IB/iser: Fix possible SQ overflow

Fix a regression was introduced in commit 6df5a128f0fd ("IB/iser:
Suppress scsi command send completions").

The sig_count was wrongly set to be static variable, thus it is
possible that we won't reach to (sig_count % ISER_SIGNAL_BATCH) == 0
condition (due to races) and the send queue will be overflowed.

Instead keep sig_count per connection. We don't need it to be atomic
as we are safe under the iscsi session frwd_lock taken by libiscsi on
the queuecommand path.

Fixes: 6df5a128f0fd ("IB/iser: Suppress scsi command send completions")
Signed-off-by: Max Gurtovoy <maxg@mellanox.com>
Signed-off-by: Sagi Grimberg <sagig@mellanox.com>
Signed-off-by: Or Gerlitz <ogerlitz@mellanox.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>

diff --git a/drivers/infiniband/ulp/iser/iscsi_iser.h b/drivers/infiniband/ulp/iser/iscsi_iser.h
index 44d64b7..8a5663d 100644 (file)
--- a/drivers/infiniband/ulp/iser/iscsi_iser.h
+++ b/drivers/infiniband/ulp/iser/iscsi_iser.h
@@ -437,6 +437,7 @@ struct fast_reg_descriptor {
  * @cma_id:              rdma_cm connection maneger handle
  * @qp:                  Connection Queue-pair
  * @post_recv_buf_count: post receive counter
+ * @sig_count:           send work request signal count
  * @rx_wr:               receive work request for batch posts
  * @device:              reference to iser device
  * @comp:                iser completion context
@@ -457,6 +458,7 @@ struct ib_conn {
        struct rdma_cm_id           *cma_id;
        struct ib_qp                *qp;
        int                          post_recv_buf_count;
+       u8                           sig_count;
        struct ib_recv_wr            rx_wr[ISER_MIN_POSTED_RX];
        struct iser_device          *device;
        struct iser_comp            *comp;

diff --git a/drivers/infiniband/ulp/iser/iser_initiator.c b/drivers/infiniband/ulp/iser/iser_initiator.c
index 5a489ea..3821633 100644 (file)
--- a/drivers/infiniband/ulp/iser/iser_initiator.c
+++ b/drivers/infiniband/ulp/iser/iser_initiator.c
@@ -369,7 +369,7 @@ static int iser_post_rx_bufs(struct iscsi_conn *conn, struct iscsi_hdr *req)
        return 0;
 }
 
-static inline bool iser_signal_comp(int sig_count)
+static inline bool iser_signal_comp(u8 sig_count)
 {
        return ((sig_count % ISER_SIGNAL_CMD_COUNT) == 0);
 }
@@ -388,7 +388,7 @@ int iser_send_command(struct iscsi_conn *conn,
        struct iscsi_scsi_req *hdr = (struct iscsi_scsi_req *)task->hdr;
        struct scsi_cmnd *sc  =  task->sc;
        struct iser_tx_desc *tx_desc = &iser_task->desc;
-       static unsigned sig_count;
+       u8 sig_count = ++iser_conn->ib_conn.sig_count;
 
        edtl = ntohl(hdr->data_length);
 
@@ -435,7 +435,7 @@ int iser_send_command(struct iscsi_conn *conn,
        iser_task->status = ISER_TASK_STATUS_STARTED;
 
        err = iser_post_send(&iser_conn->ib_conn, tx_desc,
-                            iser_signal_comp(++sig_count));
+                            iser_signal_comp(sig_count));
        if (!err)
                return 0;