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authorSagi Grimberg <sagig@mellanox.com>2014-04-29 13:13:45 +0300
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2014-06-07 13:25:38 -0700
commit8a2629ad0ba7902262df7ae980265d8f93e2dfc2 (patch)
tree35b0e8836946854ebf8c52112fd5142dec71856c
parent5de94f8f4acfce3ff79592cb1d6c58ae6c0b420e (diff)
downloadlinux-linaro-stable-8a2629ad0ba7902262df7ae980265d8f93e2dfc2.tar.gz
Target/iser: Fix iscsit_accept_np and rdma_cm racy flow
commit 531b7bf4bd795d9a09eac92504322a472c010bc8 upstream. RDMA CM and iSCSI target flows are asynchronous and completely uncorrelated. Relying on the fact that iscsi_accept_np will be called after CM connection request event and will wait for it is a mistake. When attempting to login to a few targets this flow is racy and unpredictable, but for parallel login to dozens of targets will race and hang every time. The correct synchronizing mechanism in this case is pending on a semaphore rather than a wait_for_event. We keep the pending interruptible for iscsi_np cleanup stage. (Squash patch to remove dead code into parent - nab) Reported-by: Slava Shwartsman <valyushash@gmail.com> Signed-off-by: Sagi Grimberg <sagig@mellanox.com> Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--drivers/infiniband/ulp/isert/ib_isert.c25
-rw-r--r--drivers/infiniband/ulp/isert/ib_isert.h2
2 files changed, 7 insertions, 20 deletions
diff --git a/drivers/infiniband/ulp/isert/ib_isert.c b/drivers/infiniband/ulp/isert/ib_isert.c
index f0f7187c839c..988e29d18bb4 100644
--- a/drivers/infiniband/ulp/isert/ib_isert.c
+++ b/drivers/infiniband/ulp/isert/ib_isert.c
@@ -27,6 +27,7 @@
#include <target/target_core_base.h>
#include <target/target_core_fabric.h>
#include <target/iscsi/iscsi_transport.h>
+#include <linux/semaphore.h>
#include "isert_proto.h"
#include "ib_isert.h"
@@ -462,8 +463,8 @@ isert_connect_request(struct rdma_cm_id *cma_id, struct rdma_cm_event *event)
list_add_tail(&isert_conn->conn_accept_node, &isert_np->np_accept_list);
mutex_unlock(&isert_np->np_accept_mutex);
- pr_debug("isert_connect_request() waking up np_accept_wq: %p\n", np);
- wake_up(&isert_np->np_accept_wq);
+ pr_debug("isert_connect_request() up np_sem np: %p\n", np);
+ up(&isert_np->np_sem);
return 0;
out_conn_dev:
@@ -2042,7 +2043,7 @@ isert_setup_np(struct iscsi_np *np,
pr_err("Unable to allocate struct isert_np\n");
return -ENOMEM;
}
- init_waitqueue_head(&isert_np->np_accept_wq);
+ sema_init(&isert_np->np_sem, 0);
mutex_init(&isert_np->np_accept_mutex);
INIT_LIST_HEAD(&isert_np->np_accept_list);
init_completion(&isert_np->np_login_comp);
@@ -2091,18 +2092,6 @@ out:
}
static int
-isert_check_accept_queue(struct isert_np *isert_np)
-{
- int empty;
-
- mutex_lock(&isert_np->np_accept_mutex);
- empty = list_empty(&isert_np->np_accept_list);
- mutex_unlock(&isert_np->np_accept_mutex);
-
- return empty;
-}
-
-static int
isert_rdma_accept(struct isert_conn *isert_conn)
{
struct rdma_cm_id *cm_id = isert_conn->conn_cm_id;
@@ -2186,16 +2175,14 @@ isert_accept_np(struct iscsi_np *np, struct iscsi_conn *conn)
int max_accept = 0, ret;
accept_wait:
- ret = wait_event_interruptible(isert_np->np_accept_wq,
- !isert_check_accept_queue(isert_np) ||
- np->np_thread_state == ISCSI_NP_THREAD_RESET);
+ ret = down_interruptible(&isert_np->np_sem);
if (max_accept > 5)
return -ENODEV;
spin_lock_bh(&np->np_thread_lock);
if (np->np_thread_state == ISCSI_NP_THREAD_RESET) {
spin_unlock_bh(&np->np_thread_lock);
- pr_err("ISCSI_NP_THREAD_RESET for isert_accept_np\n");
+ pr_debug("ISCSI_NP_THREAD_RESET for isert_accept_np\n");
return -ENODEV;
}
spin_unlock_bh(&np->np_thread_lock);
diff --git a/drivers/infiniband/ulp/isert/ib_isert.h b/drivers/infiniband/ulp/isert/ib_isert.h
index b9d6cc6917cf..dfe4a2ebef0d 100644
--- a/drivers/infiniband/ulp/isert/ib_isert.h
+++ b/drivers/infiniband/ulp/isert/ib_isert.h
@@ -131,7 +131,7 @@ struct isert_device {
};
struct isert_np {
- wait_queue_head_t np_accept_wq;
+ struct semaphore np_sem;
struct rdma_cm_id *np_cm_id;
struct mutex np_accept_mutex;
struct list_head np_accept_list;