[PATCH 3.13 161/187] RDMA/iwcm: Use a default listen backlog if needed

Kamal Mostafa
2014-09-15T22:14:53Z

From: Steve Wise <swise@opengridcomputing.com>

commit 2f0304d21867476394cd51a54e97f7273d112261 upstream.

If the user creates a listening cm_id with backlog of 0 the IWCM ends
up not allowing any connection requests at all. The correct behavior
is for the IWCM to pick a default value if the user backlog parameter
is zero.

Lustre from version 1.8.8 onward uses a backlog of 0, which breaks
iwarp support without this fix.

Signed-off-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
---
drivers/infiniband/core/iwcm.c | 27 +++++++++++++++++++++++++++
1 file changed, 27 insertions(+)

diff --git a/drivers/infiniband/core/iwcm.c b/drivers/infiniband/core/iwcm.c
index 0717940..a86b6ca 100644
--- a/drivers/infiniband/core/iwcm.c
+++ b/drivers/infiniband/core/iwcm.c
@@ -46,6 +46,7 @@
#include <linux/completion.h>
#include <linux/slab.h>
#include <linux/module.h>
+#include <linux/sysctl.h>

#include <rdma/iw_cm.h>
#include <rdma/ib_addr.h>
@@ -65,6 +66,20 @@ struct iwcm_work {
struct list_head free_list;
};

+static unsigned int default_backlog = 256;
+
+static struct ctl_table_header *iwcm_ctl_table_hdr;
+static struct ctl_table iwcm_ctl_table[] = {
+ {
+ .procname = "default_backlog",
+ .data = &default_backlog,
+ .maxlen = sizeof(default_backlog),
+ .mode = 0644,
+ .proc_handler = proc_dointvec,
+ },
+ { }
+};
+
/*
* The following services provide a mechanism for pre-allocating iwcm_work
* elements. The design pre-allocates them based on the cm_id type:
@@ -426,6 +441,9 @@ int iw_cm_listen(struct iw_cm_id *cm_id, int backlog)

cm_id_priv = container_of(cm_id, struct iwcm_id_private, id);

+ if (!backlog)
+ backlog = default_backlog;
+
ret = alloc_work_entries(cm_id_priv, backlog);
if (ret)
return ret;
@@ -1031,11 +1049,20 @@ static int __init iw_cm_init(void)
if (!iwcm_wq)
return -ENOMEM;

+ iwcm_ctl_table_hdr = register_net_sysctl(&init_net, "net/iw_cm",
+ iwcm_ctl_table);
+ if (!iwcm_ctl_table_hdr) {
+ pr_err("iw_cm: couldn't register sysctl paths\n");
+ destroy_workqueue(iwcm_wq);
+ return -ENOMEM;
+ }
+
return 0;
}

static void __exit iw_cm_cleanup(void)
{
+ unregister_net_sysctl_table(iwcm_ctl_table_hdr);
destroy_workqueue(iwcm_wq);
}

--
1.9.1