[SCSI] iscsi: fix writepsace race

We can race and misset the suspend bit if iscsi_write_space is
called then iscsi_send returns with a failure indicating
there is no space.

To handle this this patch returns a error upwards allowing xmitworker
to decide if we need to try and transmit again. For the no
write space case xmitworker will not retry, and instead
let iscsi_write_space queue it back up if needed (this relies
on the work queue code to properly requeue us if needed).

Signed-off-by: Mike Christie <michaelc@cs.wisc.edu>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>

diff --git a/drivers/scsi/iscsi_tcp.c b/drivers/scsi/iscsi_tcp.c
index 2abda80..7fa8593 100644 (file)
--- a/drivers/scsi/iscsi_tcp.c
+++ b/drivers/scsi/iscsi_tcp.c
@@ -1006,7 +1006,6 @@ iscsi_write_space(struct sock *sk)
 
        tcp_conn->old_write_space(sk);
        debug_tcp("iscsi_write_space: cid %d\n", conn->id);
-       clear_bit(ISCSI_SUSPEND_BIT, &conn->suspend_tx);
        scsi_queue_work(conn->session->host, &conn->xmitwork);
 }
 
@@ -1056,7 +1055,7 @@ iscsi_send(struct iscsi_conn *conn, struct iscsi_buf *buf, int size, int flags)
 {
        struct iscsi_tcp_conn *tcp_conn = conn->dd_data;
        struct socket *sk = tcp_conn->sock;
-       int offset = buf->sg.offset + buf->sent;
+       int offset = buf->sg.offset + buf->sent, res;
 
        /*
         * if we got use_sg=0 or are sending something we kmallocd
@@ -1067,10 +1066,22 @@ iscsi_send(struct iscsi_conn *conn, struct iscsi_buf *buf, int size, int flags)
         * slab case.
         */
        if (buf->use_sendmsg)
-               return sock_no_sendpage(sk, buf->sg.page, offset, size, flags);
+               res = sock_no_sendpage(sk, buf->sg.page, offset, size, flags);
        else
-               return tcp_conn->sendpage(sk, buf->sg.page, offset, size,
-                                         flags);
+               res = tcp_conn->sendpage(sk, buf->sg.page, offset, size, flags);
+
+       if (res >= 0) {
+               conn->txdata_octets += res;
+               buf->sent += res;
+               return res;
+       }
+
+       tcp_conn->sendpage_failures_cnt++;
+       if (res == -EAGAIN)
+               res = -ENOBUFS;
+       else
+               iscsi_conn_failure(conn, ISCSI_ERR_CONN_FAILED);
+       return res;
 }
 
 /**
@@ -1085,7 +1096,6 @@ iscsi_send(struct iscsi_conn *conn, struct iscsi_buf *buf, int size, int flags)
 static inline int
 iscsi_sendhdr(struct iscsi_conn *conn, struct iscsi_buf *buf, int datalen)
 {
-       struct iscsi_tcp_conn *tcp_conn;
        int flags = 0; /* MSG_DONTWAIT; */
        int res, size;
 
@@ -1097,17 +1107,10 @@ iscsi_sendhdr(struct iscsi_conn *conn, struct iscsi_buf *buf, int datalen)
        res = iscsi_send(conn, buf, size, flags);
        debug_tcp("sendhdr %d bytes, sent %d res %d\n", size, buf->sent, res);
        if (res >= 0) {
-               conn->txdata_octets += res;
-               buf->sent += res;
                if (size != res)
                        return -EAGAIN;
                return 0;
-       } else if (res == -EAGAIN) {
-               tcp_conn = conn->dd_data;
-               tcp_conn->sendpage_failures_cnt++;
-               set_bit(ISCSI_SUSPEND_BIT, &conn->suspend_tx);
-       } else if (res == -EPIPE)
-               iscsi_conn_failure(conn, ISCSI_ERR_CONN_FAILED);
+       }
 
        return res;
 }
@@ -1126,7 +1129,6 @@ static inline int
 iscsi_sendpage(struct iscsi_conn *conn, struct iscsi_buf *buf,
               int *count, int *sent)
 {
-       struct iscsi_tcp_conn *tcp_conn;
        int flags = 0; /* MSG_DONTWAIT; */
        int res, size;
 
@@ -1141,19 +1143,12 @@ iscsi_sendpage(struct iscsi_conn *conn, struct iscsi_buf *buf,
        debug_tcp("sendpage: %d bytes, sent %d left %d sent %d res %d\n",
                  size, buf->sent, *count, *sent, res);
        if (res >= 0) {
-               conn->txdata_octets += res;
-               buf->sent += res;
                *count -= res;
                *sent += res;
                if (size != res)
                        return -EAGAIN;
                return 0;
-       } else if (res == -EAGAIN) {
-               tcp_conn = conn->dd_data;
-               tcp_conn->sendpage_failures_cnt++;
-               set_bit(ISCSI_SUSPEND_BIT, &conn->suspend_tx);
-       } else if (res == -EPIPE)
-               iscsi_conn_failure(conn, ISCSI_ERR_CONN_FAILED);
+       }
 
        return res;
 }
@@ -1342,6 +1337,7 @@ static int
 iscsi_tcp_mtask_xmit(struct iscsi_conn *conn, struct iscsi_mgmt_task *mtask)
 {
        struct iscsi_tcp_mgmt_task *tcp_mtask = mtask->dd_data;
+       int rc;
 
        debug_scsi("mtask deq [cid %d state %x itt 0x%x]\n",
                conn->id, tcp_mtask->xmstate, mtask->itt);
@@ -1355,12 +1351,13 @@ iscsi_tcp_mtask_xmit(struct iscsi_conn *conn, struct iscsi_mgmt_task *mtask)
                    conn->hdrdgst_en)
                        iscsi_hdr_digest(conn, &tcp_mtask->headbuf,
                                        (u8*)tcp_mtask->hdrext);
-               if (iscsi_sendhdr(conn, &tcp_mtask->headbuf,
-                                 mtask->data_count)) {
+               rc = iscsi_sendhdr(conn, &tcp_mtask->headbuf,
+                                  mtask->data_count);
+               if (rc) {
                        tcp_mtask->xmstate |= XMSTATE_IMM_HDR;
                        if (mtask->data_count)
                                tcp_mtask->xmstate &= ~XMSTATE_IMM_DATA;
-                       return -EAGAIN;
+                       return rc;
                }
        }
 
@@ -1371,10 +1368,13 @@ iscsi_tcp_mtask_xmit(struct iscsi_conn *conn, struct iscsi_mgmt_task *mtask)
                 * Virtual buffer could be spreaded across multiple pages...
                 */
                do {
-                       if (iscsi_sendpage(conn, &tcp_mtask->sendbuf,
-                                  &mtask->data_count, &tcp_mtask->sent)) {
+                       int rc;
+
+                       rc = iscsi_sendpage(conn, &tcp_mtask->sendbuf,
+                                       &mtask->data_count, &tcp_mtask->sent);
+                       if (rc) {
                                tcp_mtask->xmstate |= XMSTATE_IMM_DATA;
-                               return -EAGAIN;
+                               return rc;
                        }
                } while (mtask->data_count);
        }
@@ -1396,16 +1396,19 @@ static inline int
 handle_xmstate_r_hdr(struct iscsi_conn *conn,
                     struct iscsi_tcp_cmd_task *tcp_ctask)
 {
+       int rc;
+
        tcp_ctask->xmstate &= ~XMSTATE_R_HDR;
        if (conn->hdrdgst_en)
                iscsi_hdr_digest(conn, &tcp_ctask->headbuf,
                                 (u8*)tcp_ctask->hdrext);
-       if (!iscsi_sendhdr(conn, &tcp_ctask->headbuf, 0)) {
+       rc = iscsi_sendhdr(conn, &tcp_ctask->headbuf, 0);
+       if (!rc) {
                BUG_ON(tcp_ctask->xmstate != XMSTATE_IDLE);
                return 0; /* wait for Data-In */
        }
        tcp_ctask->xmstate |= XMSTATE_R_HDR;
-       return -EAGAIN;
+       return rc;
 }
 
 static inline int
@@ -1413,16 +1416,16 @@ handle_xmstate_w_hdr(struct iscsi_conn *conn,
                     struct iscsi_cmd_task *ctask)
 {
        struct iscsi_tcp_cmd_task *tcp_ctask = ctask->dd_data;
+       int rc;
 
        tcp_ctask->xmstate &= ~XMSTATE_W_HDR;
        if (conn->hdrdgst_en)
                iscsi_hdr_digest(conn, &tcp_ctask->headbuf,
                                 (u8*)tcp_ctask->hdrext);
-       if (iscsi_sendhdr(conn, &tcp_ctask->headbuf, ctask->imm_count)) {
+       rc = iscsi_sendhdr(conn, &tcp_ctask->headbuf, ctask->imm_count);
+       if (rc)
                tcp_ctask->xmstate |= XMSTATE_W_HDR;
-               return -EAGAIN;
-       }
-       return 0;
+       return rc;
 }
 
 static inline int
@@ -1430,17 +1433,19 @@ handle_xmstate_data_digest(struct iscsi_conn *conn,
                           struct iscsi_cmd_task *ctask)
 {
        struct iscsi_tcp_cmd_task *tcp_ctask = ctask->dd_data;
+       int rc;
 
        tcp_ctask->xmstate &= ~XMSTATE_DATA_DIGEST;
        debug_tcp("resent data digest 0x%x\n", tcp_ctask->datadigest);
-       if (iscsi_digest_final_send(conn, ctask, &tcp_ctask->immbuf,
-                                   &tcp_ctask->datadigest, 0)) {
+       rc = iscsi_digest_final_send(conn, ctask, &tcp_ctask->immbuf,
+                                   &tcp_ctask->datadigest, 0);
+       if (rc) {
                tcp_ctask->xmstate |= XMSTATE_DATA_DIGEST;
                debug_tcp("resent data digest 0x%x fail!\n",
                          tcp_ctask->datadigest);
-               return -EAGAIN;
        }
-       return 0;
+
+       return rc;
 }
 
 static inline int
@@ -1448,6 +1453,7 @@ handle_xmstate_imm_data(struct iscsi_conn *conn, struct iscsi_cmd_task *ctask)
 {
        struct iscsi_tcp_cmd_task *tcp_ctask = ctask->dd_data;
        struct iscsi_tcp_conn *tcp_conn = conn->dd_data;
+       int rc;
 
        BUG_ON(!ctask->imm_count);
        tcp_ctask->xmstate &= ~XMSTATE_IMM_DATA;
@@ -1458,8 +1464,9 @@ handle_xmstate_imm_data(struct iscsi_conn *conn, struct iscsi_cmd_task *ctask)
        }
 
        for (;;) {
-               if (iscsi_sendpage(conn, &tcp_ctask->sendbuf, &ctask->imm_count,
-                                  &tcp_ctask->sent)) {
+               rc = iscsi_sendpage(conn, &tcp_ctask->sendbuf,
+                                  &ctask->imm_count, &tcp_ctask->sent);
+               if (rc) {
                        tcp_ctask->xmstate |= XMSTATE_IMM_DATA;
                        if (conn->datadgst_en) {
                                crypto_digest_final(tcp_conn->data_tx_tfm,
@@ -1467,7 +1474,7 @@ handle_xmstate_imm_data(struct iscsi_conn *conn, struct iscsi_cmd_task *ctask)
                                debug_tcp("tx imm sendpage fail 0x%x\n",
                                          tcp_ctask->datadigest);
                        }
-                       return -EAGAIN;
+                       return rc;
                }
                if (conn->datadgst_en)
                        crypto_digest_update(tcp_conn->data_tx_tfm,
@@ -1480,11 +1487,12 @@ handle_xmstate_imm_data(struct iscsi_conn *conn, struct iscsi_cmd_task *ctask)
        }
 
        if (conn->datadgst_en && !(tcp_ctask->xmstate & XMSTATE_W_PAD)) {
-               if (iscsi_digest_final_send(conn, ctask, &tcp_ctask->immbuf,
-                                           &tcp_ctask->immdigest, 1)) {
+               rc = iscsi_digest_final_send(conn, ctask, &tcp_ctask->immbuf,
+                                           &tcp_ctask->immdigest, 1);
+               if (rc) {
                        debug_tcp("sending imm digest 0x%x fail!\n",
                                  tcp_ctask->immdigest);
-                       return -EAGAIN;
+                       return rc;
                }
                debug_tcp("sending imm digest 0x%x\n", tcp_ctask->immdigest);
        }
@@ -1497,6 +1505,7 @@ handle_xmstate_uns_hdr(struct iscsi_conn *conn, struct iscsi_cmd_task *ctask)
 {
        struct iscsi_tcp_cmd_task *tcp_ctask = ctask->dd_data;
        struct iscsi_data_task *dtask;
+       int rc;
 
        tcp_ctask->xmstate |= XMSTATE_UNS_DATA;
        if (tcp_ctask->xmstate & XMSTATE_UNS_INIT) {
@@ -1507,10 +1516,12 @@ handle_xmstate_uns_hdr(struct iscsi_conn *conn, struct iscsi_cmd_task *ctask)
                                        (u8*)dtask->hdrext);
                tcp_ctask->xmstate &= ~XMSTATE_UNS_INIT;
        }
-       if (iscsi_sendhdr(conn, &tcp_ctask->headbuf, ctask->data_count)) {
+
+       rc = iscsi_sendhdr(conn, &tcp_ctask->headbuf, ctask->data_count);
+       if (rc) {
                tcp_ctask->xmstate &= ~XMSTATE_UNS_DATA;
                tcp_ctask->xmstate |= XMSTATE_UNS_HDR;
-               return -EAGAIN;
+               return rc;
        }
 
        debug_scsi("uns dout [itt 0x%x dlen %d sent %d]\n",
@@ -1524,6 +1535,7 @@ handle_xmstate_uns_data(struct iscsi_conn *conn, struct iscsi_cmd_task *ctask)
        struct iscsi_tcp_cmd_task *tcp_ctask = ctask->dd_data;
        struct iscsi_data_task *dtask = tcp_ctask->dtask;
        struct iscsi_tcp_conn *tcp_conn = conn->dd_data;
+       int rc;
 
        BUG_ON(!ctask->data_count);
        tcp_ctask->xmstate &= ~XMSTATE_UNS_DATA;
@@ -1536,8 +1548,9 @@ handle_xmstate_uns_data(struct iscsi_conn *conn, struct iscsi_cmd_task *ctask)
        for (;;) {
                int start = tcp_ctask->sent;
 
-               if (iscsi_sendpage(conn, &tcp_ctask->sendbuf,
-                                  &ctask->data_count, &tcp_ctask->sent)) {
+               rc = iscsi_sendpage(conn, &tcp_ctask->sendbuf,
+                                  &ctask->data_count, &tcp_ctask->sent);
+               if (rc) {
                        ctask->unsol_count -= tcp_ctask->sent - start;
                        tcp_ctask->xmstate |= XMSTATE_UNS_DATA;
                        /* will continue with this ctask later.. */
@@ -1547,7 +1560,7 @@ handle_xmstate_uns_data(struct iscsi_conn *conn, struct iscsi_cmd_task *ctask)
                                debug_tcp("tx uns data fail 0x%x\n",
                                          dtask->digest);
                        }
-                       return -EAGAIN;
+                       return rc;
                }
 
                BUG_ON(tcp_ctask->sent > ctask->total_length);
@@ -1574,12 +1587,13 @@ handle_xmstate_uns_data(struct iscsi_conn *conn, struct iscsi_cmd_task *ctask)
         */
        if (ctask->unsol_count) {
                if (conn->datadgst_en) {
-                       if (iscsi_digest_final_send(conn, ctask,
+                       rc = iscsi_digest_final_send(conn, ctask,
                                                    &dtask->digestbuf,
-                                                   &dtask->digest, 1)) {
+                                                   &dtask->digest, 1);
+                       if (rc) {
                                debug_tcp("send uns digest 0x%x fail\n",
                                          dtask->digest);
-                               return -EAGAIN;
+                               return rc;
                        }
                        debug_tcp("sending uns digest 0x%x, more uns\n",
                                  dtask->digest);
@@ -1589,12 +1603,13 @@ handle_xmstate_uns_data(struct iscsi_conn *conn, struct iscsi_cmd_task *ctask)
        }
 
        if (conn->datadgst_en && !(tcp_ctask->xmstate & XMSTATE_W_PAD)) {
-               if (iscsi_digest_final_send(conn, ctask,
+               rc = iscsi_digest_final_send(conn, ctask,
                                            &dtask->digestbuf,
-                                           &dtask->digest, 1)) {
+                                           &dtask->digest, 1);
+               if (rc) {
                        debug_tcp("send last uns digest 0x%x fail\n",
                                   dtask->digest);
-                       return -EAGAIN;
+                       return rc;
                }
                debug_tcp("sending uns digest 0x%x\n",dtask->digest);
        }
@@ -1610,7 +1625,7 @@ handle_xmstate_sol_data(struct iscsi_conn *conn, struct iscsi_cmd_task *ctask)
        struct iscsi_tcp_cmd_task *tcp_ctask = ctask->dd_data;
        struct iscsi_r2t_info *r2t = tcp_ctask->r2t;
        struct iscsi_data_task *dtask = &r2t->dtask;
-       int left;
+       int left, rc;
 
        tcp_ctask->xmstate &= ~XMSTATE_SOL_DATA;
        tcp_ctask->dtask = dtask;
@@ -1626,7 +1641,8 @@ solicit_again:
        if (!r2t->data_count)
                goto data_out_done;
 
-       if (iscsi_sendpage(conn, &r2t->sendbuf, &r2t->data_count, &r2t->sent)) {
+       rc = iscsi_sendpage(conn, &r2t->sendbuf, &r2t->data_count, &r2t->sent);
+       if (rc) {
                tcp_ctask->xmstate |= XMSTATE_SOL_DATA;
                /* will continue with this ctask later.. */
                if (conn->datadgst_en) {
@@ -1634,7 +1650,7 @@ solicit_again:
                                          (u8 *)&dtask->digest);
                        debug_tcp("r2t data send fail 0x%x\n", dtask->digest);
                }
-               return -EAGAIN;
+               return rc;
        }
 
        BUG_ON(r2t->data_count < 0);
@@ -1661,12 +1677,13 @@ data_out_done:
        left = r2t->data_length - r2t->sent;
        if (left) {
                if (conn->datadgst_en) {
-                       if (iscsi_digest_final_send(conn, ctask,
+                       rc = iscsi_digest_final_send(conn, ctask,
                                                    &dtask->digestbuf,
-                                                   &dtask->digest, 1)) {
+                                                   &dtask->digest, 1);
+                       if (rc) {
                                debug_tcp("send r2t data digest 0x%x"
                                          "fail\n", dtask->digest);
-                               return -EAGAIN;
+                               return rc;
                        }
                        debug_tcp("r2t data send digest 0x%x\n",
                                  dtask->digest);
@@ -1683,11 +1700,12 @@ data_out_done:
         */
        BUG_ON(tcp_ctask->r2t_data_count - r2t->data_length < 0);
        if (conn->datadgst_en) {
-               if (iscsi_digest_final_send(conn, ctask, &dtask->digestbuf,
-                                           &dtask->digest, 1)) {
+               rc = iscsi_digest_final_send(conn, ctask, &dtask->digestbuf,
+                                           &dtask->digest, 1);
+               if (rc) {
                        debug_tcp("send last r2t data digest 0x%x"
                                  "fail\n", dtask->digest);
-                       return -EAGAIN;
+                       return rc;
                }
                debug_tcp("r2t done dout digest 0x%x\n", dtask->digest);
        }
@@ -1713,15 +1731,16 @@ handle_xmstate_w_pad(struct iscsi_conn *conn, struct iscsi_cmd_task *ctask)
        struct iscsi_tcp_cmd_task *tcp_ctask = ctask->dd_data;
        struct iscsi_tcp_conn *tcp_conn = conn->dd_data;
        struct iscsi_data_task *dtask = tcp_ctask->dtask;
-       int sent;
+       int sent, rc;
 
        tcp_ctask->xmstate &= ~XMSTATE_W_PAD;
        iscsi_buf_init_iov(&tcp_ctask->sendbuf, (char*)&tcp_ctask->pad,
                            tcp_ctask->pad_count);
-       if (iscsi_sendpage(conn, &tcp_ctask->sendbuf, &tcp_ctask->pad_count,
-                          &sent)) {
+       rc = iscsi_sendpage(conn, &tcp_ctask->sendbuf, &tcp_ctask->pad_count,
+                          &sent);
+       if (rc) {
                tcp_ctask->xmstate |= XMSTATE_W_PAD;
-               return -EAGAIN;
+               return rc;
        }
 
        if (conn->datadgst_en) {
@@ -1729,22 +1748,24 @@ handle_xmstate_w_pad(struct iscsi_conn *conn, struct iscsi_cmd_task *ctask)
                                     &tcp_ctask->sendbuf.sg, 1);
                /* imm data? */
                if (!dtask) {
-                       if (iscsi_digest_final_send(conn, ctask,
+                       rc = iscsi_digest_final_send(conn, ctask,
                                                    &tcp_ctask->immbuf,
-                                                   &tcp_ctask->immdigest, 1)) {
+                                                   &tcp_ctask->immdigest, 1);
+                       if (rc) {
                                debug_tcp("send padding digest 0x%x"
                                          "fail!\n", tcp_ctask->immdigest);
-                               return -EAGAIN;
+                               return rc;
                        }
                        debug_tcp("done with padding, digest 0x%x\n",
                                  tcp_ctask->datadigest);
                } else {
-                       if (iscsi_digest_final_send(conn, ctask,
+                       rc = iscsi_digest_final_send(conn, ctask,
                                                    &dtask->digestbuf,
-                                                   &dtask->digest, 1)) {
+                                                   &dtask->digest, 1);
+                       if (rc) {
                                debug_tcp("send padding digest 0x%x"
                                          "fail\n", dtask->digest);
-                               return -EAGAIN;
+                               return rc;
                        }
                        debug_tcp("done with padding, digest 0x%x\n",
                                  dtask->digest);
@@ -1769,10 +1790,8 @@ iscsi_tcp_ctask_xmit(struct iscsi_conn *conn, struct iscsi_cmd_task *ctask)
        if (ctask->mtask)
                return rc;
 
-       if (tcp_ctask->xmstate & XMSTATE_R_HDR) {
-               rc = handle_xmstate_r_hdr(conn, tcp_ctask);
-               return rc;
-       }
+       if (tcp_ctask->xmstate & XMSTATE_R_HDR)
+               return handle_xmstate_r_hdr(conn, tcp_ctask);
 
        if (tcp_ctask->xmstate & XMSTATE_W_HDR) {
                rc = handle_xmstate_w_hdr(conn, ctask);
@@ -1824,10 +1843,11 @@ solicit_head_again:
                if (conn->hdrdgst_en)
                        iscsi_hdr_digest(conn, &r2t->headbuf,
                                        (u8*)r2t->dtask.hdrext);
-               if (iscsi_sendhdr(conn, &r2t->headbuf, r2t->data_count)) {
+               rc = iscsi_sendhdr(conn, &r2t->headbuf, r2t->data_count);
+               if (rc) {
                        tcp_ctask->xmstate &= ~XMSTATE_SOL_DATA;
                        tcp_ctask->xmstate |= XMSTATE_SOL_HDR;
-                       return -EAGAIN;
+                       return rc;
                }
 
                debug_scsi("sol dout [dsn %d itt 0x%x dlen %d sent %d]\n",

diff --git a/drivers/scsi/libiscsi.c b/drivers/scsi/libiscsi.c
index 256b87a..2673a11 100644 (file)
--- a/drivers/scsi/libiscsi.c
+++ b/drivers/scsi/libiscsi.c
@@ -513,10 +513,11 @@ EXPORT_SYMBOL_GPL(iscsi_conn_failure);
 static int iscsi_data_xmit(struct iscsi_conn *conn)
 {
        struct iscsi_transport *tt;
+       int rc = 0;
 
        if (unlikely(conn->suspend_tx)) {
                debug_scsi("conn %d Tx suspended!\n", conn->id);
-               return 0;
+               return -ENODATA;
        }
        tt = conn->session->tt;
 
@@ -536,13 +537,15 @@ static int iscsi_data_xmit(struct iscsi_conn *conn)
        BUG_ON(conn->ctask && conn->mtask);
 
        if (conn->ctask) {
-               if (tt->xmit_cmd_task(conn, conn->ctask))
+               rc = tt->xmit_cmd_task(conn, conn->ctask);
+               if (rc)
                        goto again;
                /* done with this in-progress ctask */
                conn->ctask = NULL;
        }
        if (conn->mtask) {
-               if (tt->xmit_mgmt_task(conn, conn->mtask))
+               rc = tt->xmit_mgmt_task(conn, conn->mtask);
+               if (rc)
                        goto again;
                /* done with this in-progress mtask */
                conn->mtask = NULL;
@@ -556,7 +559,8 @@ static int iscsi_data_xmit(struct iscsi_conn *conn)
                        list_add_tail(&conn->mtask->running,
                                      &conn->mgmt_run_list);
                        spin_unlock_bh(&conn->session->lock);
-                       if (tt->xmit_mgmt_task(conn, conn->mtask))
+                       rc = tt->xmit_mgmt_task(conn, conn->mtask);
+                       if (rc)
                                goto again;
                }
                /* done with this mtask */
@@ -574,7 +578,8 @@ static int iscsi_data_xmit(struct iscsi_conn *conn)
                if (list_empty(&conn->ctask->running))
                        list_add_tail(&conn->ctask->running, &conn->run_list);
                spin_unlock_bh(&conn->session->lock);
-               if (tt->xmit_cmd_task(conn, conn->ctask))
+               rc = tt->xmit_cmd_task(conn, conn->ctask);
+               if (rc)
                        goto again;
        }
        /* done with this ctask */
@@ -588,32 +593,34 @@ static int iscsi_data_xmit(struct iscsi_conn *conn)
                        list_add_tail(&conn->mtask->running,
                                      &conn->mgmt_run_list);
                        spin_unlock_bh(&conn->session->lock);
-                       if (tt->xmit_mgmt_task(conn, conn->mtask))
+                       rc = tt->xmit_mgmt_task(conn, conn->mtask);
+                       if (rc)
                                goto again;
                }
                /* done with this mtask */
                conn->mtask = NULL;
        }
 
-       return 0;
+       return -ENODATA;
 
 again:
        if (unlikely(conn->suspend_tx))
-               return 0;
+               return -ENODATA;
 
-       return -EAGAIN;
+       return rc;
 }
 
 static void iscsi_xmitworker(void *data)
 {
        struct iscsi_conn *conn = data;
-
+       int rc;
        /*
         * serialize Xmit worker on a per-connection basis.
         */
        mutex_lock(&conn->xmitmutex);
-       if (iscsi_data_xmit(conn))
-               scsi_queue_work(conn->session->host, &conn->xmitwork);
+       do {
+               rc = iscsi_data_xmit(conn);
+       } while (rc >= 0 || rc == -EAGAIN);
        mutex_unlock(&conn->xmitmutex);
 }
 

diff --git a/include/scsi/scsi_transport_iscsi.h b/include/scsi/scsi_transport_iscsi.h
index 92129b9..b684426 100644 (file)
--- a/include/scsi/scsi_transport_iscsi.h
+++ b/include/scsi/scsi_transport_iscsi.h
@@ -57,8 +57,12 @@ struct iscsi_mgmt_task;
  *                     Called from queuecommand with session lock held.
  * @init_mgmt_task:    Initialize a iscsi_mgmt_task and any internal structs.
  *                     Called from iscsi_conn_send_generic with xmitmutex.
- * @xmit_cmd_task:     requests LLD to transfer cmd task
- * @xmit_mgmt_task:    requests LLD to transfer mgmt task
+ * @xmit_cmd_task:     Requests LLD to transfer cmd task. Returns 0 or the
+ *                     the number of bytes transferred on success, and -Exyz
+ *                     value on error.
+ * @xmit_mgmt_task:    Requests LLD to transfer mgmt task. Returns 0 or the
+ *                     the number of bytes transferred on success, and -Exyz
+ *                     value on error.
  * @cleanup_cmd_task:  requests LLD to fail cmd task. Called with xmitmutex
  *                     and session->lock after the connection has been
  *                     suspended and terminated during recovery. If called