cifs: smbd: Check and extend sender credits in interrupt context

When a RDMA packet is received and server is extending send credits, we should
check and unblock senders immediately in IRQ context. Doing it in a worker
queue causes unnecessary delay and doesn't save much CPU on the receive path.

Signed-off-by: Long Li <longli@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

diff --git a/fs/cifs/smbdirect.c b/fs/cifs/smbdirect.c
index a6ae29b..8da43a5 100644 (file)
--- a/fs/cifs/smbdirect.c
+++ b/fs/cifs/smbdirect.c
@@ -459,25 +459,6 @@ static void smbd_post_send_credits(struct work_struct *work)
        check_and_send_immediate(info);
 }
 
-static void smbd_recv_done_work(struct work_struct *work)
-{
-       struct smbd_connection *info =
-               container_of(work, struct smbd_connection, recv_done_work);
-
-       /*
-        * We may have new send credits granted from remote peer
-        * If any sender is blcoked on lack of credets, unblock it
-        */
-       if (atomic_read(&info->send_credits))
-               wake_up_interruptible(&info->wait_send_queue);
-
-       /*
-        * Check if we need to send something to remote peer to
-        * grant more credits or respond to KEEP_ALIVE packet
-        */
-       check_and_send_immediate(info);
-}
-
 /* Called from softirq, when recv is done */
 static void recv_done(struct ib_cq *cq, struct ib_wc *wc)
 {
@@ -546,8 +527,15 @@ static void recv_done(struct ib_cq *cq, struct ib_wc *wc)
                atomic_dec(&info->receive_credits);
                info->receive_credit_target =
                        le16_to_cpu(data_transfer->credits_requested);
-               atomic_add(le16_to_cpu(data_transfer->credits_granted),
-                       &info->send_credits);
+               if (le16_to_cpu(data_transfer->credits_granted)) {
+                       atomic_add(le16_to_cpu(data_transfer->credits_granted),
+                               &info->send_credits);
+                       /*
+                        * We have new send credits granted from remote peer
+                        * If any sender is waiting for credits, unblock it
+                        */
+                       wake_up_interruptible(&info->wait_send_queue);
+               }
 
                log_incoming(INFO, "data flags %d data_offset %d "
                        "data_length %d remaining_data_length %d\n",
@@ -563,7 +551,12 @@ static void recv_done(struct ib_cq *cq, struct ib_wc *wc)
                        info->keep_alive_requested = KEEP_ALIVE_PENDING;
                }
 
-               queue_work(info->workqueue, &info->recv_done_work);
+               /*
+                * Check if we need to send something to remote peer to
+                * grant more credits or respond to KEEP_ALIVE packet
+                */
+               check_and_send_immediate(info);
+
                return;
 
        default:
@@ -1762,7 +1755,6 @@ static struct smbd_connection *_smbd_get_connection(
        atomic_set(&info->send_payload_pending, 0);
 
        INIT_WORK(&info->disconnect_work, smbd_disconnect_rdma_work);
-       INIT_WORK(&info->recv_done_work, smbd_recv_done_work);
        INIT_WORK(&info->post_send_credits_work, smbd_post_send_credits);
        info->new_credits_offered = 0;
        spin_lock_init(&info->lock_new_credits_offered);

diff --git a/fs/cifs/smbdirect.h b/fs/cifs/smbdirect.h
index 6ff880a..8ede915 100644 (file)
--- a/fs/cifs/smbdirect.h
+++ b/fs/cifs/smbdirect.h
@@ -67,7 +67,6 @@ struct smbd_connection {
        bool negotiate_done;
 
        struct work_struct disconnect_work;
-       struct work_struct recv_done_work;
        struct work_struct post_send_credits_work;
 
        spinlock_t lock_new_credits_offered;