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authorDenis V. Lunev <den@openvz.org>2007-10-10 21:15:29 -0700
committerDavid S. Miller <davem@davemloft.net>2007-10-10 21:15:29 -0700
commitcd40b7d3983c708aabe3d3008ec64ffce56d33b0 (patch)
tree0d6fe9cfd2f03fdeee126e317d4bfb145afc458d /drivers/scsi
parentaed815601f3f95281ab3a01f7e2cbe1bd54285a0 (diff)
downloadlinux-cd40b7d3983c708aabe3d3008ec64ffce56d33b0.tar.bz2
[NET]: make netlink user -> kernel interface synchronious
This patch make processing netlink user -> kernel messages synchronious. This change was inspired by the talk with Alexey Kuznetsov about current netlink messages processing. He says that he was badly wrong when introduced asynchronious user -> kernel communication. The call netlink_unicast is the only path to send message to the kernel netlink socket. But, unfortunately, it is also used to send data to the user. Before this change the user message has been attached to the socket queue and sk->sk_data_ready was called. The process has been blocked until all pending messages were processed. The bad thing is that this processing may occur in the arbitrary process context. This patch changes nlk->data_ready callback to get 1 skb and force packet processing right in the netlink_unicast. Kernel -> user path in netlink_unicast remains untouched. EINTR processing for in netlink_run_queue was changed. It forces rtnl_lock drop, but the process remains in the cycle until the message will be fully processed. So, there is no need to use this kludges now. Signed-off-by: Denis V. Lunev <den@openvz.org> Acked-by: Alexey Kuznetsov <kuznet@ms2.inr.ac.ru> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'drivers/scsi')
-rw-r--r--drivers/scsi/scsi_netlink.c25
-rw-r--r--drivers/scsi/scsi_transport_iscsi.c82
2 files changed, 37 insertions, 70 deletions
diff --git a/drivers/scsi/scsi_netlink.c b/drivers/scsi/scsi_netlink.c
index 163acf6ad2d3..40579edca101 100644
--- a/drivers/scsi/scsi_netlink.c
+++ b/drivers/scsi/scsi_netlink.c
@@ -64,7 +64,7 @@ scsi_nl_rcv_msg(struct sk_buff *skb)
if (nlh->nlmsg_type != SCSI_TRANSPORT_MSG) {
err = -EBADMSG;
- goto next_msg;
+ return;
}
hdr = NLMSG_DATA(nlh);
@@ -99,27 +99,6 @@ next_msg:
/**
- * scsi_nl_rcv_msg -
- * Receive handler for a socket. Extracts a received message buffer from
- * the socket, and starts message processing.
- *
- * @sk: socket
- * @len: unused
- *
- **/
-static void
-scsi_nl_rcv(struct sock *sk, int len)
-{
- struct sk_buff *skb;
-
- while ((skb = skb_dequeue(&sk->sk_receive_queue))) {
- scsi_nl_rcv_msg(skb);
- kfree_skb(skb);
- }
-}
-
-
-/**
* scsi_nl_rcv_event -
* Event handler for a netlink socket.
*
@@ -168,7 +147,7 @@ scsi_netlink_init(void)
}
scsi_nl_sock = netlink_kernel_create(&init_net, NETLINK_SCSITRANSPORT,
- SCSI_NL_GRP_CNT, scsi_nl_rcv, NULL,
+ SCSI_NL_GRP_CNT, scsi_nl_rcv_msg, NULL,
THIS_MODULE);
if (!scsi_nl_sock) {
printk(KERN_ERR "%s: register of recieve handler failed\n",
diff --git a/drivers/scsi/scsi_transport_iscsi.c b/drivers/scsi/scsi_transport_iscsi.c
index 4916f01230dc..5428d15f23c6 100644
--- a/drivers/scsi/scsi_transport_iscsi.c
+++ b/drivers/scsi/scsi_transport_iscsi.c
@@ -1097,61 +1097,49 @@ iscsi_if_recv_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
}
/*
- * Get message from skb (based on rtnetlink_rcv_skb). Each message is
- * processed by iscsi_if_recv_msg. Malformed skbs with wrong lengths or
- * invalid creds are discarded silently.
+ * Get message from skb. Each message is processed by iscsi_if_recv_msg.
+ * Malformed skbs with wrong lengths or invalid creds are not processed.
*/
static void
-iscsi_if_rx(struct sock *sk, int len)
+iscsi_if_rx(struct sk_buff *skb)
{
- struct sk_buff *skb;
-
mutex_lock(&rx_queue_mutex);
- while ((skb = skb_dequeue(&sk->sk_receive_queue)) != NULL) {
- if (NETLINK_CREDS(skb)->uid) {
- skb_pull(skb, skb->len);
- goto free_skb;
+ while (skb->len >= NLMSG_SPACE(0)) {
+ int err;
+ uint32_t rlen;
+ struct nlmsghdr *nlh;
+ struct iscsi_uevent *ev;
+
+ nlh = nlmsg_hdr(skb);
+ if (nlh->nlmsg_len < sizeof(*nlh) ||
+ skb->len < nlh->nlmsg_len) {
+ break;
}
- while (skb->len >= NLMSG_SPACE(0)) {
- int err;
- uint32_t rlen;
- struct nlmsghdr *nlh;
- struct iscsi_uevent *ev;
+ ev = NLMSG_DATA(nlh);
+ rlen = NLMSG_ALIGN(nlh->nlmsg_len);
+ if (rlen > skb->len)
+ rlen = skb->len;
- nlh = nlmsg_hdr(skb);
- if (nlh->nlmsg_len < sizeof(*nlh) ||
- skb->len < nlh->nlmsg_len) {
- break;
- }
-
- ev = NLMSG_DATA(nlh);
- rlen = NLMSG_ALIGN(nlh->nlmsg_len);
- if (rlen > skb->len)
- rlen = skb->len;
-
- err = iscsi_if_recv_msg(skb, nlh);
- if (err) {
- ev->type = ISCSI_KEVENT_IF_ERROR;
- ev->iferror = err;
- }
- do {
- /*
- * special case for GET_STATS:
- * on success - sending reply and stats from
- * inside of if_recv_msg(),
- * on error - fall through.
- */
- if (ev->type == ISCSI_UEVENT_GET_STATS && !err)
- break;
- err = iscsi_if_send_reply(
- NETLINK_CREDS(skb)->pid, nlh->nlmsg_seq,
- nlh->nlmsg_type, 0, 0, ev, sizeof(*ev));
- } while (err < 0 && err != -ECONNREFUSED);
- skb_pull(skb, rlen);
+ err = iscsi_if_recv_msg(skb, nlh);
+ if (err) {
+ ev->type = ISCSI_KEVENT_IF_ERROR;
+ ev->iferror = err;
}
-free_skb:
- kfree_skb(skb);
+ do {
+ /*
+ * special case for GET_STATS:
+ * on success - sending reply and stats from
+ * inside of if_recv_msg(),
+ * on error - fall through.
+ */
+ if (ev->type == ISCSI_UEVENT_GET_STATS && !err)
+ break;
+ err = iscsi_if_send_reply(
+ NETLINK_CREDS(skb)->pid, nlh->nlmsg_seq,
+ nlh->nlmsg_type, 0, 0, ev, sizeof(*ev));
+ } while (err < 0 && err != -ECONNREFUSED);
+ skb_pull(skb, rlen);
}
mutex_unlock(&rx_queue_mutex);
}