Khazhismel Kumykov writes:
>> >> + if (!list_empty(>conn_list_err))
>> > Does this check need to be under connlock?
>>
>> My understanding is that it is not necessary, since it is serialized
>> against the conn removal itself, through the rx_mutex, it seemed safe to
>> do the verification lockless.
>>
>> It can only race with the insertion, in which case, it will be safely
>> removed from the dispatch list here, under rx_mutex, and the worker will
>> detect and skipped it.
>
> My worry is the splice, which is under only connlock, not rx_mutex, which
> might lead to UB if we're checking empty while modifying the list_head ?
Hi,
Please consider the v4 below with the lock added.
-- >8 --
From: Bharath Ravi
Connection failure processing depends on a daemon being present to (at
least) stop the connection and start recovery. This is a problem on a
multipath scenario, where if the daemon failed for whatever reason, the
SCSI path is never marked as down, multipath won't perform the
failover and IO to the device will be forever waiting for that
connection to come back.
This patch performs the connection failure entirely inside the kernel.
This way, the failover can happen and pending IO can continue even if
the daemon is dead. Once the daemon comes alive again, it can execute
recovery procedures if applicable.
Changes since v3:
- Protect list_empty with connlock on session destroy
Changes since v2:
- Don't hold rx_mutex for too long at once
Changes since v1:
- Remove module parameter.
- Always do kernel-side stop work.
- Block recovery timeout handler if system is dying.
- send a CONN_TERM stop if the system is dying.
Cc: Mike Christie
Cc: Lee Duncan
Cc: Bart Van Assche
Reviewed-by: Lee Duncan
Co-developed-by: Dave Clausen
Signed-off-by: Dave Clausen
Co-developed-by: Nick Black
Signed-off-by: Nick Black
Co-developed-by: Vaibhav Nagarnaik
Signed-off-by: Vaibhav Nagarnaik
Co-developed-by: Anatol Pomazau
Signed-off-by: Anatol Pomazau
Co-developed-by: Tahsin Erdogan
Signed-off-by: Tahsin Erdogan
Co-developed-by: Frank Mayhar
Signed-off-by: Frank Mayhar
Co-developed-by: Junho Ryu
Signed-off-by: Junho Ryu
Co-developed-by: Khazhismel Kumykov
Signed-off-by: Khazhismel Kumykov
Signed-off-by: Bharath Ravi
Co-developed-by: Gabriel Krisman Bertazi
Signed-off-by: Gabriel Krisman Bertazi
---
drivers/scsi/scsi_transport_iscsi.c | 68 +
include/scsi/scsi_transport_iscsi.h | 1 +
2 files changed, 69 insertions(+)
diff --git a/drivers/scsi/scsi_transport_iscsi.c
b/drivers/scsi/scsi_transport_iscsi.c
index 271afea654e2..ba6cfaf71aef 100644
--- a/drivers/scsi/scsi_transport_iscsi.c
+++ b/drivers/scsi/scsi_transport_iscsi.c
@@ -86,6 +86,12 @@ struct iscsi_internal {
struct transport_container session_cont;
};
+/* Worker to perform connection failure on unresponsive connections
+ * completely in kernel space.
+ */
+static void stop_conn_work_fn(struct work_struct *work);
+static DECLARE_WORK(stop_conn_work, stop_conn_work_fn);
+
static atomic_t iscsi_session_nr; /* sysfs session id for next new session */
static struct workqueue_struct *iscsi_eh_timer_workq;
@@ -1611,6 +1617,7 @@ static DEFINE_MUTEX(rx_queue_mutex);
static LIST_HEAD(sesslist);
static DEFINE_SPINLOCK(sesslock);
static LIST_HEAD(connlist);
+static LIST_HEAD(connlist_err);
static DEFINE_SPINLOCK(connlock);
static uint32_t iscsi_conn_get_sid(struct iscsi_cls_conn *conn)
@@ -2247,6 +2254,7 @@ iscsi_create_conn(struct iscsi_cls_session *session, int
dd_size, uint32_t cid)
mutex_init(>ep_mutex);
INIT_LIST_HEAD(>conn_list);
+ INIT_LIST_HEAD(>conn_list_err);
conn->transport = transport;
conn->cid = cid;
@@ -2293,6 +2301,7 @@ int iscsi_destroy_conn(struct iscsi_cls_conn *conn)
spin_lock_irqsave(, flags);
list_del(>conn_list);
+ list_del(>conn_list_err);
spin_unlock_irqrestore(, flags);
transport_unregister_device(>dev);
@@ -2407,6 +2416,51 @@ int iscsi_offload_mesg(struct Scsi_Host *shost,
}
EXPORT_SYMBOL_GPL(iscsi_offload_mesg);
+static void stop_conn_work_fn(struct work_struct *work)
+{
+ struct iscsi_cls_conn *conn, *tmp;
+ unsigned long flags;
+ LIST_HEAD(recovery_list);
+
+ spin_lock_irqsave(, flags);
+ if (list_empty(_err)) {
+ spin_unlock_irqrestore(, flags);
+ return;
+ }
+ list_splice_init(_err, _list);
+ spin_unlock_irqrestore(, flags);
+
+ list_for_each_entry_safe(conn, tmp, _list, conn_list_err) {
+ uint32_t sid = iscsi_conn_get_sid(conn);
+ struct iscsi_cls_session *session;
+
+ mutex_lock(_queue_mutex);
+
+ session = iscsi_session_lookup(sid);
+ if (session) {
+ if (system_state != SYSTEM_RUNNING) {
+ session->recovery_tmo = 0;
+
