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Re: [Xen-devel] [PATCH v10 26/31] COLO proxy: implement setup/teardown of COLO proxy module

On 03/14/2016 05:13 PM, Wen Congyang wrote:

On 03/12/2016 06:25 AM, Konrad Rzeszutek Wilk wrote:

+extern int colo_proxy_setup(libxl__colo_proxy_state *cps);
+extern void colo_proxy_teardown(libxl__colo_proxy_state *cps);
  #endif
diff --git a/tools/libxl/libxl_colo_proxy.c b/tools/libxl/libxl_colo_proxy.c
new file mode 100644
index 0000000..e07e640
--- /dev/null
+++ b/tools/libxl/libxl_colo_proxy.c
@@ -0,0 +1,230 @@
+/*
+ * Copyright (C) 2015 FUJITSU LIMITED


2016?


Yes, I will check all new files.


+ * Author: Yang Hongyang <hongyang.yang@xxxxxxxxxxxx>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published
+ * by the Free Software Foundation; version 2.1 only. with the special
+ * exception on linking described in file LICENSE.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Lesser General Public License for more details.
+ */
+
+#include "libxl_osdeps.h" /* must come before any other headers */
+
+#include "libxl_internal.h"
+#include "libxl_colo.h"
+#include <linux/netlink.h>
+
+#define NETLINK_COLO 28


Can you include a comment why 28? Why not 31415?


OK, will add a comment to describe it.




+
+enum colo_netlink_op {
+    COLO_QUERY_CHECKPOINT = (NLMSG_MIN_TYPE + 1),
+    COLO_CHECKPOINT,
+    COLO_FAILOVER,
+    COLO_PROXY_INIT,
+    COLO_PROXY_RESET, /* UNUSED, will be used for continuous FT */
+};
+
+/* ========= colo-proxy: helper functions ========== */
+
+static int colo_proxy_send(libxl__colo_proxy_state *cps, uint8_t *buff,
+                           uint64_t size, int type)
+{
+    struct sockaddr_nl sa;
+    struct nlmsghdr msg;
+    struct iovec iov;
+    struct msghdr mh;
+    int ret;
+
+    STATE_AO_GC(cps->ao);
+
+    memset(&sa, 0, sizeof(sa));
+    sa.nl_family = AF_NETLINK;
+    sa.nl_pid = 0;
+    sa.nl_groups = 0;
+
+    msg.nlmsg_len = NLMSG_SPACE(0);
+    msg.nlmsg_flags = NLM_F_REQUEST;
+    if (type == COLO_PROXY_INIT) {
+        msg.nlmsg_flags |= NLM_F_ACK;
+    }


I don't think you need the { }?


Yes, will fix it in the next version.



Ah, yup:

5. Block structure

Every indented statement is braced apart from blocks that contain just
one statement.


+    msg.nlmsg_seq = 0;
+    /* This is untrusty */


Umm, can you be more specific pls?


+    msg.nlmsg_pid = cps->index;
+    msg.nlmsg_type = type;
+
+    iov.iov_base = &msg;
+    iov.iov_len = msg.nlmsg_len;
+
+    mh.msg_name = &sa;
+    mh.msg_namelen = sizeof(sa);
+    mh.msg_iov = &iov;
+    mh.msg_iovlen = 1;
+    mh.msg_control = NULL;
+    mh.msg_controllen = 0;
+    mh.msg_flags = 0;
+
+    ret = sendmsg(cps->sock_fd, &mh, 0);
+    if (ret <= 0) {
+        LOG(ERROR, "can't send msg to kernel by netlink: %s",
+            strerror(errno));
+    }
+
+    return ret;
+}
+
+/* error: return -1, otherwise return 0 */
+static int64_t colo_proxy_recv(libxl__colo_proxy_state *cps, uint8_t **buff,
+                               unsigned int timeout_us)
+{
+    struct sockaddr_nl sa;
+    struct iovec iov;
+    struct msghdr mh = {
+        .msg_name = &sa,
+        .msg_namelen = sizeof(sa),
+        .msg_iov = &iov,
+        .msg_iovlen = 1,
+    };
+    struct timeval tv;
+    uint32_t size = 16384;
+    int64_t len = 0;
+    int ret;
+
+    STATE_AO_GC(cps->ao);
+    uint8_t *tmp = libxl__malloc(NOGC, size);
+
+    if (timeout_us) {
+        tv.tv_sec = timeout_us / 1000000;
+        tv.tv_usec = timeout_us % 1000000;
+        setsockopt(cps->sock_fd, SOL_SOCKET, SO_RCVTIMEO, &tv, sizeof(tv));
+    }
+
+    iov.iov_base = tmp;
+    iov.iov_len = size;
+next:
+    ret = recvmsg(cps->sock_fd, &mh, 0);
+    if (ret <= 0) {
+        if (errno != EAGAIN && errno != EWOULDBLOCK)


-EINTR ?


IIRC, WAGAIN and EWOULDBLOCK may have different value in some system.
EINTR is not handled here.




+            LOGE(ERROR, "can't recv msg from kernel by netlink");
+        goto err;
+    }
+
+    len += ret;
+    if (mh.msg_flags & MSG_TRUNC) {
+        size += 16384;
+        tmp = libxl__realloc(NOGC, tmp, size);


You really should check 'tmp'.

If this loop continues on for some time the 'size' may be
in milions and this realloc will fail.
As i see from the code, libxl_realloc will invoke _exit(-1) if malloc failed, so we'll keep it. 

Thanks
        -Xie


OK, will fix it in the next version.




+        iov.iov_base = tmp + len;
+        iov.iov_len = size - len;
+        goto next;



+    }
+
+    *buff = tmp;
+    ret = len;
+    goto out;
+
+err:
+    free(tmp);
+    *buff = NULL;
+
+out:
+    if (timeout_us) {
+        tv.tv_sec = 0;
+        tv.tv_usec = 0;
+        setsockopt(cps->sock_fd, SOL_SOCKET, SO_RCVTIMEO, &tv, sizeof(tv));
+    }
+    return ret;
+}
+
+/* ========= colo-proxy: setup and teardown ========== */
+
+int colo_proxy_setup(libxl__colo_proxy_state *cps)
+{
+    int skfd = 0;
+    struct sockaddr_nl sa;
+    struct nlmsghdr *h;
+    int i = 1;
+    int ret = ERROR_FAIL;
+    uint8_t *buff = NULL;
+    int64_t size;
+
+    STATE_AO_GC(cps->ao);
+
+    skfd = socket(PF_NETLINK, SOCK_RAW, NETLINK_COLO);
+    if (skfd < 0) {
+        LOG(ERROR, "can not create a netlink socket: %s", strerror(errno));
+        goto out;
+    }
+    cps->sock_fd = skfd;
+    memset(&sa, 0, sizeof(sa));
+    sa.nl_family = AF_NETLINK;
+    sa.nl_groups = 0;
+retry:
+    sa.nl_pid = i++;
+
+    if (i > 10) {
+        LOG(ERROR, "netlink bind error");
+        goto out;
+    }
+
+    ret = bind(skfd, (struct sockaddr *)&sa, sizeof(sa));
+    if (ret < 0 && errno == EADDRINUSE) {
+        LOG(ERROR, "colo index %d has already in used", sa.nl_pid);
+        goto retry;
+    } else if (ret < 0) {
+        LOG(ERROR, "netlink bind error");
+        goto out;
+    }
+
+    cps->index = sa.nl_pid;
+    ret = colo_proxy_send(cps, NULL, 0, COLO_PROXY_INIT);
+    if (ret < 0) {
+        goto out;
+    }


Ditto. You can remove it.


OK, will check all codes.

Thanks
Wen Congyang




+    /* receive ack */
+    size = colo_proxy_recv(cps, &buff, 500000);
+    if (size < 0) {
+        LOG(ERROR, "Can't recv msg from kernel by netlink: %s",
+            strerror(errno));
+        goto out;
+    }
+
+    if (size) {
+        h = (struct nlmsghdr *)buff;
+        if (h->nlmsg_type == NLMSG_ERROR) {
+            /* ack's type is NLMSG_ERROR */
+            struct nlmsgerr *err = (struct nlmsgerr *)NLMSG_DATA(h);
+
+            if (size - sizeof(*h) < sizeof(*err)) {
+                LOG(ERROR, "NLMSG_LENGTH is too short");
+                goto out;
+            }
+
+            if (err->error) {
+                LOG(ERROR, "NLMSG_ERROR contains error %d", err->error);
+                goto out;
+            }
+        }
+    }
+
+    ret = 0;
+
+out:
+    free(buff);
+    if (ret) {
+        close(cps->sock_fd);
+        cps->sock_fd = -1;
+    }
+    return ret;
+}
+
+void colo_proxy_teardown(libxl__colo_proxy_state *cps)
+{
+    if (cps->sock_fd >= 0) {
+        close(cps->sock_fd);
+        cps->sock_fd = -1;
+    }
+}
diff --git a/tools/libxl/libxl_internal.h b/tools/libxl/libxl_internal.h
index 3af5fdd..3b44b09 100644
--- a/tools/libxl/libxl_internal.h
+++ b/tools/libxl/libxl_internal.h
@@ -3112,6 +3112,15 @@ libxl__stream_read_inuse(const libxl__stream_read_state 
*stream)
  }

  /*----- colo related state structure -----*/
+typedef struct libxl__colo_proxy_state libxl__colo_proxy_state;
+struct libxl__colo_proxy_state {
+    /* set by caller of colo_proxy_setup */
+    libxl__ao *ao;
+
+    int sock_fd;
+    int index;
+};
+
  typedef struct libxl__colo_save_state libxl__colo_save_state;
  struct libxl__colo_save_state {
      int send_fd;
@@ -3126,6 +3135,9 @@ struct libxl__colo_save_state {
      /* private, used by qdisk block replication */
      bool qdisk_used;
      bool qdisk_setuped;
+
+    /* private, used by colo-proxy */
+    libxl__colo_proxy_state cps;
  };

  /*----- Domain suspend (save) state structure -----*/
@@ -3535,6 +3547,9 @@ struct libxl__colo_restore_state {
      bool qdisk_setuped;
      const char *host;
      const char *port;
+
+    /* private, used by colo-proxy */
+    libxl__colo_proxy_state cps;
  };

  struct libxl__domain_create_state {
--
2.5.0






.



.





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