNEL);
+ if (!msg) {
+ put_task_struct(tsk);
+ return -EMSGSIZE;
+ }
+
+ rc = task_diag_fill(tsk, msg, req.show_flags,
+ info->snd_portid, info->snd_seq, NULL);
+ if (rc != -EMSGSIZE)
+ break;
+
+ nlmsg_free(msg);
+ size += 128;
}
- rc = task_diag_fill(tsk, msg, req.show_flags,
- info->snd_portid, info->snd_seq);
put_task_struct(tsk);
- if (rc < 0)
- goto err;
+ if (rc < 0) {
+ nlmsg_free(msg);
+ return rc;
+ }
return genlmsg_reply(msg, info);
-err:
- nlmsg_free(msg);
- return rc;
}
--
2.1.0
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