diff options
Diffstat (limited to 'drivers/scsi/xen-scsifront.c')
| -rw-r--r-- | drivers/scsi/xen-scsifront.c | 1026 |
1 files changed, 1026 insertions, 0 deletions
diff --git a/drivers/scsi/xen-scsifront.c b/drivers/scsi/xen-scsifront.c new file mode 100644 index 000000000000..34199d206ba6 --- /dev/null +++ b/drivers/scsi/xen-scsifront.c @@ -0,0 +1,1026 @@ +/* + * Xen SCSI frontend driver + * + * Copyright (c) 2008, FUJITSU Limited + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License version 2 + * as published by the Free Software Foundation; or, when distributed + * separately from the Linux kernel or incorporated into other + * software packages, subject to the following license: + * + * Permission is hereby granted, free of charge, to any person obtaining a copy + * of this source file (the "Software"), to deal in the Software without + * restriction, including without limitation the rights to use, copy, modify, + * merge, publish, distribute, sublicense, and/or sell copies of the Software, + * and to permit persons to whom the Software is furnished to do so, subject to + * the following conditions: + * + * The above copyright notice and this permission notice shall be included in + * all copies or substantial portions of the Software. + * + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE + * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING + * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS + * IN THE SOFTWARE. + */ + +#include <linux/module.h> +#include <linux/kernel.h> +#include <linux/device.h> +#include <linux/wait.h> +#include <linux/interrupt.h> +#include <linux/mutex.h> +#include <linux/spinlock.h> +#include <linux/sched.h> +#include <linux/blkdev.h> +#include <linux/pfn.h> +#include <linux/slab.h> +#include <linux/bitops.h> + +#include <scsi/scsi_cmnd.h> +#include <scsi/scsi_device.h> +#include <scsi/scsi.h> +#include <scsi/scsi_host.h> + +#include <xen/xen.h> +#include <xen/xenbus.h> +#include <xen/grant_table.h> +#include <xen/events.h> +#include <xen/page.h> + +#include <xen/interface/grant_table.h> +#include <xen/interface/io/vscsiif.h> +#include <xen/interface/io/protocols.h> + +#include <asm/xen/hypervisor.h> + + +#define GRANT_INVALID_REF 0 + +#define VSCSIFRONT_OP_ADD_LUN 1 +#define VSCSIFRONT_OP_DEL_LUN 2 + +/* Tuning point. */ +#define VSCSIIF_DEFAULT_CMD_PER_LUN 10 +#define VSCSIIF_MAX_TARGET 64 +#define VSCSIIF_MAX_LUN 255 + +#define VSCSIIF_RING_SIZE __CONST_RING_SIZE(vscsiif, PAGE_SIZE) +#define VSCSIIF_MAX_REQS VSCSIIF_RING_SIZE + +#define vscsiif_grants_sg(_sg) (PFN_UP((_sg) * \ + sizeof(struct scsiif_request_segment))) + +struct vscsifrnt_shadow { + /* command between backend and frontend */ + unsigned char act; + uint16_t rqid; + + unsigned int nr_grants; /* number of grants in gref[] */ + struct scsiif_request_segment *sg; /* scatter/gather elements */ + + /* Do reset or abort function. */ + wait_queue_head_t wq_reset; /* reset work queue */ + int wait_reset; /* reset work queue condition */ + int32_t rslt_reset; /* reset response status: */ + /* SUCCESS or FAILED or: */ +#define RSLT_RESET_WAITING 0 +#define RSLT_RESET_ERR -1 + + /* Requested struct scsi_cmnd is stored from kernel. */ + struct scsi_cmnd *sc; + int gref[vscsiif_grants_sg(SG_ALL) + SG_ALL]; +}; + +struct vscsifrnt_info { + struct xenbus_device *dev; + + struct Scsi_Host *host; + int host_active; + + unsigned int evtchn; + unsigned int irq; + + grant_ref_t ring_ref; + struct vscsiif_front_ring ring; + struct vscsiif_response ring_rsp; + + spinlock_t shadow_lock; + DECLARE_BITMAP(shadow_free_bitmap, VSCSIIF_MAX_REQS); + struct vscsifrnt_shadow *shadow[VSCSIIF_MAX_REQS]; + + wait_queue_head_t wq_sync; + unsigned int wait_ring_available:1; + + char dev_state_path[64]; + struct task_struct *curr; +}; + +static DEFINE_MUTEX(scsifront_mutex); + +static void scsifront_wake_up(struct vscsifrnt_info *info) +{ + info->wait_ring_available = 0; + wake_up(&info->wq_sync); +} + +static int scsifront_get_rqid(struct vscsifrnt_info *info) +{ + unsigned long flags; + int free; + + spin_lock_irqsave(&info->shadow_lock, flags); + + free = find_first_bit(info->shadow_free_bitmap, VSCSIIF_MAX_REQS); + __clear_bit(free, info->shadow_free_bitmap); + + spin_unlock_irqrestore(&info->shadow_lock, flags); + + return free; +} + +static int _scsifront_put_rqid(struct vscsifrnt_info *info, uint32_t id) +{ + int empty = bitmap_empty(info->shadow_free_bitmap, VSCSIIF_MAX_REQS); + + __set_bit(id, info->shadow_free_bitmap); + info->shadow[id] = NULL; + + return empty || info->wait_ring_available; +} + +static void scsifront_put_rqid(struct vscsifrnt_info *info, uint32_t id) +{ + unsigned long flags; + int kick; + + spin_lock_irqsave(&info->shadow_lock, flags); + kick = _scsifront_put_rqid(info, id); + spin_unlock_irqrestore(&info->shadow_lock, flags); + + if (kick) + scsifront_wake_up(info); +} + +static struct vscsiif_request *scsifront_pre_req(struct vscsifrnt_info *info) +{ + struct vscsiif_front_ring *ring = &(info->ring); + struct vscsiif_request *ring_req; + uint32_t id; + + id = scsifront_get_rqid(info); /* use id in response */ + if (id >= VSCSIIF_MAX_REQS) + return NULL; + + ring_req = RING_GET_REQUEST(&(info->ring), ring->req_prod_pvt); + + ring->req_prod_pvt++; + + ring_req->rqid = (uint16_t)id; + + return ring_req; +} + +static void scsifront_do_request(struct vscsifrnt_info *info) +{ + struct vscsiif_front_ring *ring = &(info->ring); + int notify; + + RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(ring, notify); + if (notify) + notify_remote_via_irq(info->irq); +} + +static void scsifront_gnttab_done(struct vscsifrnt_info *info, uint32_t id) +{ + struct vscsifrnt_shadow *s = info->shadow[id]; + int i; + + if (s->sc->sc_data_direction == DMA_NONE) + return; + + for (i = 0; i < s->nr_grants; i++) { + if (unlikely(gnttab_query_foreign_access(s->gref[i]) != 0)) { + shost_printk(KERN_ALERT, info->host, KBUILD_MODNAME + "grant still in use by backend\n"); + BUG(); + } + gnttab_end_foreign_access(s->gref[i], 0, 0UL); + } + + kfree(s->sg); +} + +static void scsifront_cdb_cmd_done(struct vscsifrnt_info *info, + struct vscsiif_response *ring_rsp) +{ + struct scsi_cmnd *sc; + uint32_t id; + uint8_t sense_len; + + id = ring_rsp->rqid; + sc = info->shadow[id]->sc; + + BUG_ON(sc == NULL); + + scsifront_gnttab_done(info, id); + scsifront_put_rqid(info, id); + + sc->result = ring_rsp->rslt; + scsi_set_resid(sc, ring_rsp->residual_len); + + sense_len = min_t(uint8_t, VSCSIIF_SENSE_BUFFERSIZE, + ring_rsp->sense_len); + + if (sense_len) + memcpy(sc->sense_buffer, ring_rsp->sense_buffer, sense_len); + + sc->scsi_done(sc); +} + +static void scsifront_sync_cmd_done(struct vscsifrnt_info *info, + struct vscsiif_response *ring_rsp) +{ + uint16_t id = ring_rsp->rqid; + unsigned long flags; + struct vscsifrnt_shadow *shadow = info->shadow[id]; + int kick; + + spin_lock_irqsave(&info->shadow_lock, flags); + shadow->wait_reset = 1; + switch (shadow->rslt_reset) { + case RSLT_RESET_WAITING: + shadow->rslt_reset = ring_rsp->rslt; + break; + case RSLT_RESET_ERR: + kick = _scsifront_put_rqid(info, id); + spin_unlock_irqrestore(&info->shadow_lock, flags); + kfree(shadow); + if (kick) + scsifront_wake_up(info); + return; + default: + shost_printk(KERN_ERR, info->host, KBUILD_MODNAME + "bad reset state %d, possibly leaking %u\n", + shadow->rslt_reset, id); + break; + } + spin_unlock_irqrestore(&info->shadow_lock, flags); + + wake_up(&shadow->wq_reset); +} + +static int scsifront_cmd_done(struct vscsifrnt_info *info) +{ + struct vscsiif_response *ring_rsp; + RING_IDX i, rp; + int more_to_do = 0; + unsigned long flags; + + spin_lock_irqsave(info->host->host_lock, flags); + + rp = info->ring.sring->rsp_prod; + rmb(); /* ordering required respective to dom0 */ + for (i = info->ring.rsp_cons; i != rp; i++) { + + ring_rsp = RING_GET_RESPONSE(&info->ring, i); + + if (WARN(ring_rsp->rqid >= VSCSIIF_MAX_REQS || + test_bit(ring_rsp->rqid, info->shadow_free_bitmap), + "illegal rqid %u returned by backend!\n", + ring_rsp->rqid)) + continue; + + if (info->shadow[ring_rsp->rqid]->act == VSCSIIF_ACT_SCSI_CDB) + scsifront_cdb_cmd_done(info, ring_rsp); + else + scsifront_sync_cmd_done(info, ring_rsp); + } + + info->ring.rsp_cons = i; + + if (i != info->ring.req_prod_pvt) + RING_FINAL_CHECK_FOR_RESPONSES(&info->ring, more_to_do); + else + info->ring.sring->rsp_event = i + 1; + + info->wait_ring_available = 0; + + spin_unlock_irqrestore(info->host->host_lock, flags); + + wake_up(&info->wq_sync); + + return more_to_do; +} + +static irqreturn_t scsifront_irq_fn(int irq, void *dev_id) +{ + struct vscsifrnt_info *info = dev_id; + + while (scsifront_cmd_done(info)) + /* Yield point for this unbounded loop. */ + cond_resched(); + + return IRQ_HANDLED; +} + +static int map_data_for_request(struct vscsifrnt_info *info, + struct scsi_cmnd *sc, + struct vscsiif_request *ring_req, + struct vscsifrnt_shadow *shadow) +{ + grant_ref_t gref_head; + struct page *page; + int err, ref, ref_cnt = 0; + int grant_ro = (sc->sc_data_direction == DMA_TO_DEVICE); + unsigned int i, off, len, bytes; + unsigned int data_len = scsi_bufflen(sc); + unsigned int data_grants = 0, seg_grants = 0; + struct scatterlist *sg; + unsigned long mfn; + struct scsiif_request_segment *seg; + + ring_req->nr_segments = 0; + if (sc->sc_data_direction == DMA_NONE || !data_len) + return 0; + + scsi_for_each_sg(sc, sg, scsi_sg_count(sc), i) + data_grants += PFN_UP(sg->offset + sg->length); + + if (data_grants > VSCSIIF_SG_TABLESIZE) { + if (data_grants > info->host->sg_tablesize) { + shost_printk(KERN_ERR, info->host, KBUILD_MODNAME + "Unable to map request_buffer for command!\n"); + return -E2BIG; + } + seg_grants = vscsiif_grants_sg(data_grants); + shadow->sg = kcalloc(data_grants, + sizeof(struct scsiif_request_segment), GFP_ATOMIC); + if (!shadow->sg) + return -ENOMEM; + } + seg = shadow->sg ? : ring_req->seg; + + err = gnttab_alloc_grant_references(seg_grants + data_grants, + &gref_head); + if (err) { + kfree(shadow->sg); + shost_printk(KERN_ERR, info->host, KBUILD_MODNAME + "gnttab_alloc_grant_references() error\n"); + return -ENOMEM; + } + + if (seg_grants) { + page = virt_to_page(seg); + off = (unsigned long)seg & ~PAGE_MASK; + len = sizeof(struct scsiif_request_segment) * data_grants; + while (len > 0) { + bytes = min_t(unsigned int, len, PAGE_SIZE - off); + + ref = gnttab_claim_grant_reference(&gref_head); + BUG_ON(ref == -ENOSPC); + + mfn = pfn_to_mfn(page_to_pfn(page)); + gnttab_grant_foreign_access_ref(ref, + info->dev->otherend_id, mfn, 1); + shadow->gref[ref_cnt] = ref; + ring_req->seg[ref_cnt].gref = ref; + ring_req->seg[ref_cnt].offset = (uint16_t)off; + ring_req->seg[ref_cnt].length = (uint16_t)bytes; + + page++; + len -= bytes; + off = 0; + ref_cnt++; + } + BUG_ON(seg_grants < ref_cnt); + seg_grants = ref_cnt; + } + + scsi_for_each_sg(sc, sg, scsi_sg_count(sc), i) { + page = sg_page(sg); + off = sg->offset; + len = sg->length; + + while (len > 0 && data_len > 0) { + /* + * sg sends a scatterlist that is larger than + * the data_len it wants transferred for certain + * IO sizes. + */ + bytes = min_t(unsigned int, len, PAGE_SIZE - off); + bytes = min(bytes, data_len); + + ref = gnttab_claim_grant_reference(&gref_head); + BUG_ON(ref == -ENOSPC); + + mfn = pfn_to_mfn(page_to_pfn(page)); + gnttab_grant_foreign_access_ref(ref, + info->dev->otherend_id, mfn, grant_ro); + + shadow->gref[ref_cnt] = ref; + seg->gref = ref; + seg->offset = (uint16_t)off; + seg->length = (uint16_t)bytes; + + page++; + seg++; + len -= bytes; + data_len -= bytes; + off = 0; + ref_cnt++; + } + } + + if (seg_grants) + ring_req->nr_segments = VSCSIIF_SG_GRANT | seg_grants; + else + ring_req->nr_segments = (uint8_t)ref_cnt; + shadow->nr_grants = ref_cnt; + + return 0; +} + +static struct vscsiif_request *scsifront_command2ring( + struct vscsifrnt_info *info, struct scsi_cmnd *sc, + struct vscsifrnt_shadow *shadow) +{ + struct vscsiif_request *ring_req; + + memset(shadow, 0, sizeof(*shadow)); + + ring_req = scsifront_pre_req(info); + if (!ring_req) + return NULL; + + info->shadow[ring_req->rqid] = shadow; + shadow->rqid = ring_req->rqid; + + ring_req->id = sc->device->id; + ring_req->lun = sc->device->lun; + ring_req->channel = sc->device->channel; + ring_req->cmd_len = sc->cmd_len; + + BUG_ON(sc->cmd_len > VSCSIIF_MAX_COMMAND_SIZE); + + memcpy(ring_req->cmnd, sc->cmnd, sc->cmd_len); + + ring_req->sc_data_direction = (uint8_t)sc->sc_data_direction; + ring_req->timeout_per_command = sc->request->timeout / HZ; + + return ring_req; +} + +static int scsifront_queuecommand(struct Scsi_Host *shost, + struct scsi_cmnd *sc) +{ + struct vscsifrnt_info *info = shost_priv(shost); + struct vscsiif_request *ring_req; + struct vscsifrnt_shadow *shadow = scsi_cmd_priv(sc); + unsigned long flags; + int err; + uint16_t rqid; + + spin_lock_irqsave(shost->host_lock, flags); + if (RING_FULL(&info->ring)) + goto busy; + + ring_req = scsifront_command2ring(info, sc, shadow); + if (!ring_req) + goto busy; + + sc->result = 0; + + rqid = ring_req->rqid; + ring_req->act = VSCSIIF_ACT_SCSI_CDB; + + shadow->sc = sc; + shadow->act = VSCSIIF_ACT_SCSI_CDB; + + err = map_data_for_request(info, sc, ring_req, shadow); + if (err < 0) { + pr_debug("%s: err %d\n", __func__, err); + scsifront_put_rqid(info, rqid); + spin_unlock_irqrestore(shost->host_lock, flags); + if (err == -ENOMEM) + return SCSI_MLQUEUE_HOST_BUSY; + sc->result = DID_ERROR << 16; + sc->scsi_done(sc); + return 0; + } + + scsifront_do_request(info); + spin_unlock_irqrestore(shost->host_lock, flags); + + return 0; + +busy: + spin_unlock_irqrestore(shost->host_lock, flags); + pr_debug("%s: busy\n", __func__); + return SCSI_MLQUEUE_HOST_BUSY; +} + +/* + * Any exception handling (reset or abort) must be forwarded to the backend. + * We have to wait until an answer is returned. This answer contains the + * result to be returned to the requestor. + */ +static int scsifront_action_handler(struct scsi_cmnd *sc, uint8_t act) +{ + struct Scsi_Host *host = sc->device->host; + struct vscsifrnt_info *info = shost_priv(host); + struct vscsifrnt_shadow *shadow, *s = scsi_cmd_priv(sc); + struct vscsiif_request *ring_req; + int err = 0; + + shadow = kmalloc(sizeof(*shadow), GFP_NOIO); + if (!shadow) + return FAILED; + + spin_lock_irq(host->host_lock); + + for (;;) { + if (!RING_FULL(&info->ring)) { + ring_req = scsifront_command2ring(info, sc, shadow); + if (ring_req) + break; + } + if (err) { + spin_unlock_irq(host->host_lock); + kfree(shadow); + return FAILED; + } + info->wait_ring_available = 1; + spin_unlock_irq(host->host_lock); + err = wait_event_interruptible(info->wq_sync, + !info->wait_ring_available); + spin_lock_irq(host->host_lock); + } + + ring_req->act = act; + ring_req->ref_rqid = s->rqid; + + shadow->act = act; + shadow->rslt_reset = RSLT_RESET_WAITING; + init_waitqueue_head(&shadow->wq_reset); + + ring_req->nr_segments = 0; + + scsifront_do_request(info); + + spin_unlock_irq(host->host_lock); + err = wait_event_interruptible(shadow->wq_reset, shadow->wait_reset); + spin_lock_irq(host->host_lock); + + if (!err) { + err = shadow->rslt_reset; + scsifront_put_rqid(info, shadow->rqid); + kfree(shadow); + } else { + spin_lock(&info->shadow_lock); + shadow->rslt_reset = RSLT_RESET_ERR; + spin_unlock(&info->shadow_lock); + err = FAILED; + } + + spin_unlock_irq(host->host_lock); + return err; +} + +static int scsifront_eh_abort_handler(struct scsi_cmnd *sc) +{ + pr_debug("%s\n", __func__); + return scsifront_action_handler(sc, VSCSIIF_ACT_SCSI_ABORT); +} + +static int scsifront_dev_reset_handler(struct scsi_cmnd *sc) +{ + pr_debug("%s\n", __func__); + return scsifront_action_handler(sc, VSCSIIF_ACT_SCSI_RESET); +} + +static int scsifront_sdev_configure(struct scsi_device *sdev) +{ + struct vscsifrnt_info *info = shost_priv(sdev->host); + + if (info && current == info->curr) + xenbus_printf(XBT_NIL, info->dev->nodename, + info->dev_state_path, "%d", XenbusStateConnected); + + return 0; +} + +static void scsifront_sdev_destroy(struct scsi_device *sdev) +{ + struct vscsifrnt_info *info = shost_priv(sdev->host); + + if (info && current == info->curr) + xenbus_printf(XBT_NIL, info->dev->nodename, + info->dev_state_path, "%d", XenbusStateClosed); +} + +static struct scsi_host_template scsifront_sht = { + .module = THIS_MODULE, + .name = "Xen SCSI frontend driver", + .queuecommand = scsifront_queuecommand, + .eh_abort_handler = scsifront_eh_abort_handler, + .eh_device_reset_handler = scsifront_dev_reset_handler, + .slave_configure = scsifront_sdev_configure, + .slave_destroy = scsifront_sdev_destroy, + .cmd_per_lun = VSCSIIF_DEFAULT_CMD_PER_LUN, + .can_queue = VSCSIIF_MAX_REQS, + .this_id = -1, + .cmd_size = sizeof(struct vscsifrnt_shadow), + .sg_tablesize = VSCSIIF_SG_TABLESIZE, + .use_clustering = DISABLE_CLUSTERING, + .proc_name = "scsifront", +}; + +static int scsifront_alloc_ring(struct vscsifrnt_info *info) +{ + struct xenbus_device *dev = info->dev; + struct vscsiif_sring *sring; + int err = -ENOMEM; + + /***** Frontend to Backend ring start *****/ + sring = (struct vscsiif_sring *)__get_free_page(GFP_KERNEL); + if (!sring) { + xenbus_dev_fatal(dev, err, + "fail to allocate shared ring (Front to Back)"); + return err; + } + SHARED_RING_INIT(sring); + FRONT_RING_INIT(&info->ring, sring, PAGE_SIZE); + + err = xenbus_grant_ring(dev, virt_to_mfn(sring)); + if (err < 0) { + free_page((unsigned long)sring); + xenbus_dev_fatal(dev, err, + "fail to grant shared ring (Front to Back)"); + return err; + } + info->ring_ref = err; + + err = xenbus_alloc_evtchn(dev, &info->evtchn); + if (err) { + xenbus_dev_fatal(dev, err, "xenbus_alloc_evtchn"); + goto free_gnttab; + } + + err = bind_evtchn_to_irq(info->evtchn); + if (err <= 0) { + xenbus_dev_fatal(dev, err, "bind_evtchn_to_irq"); + goto free_gnttab; + } + + info->irq = err; + + err = request_threaded_irq(info->irq, NULL, scsifront_irq_fn, + IRQF_ONESHOT, "scsifront", info); + if (err) { + xenbus_dev_fatal(dev, err, "request_threaded_irq"); + goto free_irq; + } + + return 0; + +/* free resource */ +free_irq: + unbind_from_irqhandler(info->irq, info); +free_gnttab: + gnttab_end_foreign_access(info->ring_ref, 0, + (unsigned long)info->ring.sring); + + return err; +} + +static int scsifront_init_ring(struct vscsifrnt_info *info) +{ + struct xenbus_device *dev = info->dev; + struct xenbus_transaction xbt; + int err; + + pr_debug("%s\n", __func__); + + err = scsifront_alloc_ring(info); + if (err) + return err; + pr_debug("%s: %u %u\n", __func__, info->ring_ref, info->evtchn); + +again: + err = xenbus_transaction_start(&xbt); + if (err) + xenbus_dev_fatal(dev, err, "starting transaction"); + + err = xenbus_printf(xbt, dev->nodename, "ring-ref", "%u", + info->ring_ref); + if (err) { + xenbus_dev_fatal(dev, err, "%s", "writing ring-ref"); + goto fail; + } + + err = xenbus_printf(xbt, dev->nodename, "event-channel", "%u", + info->evtchn); + + if (err) { + xenbus_dev_fatal(dev, err, "%s", "writing event-channel"); + goto fail; + } + + err = xenbus_transaction_end(xbt, 0); + if (err) { + if (err == -EAGAIN) + goto again; + xenbus_dev_fatal(dev, err, "completing transaction"); + goto free_sring; + } + + return 0; + +fail: + xenbus_transaction_end(xbt, 1); +free_sring: + unbind_from_irqhandler(info->irq, info); + gnttab_end_foreign_access(info->ring_ref, 0, + (unsigned long)info->ring.sring); + + return err; +} + + +static int scsifront_probe(struct xenbus_device *dev, + const struct xenbus_device_id *id) +{ + struct vscsifrnt_info *info; + struct Scsi_Host *host; + int err = -ENOMEM; + char name[TASK_COMM_LEN]; + + host = scsi_host_alloc(&scsifront_sht, sizeof(*info)); + if (!host) { + xenbus_dev_fatal(dev, err, "fail to allocate scsi host"); + return err; + } + info = (struct vscsifrnt_info *)host->hostdata; + + dev_set_drvdata(&dev->dev, info); + info->dev = dev; + + bitmap_fill(info->shadow_free_bitmap, VSCSIIF_MAX_REQS); + + err = scsifront_init_ring(info); + if (err) { + scsi_host_put(host); + return err; + } + + init_waitqueue_head(&info->wq_sync); + spin_lock_init(&info->shadow_lock); + + snprintf(name, TASK_COMM_LEN, "vscsiif.%d", host->host_no); + + host->max_id = VSCSIIF_MAX_TARGET; + host->max_channel = 0; + host->max_lun = VSCSIIF_MAX_LUN; + host->max_sectors = (host->sg_tablesize - 1) * PAGE_SIZE / 512; + host->max_cmd_len = VSCSIIF_MAX_COMMAND_SIZE; + + err = scsi_add_host(host, &dev->dev); + if (err) { + dev_err(&dev->dev, "fail to add scsi host %d\n", err); + goto free_sring; + } + info->host = host; + info->host_active = 1; + + xenbus_switch_state(dev, XenbusStateInitialised); + + return 0; + +free_sring: + unbind_from_irqhandler(info->irq, info); + gnttab_end_foreign_access(info->ring_ref, 0, + (unsigned long)info->ring.sring); + scsi_host_put(host); + return err; +} + +static int scsifront_remove(struct xenbus_device *dev) +{ + struct vscsifrnt_info *info = dev_get_drvdata(&dev->dev); + + pr_debug("%s: %s removed\n", __func__, dev->nodename); + + mutex_lock(&scsifront_mutex); + if (info->host_active) { + /* Scsi_host not yet removed */ + scsi_remove_host(info->host); + info->host_active = 0; + } + mutex_unlock(&scsifront_mutex); + + gnttab_end_foreign_access(info->ring_ref, 0, + (unsigned long)info->ring.sring); + unbind_from_irqhandler(info->irq, info); + + scsi_host_put(info->host); + + return 0; +} + +static void scsifront_disconnect(struct vscsifrnt_info *info) +{ + struct xenbus_device *dev = info->dev; + struct Scsi_Host *host = info->host; + + pr_debug("%s: %s disconnect\n", __func__, dev->nodename); + + /* + * When this function is executed, all devices of + * Frontend have been deleted. + * Therefore, it need not block I/O before remove_host. + */ + + mutex_lock(&scsifront_mutex); + if (info->host_active) { + scsi_remove_host(host); + info->host_active = 0; + } + mutex_unlock(&scsifront_mutex); + + xenbus_frontend_closed(dev); +} + +static void scsifront_do_lun_hotplug(struct vscsifrnt_info *info, int op) +{ + struct xenbus_device *dev = info->dev; + int i, err = 0; + char str[64]; + char **dir; + unsigned int dir_n = 0; + unsigned int device_state; + unsigned int hst, chn, tgt, lun; + struct scsi_device *sdev; + + dir = xenbus_directory(XBT_NIL, dev->otherend, "vscsi-devs", &dir_n); + if (IS_ERR(dir)) + return; + + /* mark current task as the one allowed to modify device states */ + BUG_ON(info->curr); + info->curr = current; + + for (i = 0; i < dir_n; i++) { + /* read status */ + snprintf(str, sizeof(str), "vscsi-devs/%s/state", dir[i]); + err = xenbus_scanf(XBT_NIL, dev->otherend, str, "%u", + &device_state); + if (XENBUS_EXIST_ERR(err)) + continue; + + /* virtual SCSI device */ + snprintf(str, sizeof(str), "vscsi-devs/%s/v-dev", dir[i]); + err = xenbus_scanf(XBT_NIL, dev->otherend, str, + "%u:%u:%u:%u", &hst, &chn, &tgt, &lun); + if (XENBUS_EXIST_ERR(err)) + continue; + + /* + * Front device state path, used in slave_configure called + * on successfull scsi_add_device, and in slave_destroy called + * on remove of a device. + */ + snprintf(info->dev_state_path, sizeof(info->dev_state_path), + "vscsi-devs/%s/state", dir[i]); + + switch (op) { + case VSCSIFRONT_OP_ADD_LUN: + if (device_state != XenbusStateInitialised) + break; + + if (scsi_add_device(info->host, chn, tgt, lun)) { + dev_err(&dev->dev, "scsi_add_device\n"); + xenbus_printf(XBT_NIL, dev->nodename, + info->dev_state_path, + "%d", XenbusStateClosed); + } + break; + case VSCSIFRONT_OP_DEL_LUN: + if (device_state != XenbusStateClosing) + break; + + sdev = scsi_device_lookup(info->host, chn, tgt, lun); + if (sdev) { + scsi_remove_device(sdev); + scsi_device_put(sdev); + } + break; + default: + break; + } + } + + info->curr = NULL; + + kfree(dir); +} + +static void scsifront_read_backend_params(struct xenbus_device *dev, + struct vscsifrnt_info *info) +{ + unsigned int sg_grant; + int ret; + struct Scsi_Host *host = info->host; + + ret = xenbus_scanf(XBT_NIL, dev->otherend, "feature-sg-grant", "%u", + &sg_grant); + if (ret == 1 && sg_grant) { + sg_grant = min_t(unsigned int, sg_grant, SG_ALL); + sg_grant = max_t(unsigned int, sg_grant, VSCSIIF_SG_TABLESIZE); + host->sg_tablesize = min_t(unsigned int, sg_grant, + VSCSIIF_SG_TABLESIZE * PAGE_SIZE / + sizeof(struct scsiif_request_segment)); + host->max_sectors = (host->sg_tablesize - 1) * PAGE_SIZE / 512; + } + dev_info(&dev->dev, "using up to %d SG entries\n", host->sg_tablesize); +} + +static void scsifront_backend_changed(struct xenbus_device *dev, + enum xenbus_state backend_state) +{ + struct vscsifrnt_info *info = dev_get_drvdata(&dev->dev); + + pr_debug("%s: %p %u %u\n", __func__, dev, dev->state, backend_state); + + switch (backend_state) { + case XenbusStateUnknown: + case XenbusStateInitialising: + case XenbusStateInitWait: + case XenbusStateInitialised: + break; + + case XenbusStateConnected: + scsifront_read_backend_params(dev, info); + if (xenbus_read_driver_state(dev->nodename) == + XenbusStateInitialised) + scsifront_do_lun_hotplug(info, VSCSIFRONT_OP_ADD_LUN); + + if (dev->state != XenbusStateConnected) + xenbus_switch_state(dev, XenbusStateConnected); + break; + + case XenbusStateClosed: + if (dev->state == XenbusStateClosed) + break; + /* Missed the backend's Closing state -- fallthrough */ + case XenbusStateClosing: + scsifront_disconnect(info); + break; + + case XenbusStateReconfiguring: + scsifront_do_lun_hotplug(info, VSCSIFRONT_OP_DEL_LUN); + xenbus_switch_state(dev, XenbusStateReconfiguring); + break; + + case XenbusStateReconfigured: + scsifront_do_lun_hotplug(info, VSCSIFRONT_OP_ADD_LUN); + xenbus_switch_state(dev, XenbusStateConnected); + break; + } +} + +static const struct xenbus_device_id scsifront_ids[] = { + { "vscsi" }, + { "" } +}; + +static struct xenbus_driver scsifront_driver = { + .ids = scsifront_ids, + .probe = scsifront_probe, + .remove = scsifront_remove, + .otherend_changed = scsifront_backend_changed, +}; + +static int __init scsifront_init(void) +{ + if (!xen_domain()) + return -ENODEV; + + return xenbus_register_frontend(&scsifront_driver); +} +module_init(scsifront_init); + +static void __exit scsifront_exit(void) +{ + xenbus_unregister_driver(&scsifront_driver); +} +module_exit(scsifront_exit); + +MODULE_DESCRIPTION("Xen SCSI frontend driver"); +MODULE_LICENSE("GPL"); +MODULE_ALIAS("xen:vscsi"); +MODULE_AUTHOR("Juergen Gross <jgross@suse.com>"); 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