I write a simple kernel module which include the following ksocket connection accept codes:
.....(some ksocket initiation)
while( on_service )
{
sockfd_c = kaccept(sockfd_s, (struct sockaddr *)&addr_cli, &addr_len);
kclose(sockfd_c);
}
And write a simple client to connect to this socket server. From console, I found the memory usage is increasing by "free" command when I continuously run the client connection.
The functions of kaccept() and kclose() are as follows.
int kclose(ksocket_t sockfd)
{
struct socket *sk;
int ret;
sk = (struct socket *)sockfd;
ret = sk->ops->release(sk);
if (sk)
{
sock_release(sk);
}
return ret;
}
ksocket_t kaccept(ksocket_t socket, struct sockaddr *address, int *address_len)
{
struct socket *sk;
struct socket *new_sk = NULL;
int ret;
sk = (struct socket *)socket;
sxg_debug("family = %d, type = %d, protocol = %d\n",
sk->sk->sk_family, sk->type, sk->sk->sk_protocol);
//new_sk = sock_alloc();
//sock_alloc() is not exported, so i use sock_create() instead
ret = sock_create(sk->sk->sk_family, sk->type, sk->sk->sk_protocol, &new_sk);
if (ret < 0)
return NULL;
if (!new_sk)
return NULL;
new_sk->type = sk->type;
new_sk->ops = sk->ops;
ret = sk->ops->accept(sk, new_sk, 0 /*sk->file->f_flags*/);
if (ret < 0)
goto error_kaccept;
if (address)
{
ret = new_sk->ops->getname(new_sk, address, address_len, 2);
if (ret < 0)
goto error_kaccept;
}
return new_sk;
error_kaccept:
sock_release(new_sk);
return NULL;
}
Does there anybody know why/how the memory leak?
Use valgrind
to find memory leaks
as
valgrind ./your_program
My kernel version is 3.2 and I am trying to write a kernel socket server. After several days' fighting, I have the following finding.
I user sock_create() to create a socket server and then listen and accept connection by
sockfd_srv = sock_create(...)
...
while(1) {
sockfd_srv->ops->listen();
sockfd_cli = sock_create(...);
sockfd_srv->ops->accept(..., &sockfd_cli);
....(do something)
sock_release(sockfd_cli);
}
The above program will cause the memory leak even I DO release clients' socket by sock_release(). Finally, the system will be out of memory.
I change it as follows where I use sock_create_lite() instead of sock_create().
sockfd_srv = sock_create(...)
...
while(1) {
sockfd_srv->ops->listen();
sockfd_cli = sock_create_lite(...);
sockfd_srv->ops->accept(..., &sockfd_cli);
....(do something)
sock_release(sockfd_cli);
}
Then the memory leak problem is gone.
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