IB/srp: Fix tracking of pending requests during error handling

If a SCSI abort completes, or the command completes successfully, then
the driver must remove the command from its queue of pending
commands.  Similarly, if a device reset succeeds, then all commands
queued for the given device must be removed from the queue.

Signed-off-by: Roland Dreier <rolandd@cisco.com>

2 files changed, 115 insertions, 84 deletions

diff --git a/drivers/infiniband/ulp/srp/ib_srp.c b/drivers/infiniband/ulp/srp/ib_srp.c
index 5bb55742ada..c32ce4348e1 100644
--- a/drivers/infiniband/ulp/srp/ib_srp.c
+++ b/drivers/infiniband/ulp/srp/ib_srp.c
@@ -409,6 +409,34 @@ static int srp_connect_target(struct srp_target_port *target)
         }
 }
 
+static void srp_unmap_data(struct scsi_cmnd *scmnd,
+                           struct srp_target_port *target,
+                           struct srp_request *req)
+{
+        struct scatterlist *scat;
+        int nents;
+
+        if (!scmnd->request_buffer ||
+            (scmnd->sc_data_direction != DMA_TO_DEVICE &&
+             scmnd->sc_data_direction != DMA_FROM_DEVICE))
+                return;
+
+        /*
+         * This handling of non-SG commands can be killed when the
+         * SCSI midlayer no longer generates non-SG commands.
+         */
+        if (likely(scmnd->use_sg)) {
+                nents = scmnd->use_sg;
+                scat  = scmnd->request_buffer;
+        } else {
+                nents = 1;
+                scat  = &req->fake_sg;
+        }
+
+        dma_unmap_sg(target->srp_host->dev->dma_device, scat, nents,
+                     scmnd->sc_data_direction);
+}
+
 static int srp_reconnect_target(struct srp_target_port *target)
 {
         struct ib_cm_id *new_cm_id;
@@ -455,16 +483,16 @@ static int srp_reconnect_target(struct srp_target_port *target)
         list_for_each_entry(req, &target->req_queue, list) {
                 req->scmnd->result = DID_RESET << 16;
                 req->scmnd->scsi_done(req->scmnd);
+                srp_unmap_data(req->scmnd, target, req);
         }
 
         target->rx_head  = 0;
         target->tx_head  = 0;
         target->tx_tail  = 0;
-        target->req_head = 0;
-        for (i = 0; i < SRP_SQ_SIZE - 1; ++i)
-                target->req_ring[i].next = i + 1;
-        target->req_ring[SRP_SQ_SIZE - 1].next = -1;
+        INIT_LIST_HEAD(&target->free_reqs);
         INIT_LIST_HEAD(&target->req_queue);
+        for (i = 0; i < SRP_SQ_SIZE; ++i)
+                list_add_tail(&target->req_ring[i].list, &target->free_reqs);
 
         ret = srp_connect_target(target);
         if (ret)
@@ -589,40 +617,10 @@ static int srp_map_data(struct scsi_cmnd *scmnd, struct srp_target_port *target,
         return len;
 }
 
-static void srp_unmap_data(struct scsi_cmnd *scmnd,
-                           struct srp_target_port *target,
-                           struct srp_request *req)
-{
-        struct scatterlist *scat;
-        int nents;
-
-        if (!scmnd->request_buffer ||
-            (scmnd->sc_data_direction != DMA_TO_DEVICE &&
-             scmnd->sc_data_direction != DMA_FROM_DEVICE))
-                return;
-
-        /*
-         * This handling of non-SG commands can be killed when the
-         * SCSI midlayer no longer generates non-SG commands.
-         */
-        if (likely(scmnd->use_sg)) {
-                nents = scmnd->use_sg;
-                scat  = scmnd->request_buffer;
-        } else {
-                nents = 1;
-                scat  = &req->fake_sg;
-        }
-
-        dma_unmap_sg(target->srp_host->dev->dma_device, scat, nents,
-                     scmnd->sc_data_direction);
-}
-
-static void srp_remove_req(struct srp_target_port *target, struct srp_request *req,
-                           int index)
+static void srp_remove_req(struct srp_target_port *target, struct srp_request *req)
 {
-        list_del(&req->list);
-        req->next = target->req_head;
-        target->req_head = index;
+        srp_unmap_data(req->scmnd, target, req);
+        list_move_tail(&req->list, &target->free_reqs);
 }
 
 static void srp_process_rsp(struct srp_target_port *target, struct srp_rsp *rsp)
@@ -647,7 +645,7 @@ static void srp_process_rsp(struct srp_target_port *target, struct srp_rsp *rsp)
                         req->tsk_status = rsp->data[3];
                 complete(&req->done);
         } else {
-                scmnd         = req->scmnd;
+                scmnd = req->scmnd;
                 if (!scmnd)
                         printk(KERN_ERR "Null scmnd for RSP w/tag %016llx\n",
                                (unsigned long long) rsp->tag);
@@ -665,14 +663,11 @@ static void srp_process_rsp(struct srp_target_port *target, struct srp_rsp *rsp)
                 else if (rsp->flags & (SRP_RSP_FLAG_DIOVER | SRP_RSP_FLAG_DIUNDER))
                         scmnd->resid = be32_to_cpu(rsp->data_in_res_cnt);
 
-                srp_unmap_data(scmnd, target, req);
-
                 if (!req->tsk_mgmt) {
-                        req->scmnd = NULL;
                         scmnd->host_scribble = (void *) -1L;
                         scmnd->scsi_done(scmnd);
 
-                        srp_remove_req(target, req, rsp->tag & ~SRP_TAG_TSK_MGMT);
+                        srp_remove_req(target, req);
                 } else
                         req->cmd_done = 1;
         }
@@ -859,7 +854,6 @@ static int srp_queuecommand(struct scsi_cmnd *scmnd,
         struct srp_request *req;
         struct srp_iu *iu;
         struct srp_cmd *cmd;
-        long req_index;
         int len;
 
         if (target->state == SRP_TARGET_CONNECTING)
@@ -879,22 +873,20 @@ static int srp_queuecommand(struct scsi_cmnd *scmnd,
         dma_sync_single_for_cpu(target->srp_host->dev->dma_device, iu->dma,
                                 SRP_MAX_IU_LEN, DMA_TO_DEVICE);
 
-        req_index = target->req_head;
+        req = list_entry(target->free_reqs.next, struct srp_request, list);
 
         scmnd->scsi_done     = done;
         scmnd->result        = 0;
-        scmnd->host_scribble = (void *) req_index;
+        scmnd->host_scribble = (void *) (long) req->index;
 
         cmd = iu->buf;
         memset(cmd, 0, sizeof *cmd);
 
         cmd->opcode = SRP_CMD;
         cmd->lun    = cpu_to_be64((u64) scmnd->device->lun << 48);
-        cmd->tag    = req_index;
+        cmd->tag    = req->index;
         memcpy(cmd->cdb, scmnd->cmnd, scmnd->cmd_len);
 
-        req = &target->req_ring[req_index];
-
         req->scmnd    = scmnd;
         req->cmd      = iu;
         req->cmd_done = 0;
@@ -919,8 +911,7 @@ static int srp_queuecommand(struct scsi_cmnd *scmnd,
                 goto err_unmap;
         }
 
-        target->req_head = req->next;
-        list_add_tail(&req->list, &target->req_queue);
+        list_move_tail(&req->list, &target->req_queue);
 
         return 0;
 
@@ -1143,30 +1134,20 @@ static int srp_cm_handler(struct ib_cm_id *cm_id, struct ib_cm_event *event)
         return 0;
 }
 
-static int srp_send_tsk_mgmt(struct scsi_cmnd *scmnd, u8 func)
+static int srp_send_tsk_mgmt(struct srp_target_port *target,
+                             struct srp_request *req, u8 func)
 {
-        struct srp_target_port *target = host_to_target(scmnd->device->host);
-        struct srp_request *req;
         struct srp_iu *iu;
         struct srp_tsk_mgmt *tsk_mgmt;
-        int req_index;
-        int ret = FAILED;
 
         spin_lock_irq(target->scsi_host->host_lock);
 
         if (target->state == SRP_TARGET_DEAD ||
             target->state == SRP_TARGET_REMOVED) {
-                scmnd->result = DID_BAD_TARGET << 16;
+                req->scmnd->result = DID_BAD_TARGET << 16;
                 goto out;
         }
 
-        if (scmnd->host_scribble == (void *) -1L)
-                goto out;
-
-        req_index = (long) scmnd->host_scribble;
-        printk(KERN_ERR "Abort for req_index %d\n", req_index);
-
-        req = &target->req_ring[req_index];
         init_completion(&req->done);
 
         iu = __srp_get_tx_iu(target);
@@ -1177,10 +1158,10 @@ static int srp_send_tsk_mgmt(struct scsi_cmnd *scmnd, u8 func)
         memset(tsk_mgmt, 0, sizeof *tsk_mgmt);
 
         tsk_mgmt->opcode        = SRP_TSK_MGMT;
-        tsk_mgmt->lun           = cpu_to_be64((u64) scmnd->device->lun << 48);
-        tsk_mgmt->tag           = req_index | SRP_TAG_TSK_MGMT;
+        tsk_mgmt->lun           = cpu_to_be64((u64) req->scmnd->device->lun << 48);
+        tsk_mgmt->tag           = req->index | SRP_TAG_TSK_MGMT;
         tsk_mgmt->tsk_mgmt_func = func;
-        tsk_mgmt->task_tag      = req_index;
+        tsk_mgmt->task_tag      = req->index;
 
         if (__srp_post_send(target, iu, sizeof *tsk_mgmt))
                 goto out;
@@ -1188,37 +1169,85 @@ static int srp_send_tsk_mgmt(struct scsi_cmnd *scmnd, u8 func)
         req->tsk_mgmt = iu;
 
         spin_unlock_irq(target->scsi_host->host_lock);
+
         if (!wait_for_completion_timeout(&req->done,
                                          msecs_to_jiffies(SRP_ABORT_TIMEOUT_MS)))
-                return FAILED;
-        spin_lock_irq(target->scsi_host->host_lock);
+                return -1;
 
-        if (req->cmd_done) {
-                srp_remove_req(target, req, req_index);
-                scmnd->scsi_done(scmnd);
-        } else if (!req->tsk_status) {
-                srp_remove_req(target, req, req_index);
-                scmnd->result = DID_ABORT << 16;
-                ret = SUCCESS;
-        }
+        return 0;
 
 out:
         spin_unlock_irq(target->scsi_host->host_lock);
-        return ret;
+        return -1;
+}
+
+static int srp_find_req(struct srp_target_port *target,
+                        struct scsi_cmnd *scmnd,
+                        struct srp_request **req)
+{
+        if (scmnd->host_scribble == (void *) -1L)
+                return -1;
+
+        *req = &target->req_ring[(long) scmnd->host_scribble];
+
+        return 0;
 }
 
 static int srp_abort(struct scsi_cmnd *scmnd)
 {
+        struct srp_target_port *target = host_to_target(scmnd->device->host);
+        struct srp_request *req;
+        int ret = SUCCESS;
+
         printk(KERN_ERR "SRP abort called\n");
 
-        return srp_send_tsk_mgmt(scmnd, SRP_TSK_ABORT_TASK);
+        if (srp_find_req(target, scmnd, &req))
+                return FAILED;
+        if (srp_send_tsk_mgmt(target, req, SRP_TSK_ABORT_TASK))
+                return FAILED;
+
+        spin_lock_irq(target->scsi_host->host_lock);
+
+        if (req->cmd_done) {
+                srp_remove_req(target, req);
+                scmnd->scsi_done(scmnd);
+        } else if (!req->tsk_status) {
+                srp_remove_req(target, req);
+                scmnd->result = DID_ABORT << 16;
+        } else
+                ret = FAILED;
+
+        spin_unlock_irq(target->scsi_host->host_lock);
+
+        return ret;
 }
 
 static int srp_reset_device(struct scsi_cmnd *scmnd)
 {
+        struct srp_target_port *target = host_to_target(scmnd->device->host);
+        struct srp_request *req, *tmp;
+
         printk(KERN_ERR "SRP reset_device called\n");
 
-        return srp_send_tsk_mgmt(scmnd, SRP_TSK_LUN_RESET);
+        if (srp_find_req(target, scmnd, &req))
+                return FAILED;
+        if (srp_send_tsk_mgmt(target, req, SRP_TSK_LUN_RESET))
+                return FAILED;
+        if (req->tsk_status)
+                return FAILED;
+
+        spin_lock_irq(target->scsi_host->host_lock);
+
+        list_for_each_entry_safe(req, tmp, &target->req_queue, list)
+                if (req->scmnd->device == scmnd->device) {
+                        req->scmnd->result = DID_RESET << 16;
+                        scmnd->scsi_done(scmnd);
+                        srp_remove_req(target, req);
+                }
+
+        spin_unlock_irq(target->scsi_host->host_lock);
+
+        return SUCCESS;
 }
 
 static int srp_reset_host(struct scsi_cmnd *scmnd)
@@ -1518,10 +1547,12 @@ static ssize_t srp_create_target(struct class_device *class_dev,
 
         INIT_WORK(&target->work, srp_reconnect_work, target);
 
-        for (i = 0; i < SRP_SQ_SIZE - 1; ++i)
-                target->req_ring[i].next = i + 1;
-        target->req_ring[SRP_SQ_SIZE - 1].next = -1;
+        INIT_LIST_HEAD(&target->free_reqs);
         INIT_LIST_HEAD(&target->req_queue);
+        for (i = 0; i < SRP_SQ_SIZE; ++i) {
+                target->req_ring[i].index = i;
+                list_add_tail(&target->req_ring[i].list, &target->free_reqs);
+        }
 
         ret = srp_parse_options(buf, target);
         if (ret)
diff --git a/drivers/infiniband/ulp/srp/ib_srp.h b/drivers/infiniband/ulp/srp/ib_srp.h
index bd7f7c3115d..c5cd43aae86 100644
--- a/drivers/infiniband/ulp/srp/ib_srp.h
+++ b/drivers/infiniband/ulp/srp/ib_srp.h
@@ -101,7 +101,7 @@ struct srp_request {
          */
         struct scatterlist      fake_sg;
         struct completion       done;
-        short                   next;
+        short                   index;
         u8                      cmd_done;
         u8                      tsk_status;
 };
@@ -133,7 +133,7 @@ struct srp_target_port {
         unsigned                tx_tail;
         struct srp_iu          *tx_ring[SRP_SQ_SIZE + 1];
 
-        int                     req_head;
+        struct list_head        free_reqs;
         struct list_head        req_queue;
         struct srp_request      req_ring[SRP_SQ_SIZE];