From ba06d1e1d3350a38476ea6b7655ba7c047baad67 Mon Sep 17 00:00:00 2001 From: Wanlong Gao Date: Tue, 12 Mar 2013 15:34:40 +1030 Subject: virtio-scsi: use pr_err() instead of printk() Convert the virtio-scsi driver to use pr_err() instead of printk(). Signed-off-by: Wanlong Gao Acked-by: Paolo Bonzini Signed-off-by: Rusty Russell --- drivers/scsi/virtio_scsi.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) (limited to 'drivers/scsi') diff --git a/drivers/scsi/virtio_scsi.c b/drivers/scsi/virtio_scsi.c index 3449a1f8c65..0f5dd2804ae 100644 --- a/drivers/scsi/virtio_scsi.c +++ b/drivers/scsi/virtio_scsi.c @@ -13,6 +13,8 @@ * */ +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt + #include #include #include @@ -794,8 +796,7 @@ static int __init init(void) virtscsi_cmd_cache = KMEM_CACHE(virtio_scsi_cmd, 0); if (!virtscsi_cmd_cache) { - printk(KERN_ERR "kmem_cache_create() for " - "virtscsi_cmd_cache failed\n"); + pr_err("kmem_cache_create() for virtscsi_cmd_cache failed\n"); goto error; } @@ -804,8 +805,7 @@ static int __init init(void) mempool_create_slab_pool(VIRTIO_SCSI_MEMPOOL_SZ, virtscsi_cmd_cache); if (!virtscsi_cmd_pool) { - printk(KERN_ERR "mempool_create() for" - "virtscsi_cmd_pool failed\n"); + pr_err("mempool_create() for virtscsi_cmd_pool failed\n"); goto error; } ret = register_virtio_driver(&virtio_scsi_driver); -- cgit v1.2.3-18-g5258 From 682993b4e445bdfe9935d5e6e298565b7e11d7ee Mon Sep 17 00:00:00 2001 From: Wanlong Gao Date: Wed, 20 Mar 2013 15:44:28 +1030 Subject: virtio-scsi: use virtqueue_add_sgs for command buffers Using the new virtqueue_add_sgs function lets us simplify the queueing path. In particular, all data protected by the tgt_lock is just gone (multiqueue will find a new use for the lock). Signed-off-by: Wanlong Gao Acked-by: Paolo Bonzini Reviewed-by: Asias He Signed-off-by: Rusty Russell --- drivers/scsi/virtio_scsi.c | 100 +++++++++++++++++---------------------------- 1 file changed, 37 insertions(+), 63 deletions(-) (limited to 'drivers/scsi') diff --git a/drivers/scsi/virtio_scsi.c b/drivers/scsi/virtio_scsi.c index 0f5dd2804ae..77206d0eb6a 100644 --- a/drivers/scsi/virtio_scsi.c +++ b/drivers/scsi/virtio_scsi.c @@ -61,11 +61,8 @@ struct virtio_scsi_vq { /* Per-target queue state */ struct virtio_scsi_target_state { - /* Protects sg. Lock hierarchy is tgt_lock -> vq_lock. */ + /* Never held at the same time as vq_lock. */ spinlock_t tgt_lock; - - /* For sglist construction when adding commands to the virtqueue. */ - struct scatterlist sg[]; }; /* Driver instance state */ @@ -353,75 +350,61 @@ static void virtscsi_event_done(struct virtqueue *vq) spin_unlock_irqrestore(&vscsi->event_vq.vq_lock, flags); }; -static void virtscsi_map_sgl(struct scatterlist *sg, unsigned int *p_idx, - struct scsi_data_buffer *sdb) -{ - struct sg_table *table = &sdb->table; - struct scatterlist *sg_elem; - unsigned int idx = *p_idx; - int i; - - for_each_sg(table->sgl, sg_elem, table->nents, i) - sg[idx++] = *sg_elem; - - *p_idx = idx; -} - /** - * virtscsi_map_cmd - map a scsi_cmd to a virtqueue scatterlist - * @vscsi : virtio_scsi state + * virtscsi_add_cmd - add a virtio_scsi_cmd to a virtqueue + * @vq : the struct virtqueue we're talking about * @cmd : command structure - * @out_num : number of read-only elements - * @in_num : number of write-only elements * @req_size : size of the request buffer * @resp_size : size of the response buffer - * - * Called with tgt_lock held. + * @gfp : flags to use for memory allocations */ -static void virtscsi_map_cmd(struct virtio_scsi_target_state *tgt, - struct virtio_scsi_cmd *cmd, - unsigned *out_num, unsigned *in_num, - size_t req_size, size_t resp_size) +static int virtscsi_add_cmd(struct virtqueue *vq, + struct virtio_scsi_cmd *cmd, + size_t req_size, size_t resp_size, gfp_t gfp) { struct scsi_cmnd *sc = cmd->sc; - struct scatterlist *sg = tgt->sg; - unsigned int idx = 0; + struct scatterlist *sgs[4], req, resp; + struct sg_table *out, *in; + unsigned out_num = 0, in_num = 0; + + out = in = NULL; + + if (sc && sc->sc_data_direction != DMA_NONE) { + if (sc->sc_data_direction != DMA_FROM_DEVICE) + out = &scsi_out(sc)->table; + if (sc->sc_data_direction != DMA_TO_DEVICE) + in = &scsi_in(sc)->table; + } /* Request header. */ - sg_set_buf(&sg[idx++], &cmd->req, req_size); + sg_init_one(&req, &cmd->req, req_size); + sgs[out_num++] = &req; /* Data-out buffer. */ - if (sc && sc->sc_data_direction != DMA_FROM_DEVICE) - virtscsi_map_sgl(sg, &idx, scsi_out(sc)); - - *out_num = idx; + if (out) + sgs[out_num++] = out->sgl; /* Response header. */ - sg_set_buf(&sg[idx++], &cmd->resp, resp_size); + sg_init_one(&resp, &cmd->resp, resp_size); + sgs[out_num + in_num++] = &resp; /* Data-in buffer */ - if (sc && sc->sc_data_direction != DMA_TO_DEVICE) - virtscsi_map_sgl(sg, &idx, scsi_in(sc)); + if (in) + sgs[out_num + in_num++] = in->sgl; - *in_num = idx - *out_num; + return virtqueue_add_sgs(vq, sgs, out_num, in_num, cmd, gfp); } -static int virtscsi_kick_cmd(struct virtio_scsi_target_state *tgt, - struct virtio_scsi_vq *vq, +static int virtscsi_kick_cmd(struct virtio_scsi_vq *vq, struct virtio_scsi_cmd *cmd, size_t req_size, size_t resp_size, gfp_t gfp) { - unsigned int out_num, in_num; unsigned long flags; int err; bool needs_kick = false; - spin_lock_irqsave(&tgt->tgt_lock, flags); - virtscsi_map_cmd(tgt, cmd, &out_num, &in_num, req_size, resp_size); - - spin_lock(&vq->vq_lock); - err = virtqueue_add_buf(vq->vq, tgt->sg, out_num, in_num, cmd, gfp); - spin_unlock(&tgt->tgt_lock); + spin_lock_irqsave(&vq->vq_lock, flags); + err = virtscsi_add_cmd(vq->vq, cmd, req_size, resp_size, gfp); if (!err) needs_kick = virtqueue_kick_prepare(vq->vq); @@ -435,7 +418,6 @@ static int virtscsi_kick_cmd(struct virtio_scsi_target_state *tgt, static int virtscsi_queuecommand(struct Scsi_Host *sh, struct scsi_cmnd *sc) { struct virtio_scsi *vscsi = shost_priv(sh); - struct virtio_scsi_target_state *tgt = vscsi->tgt[sc->device->id]; struct virtio_scsi_cmd *cmd; int ret; @@ -469,7 +451,7 @@ static int virtscsi_queuecommand(struct Scsi_Host *sh, struct scsi_cmnd *sc) BUG_ON(sc->cmd_len > VIRTIO_SCSI_CDB_SIZE); memcpy(cmd->req.cmd.cdb, sc->cmnd, sc->cmd_len); - if (virtscsi_kick_cmd(tgt, &vscsi->req_vq, cmd, + if (virtscsi_kick_cmd(&vscsi->req_vq, cmd, sizeof cmd->req.cmd, sizeof cmd->resp.cmd, GFP_ATOMIC) == 0) ret = 0; @@ -483,11 +465,10 @@ out: static int virtscsi_tmf(struct virtio_scsi *vscsi, struct virtio_scsi_cmd *cmd) { DECLARE_COMPLETION_ONSTACK(comp); - struct virtio_scsi_target_state *tgt = vscsi->tgt[cmd->sc->device->id]; int ret = FAILED; cmd->comp = ∁ - if (virtscsi_kick_cmd(tgt, &vscsi->ctrl_vq, cmd, + if (virtscsi_kick_cmd(&vscsi->ctrl_vq, cmd, sizeof cmd->req.tmf, sizeof cmd->resp.tmf, GFP_NOIO) < 0) goto out; @@ -588,20 +569,16 @@ static void virtscsi_init_vq(struct virtio_scsi_vq *virtscsi_vq, } static struct virtio_scsi_target_state *virtscsi_alloc_tgt( - struct virtio_device *vdev, int sg_elems) + struct virtio_device *vdev) { struct virtio_scsi_target_state *tgt; gfp_t gfp_mask = GFP_KERNEL; - /* We need extra sg elements at head and tail. */ - tgt = kmalloc(sizeof(*tgt) + sizeof(tgt->sg[0]) * (sg_elems + 2), - gfp_mask); - + tgt = kmalloc(sizeof(*tgt), gfp_mask); if (!tgt) return NULL; spin_lock_init(&tgt->tgt_lock); - sg_init_table(tgt->sg, sg_elems + 2); return tgt; } @@ -635,7 +612,7 @@ static int virtscsi_init(struct virtio_device *vdev, { int err; struct virtqueue *vqs[3]; - u32 i, sg_elems; + u32 i; vq_callback_t *callbacks[] = { virtscsi_ctrl_done, @@ -663,11 +640,8 @@ static int virtscsi_init(struct virtio_device *vdev, if (virtio_has_feature(vdev, VIRTIO_SCSI_F_HOTPLUG)) virtscsi_kick_event_all(vscsi); - /* We need to know how many segments before we allocate. */ - sg_elems = virtscsi_config_get(vdev, seg_max) ?: 1; - for (i = 0; i < num_targets; i++) { - vscsi->tgt[i] = virtscsi_alloc_tgt(vdev, sg_elems); + vscsi->tgt[i] = virtscsi_alloc_tgt(vdev); if (!vscsi->tgt[i]) { err = -ENOMEM; goto out; -- cgit v1.2.3-18-g5258 From bf9582910b26525d4eeaa9840b07e7bf820f04fb Mon Sep 17 00:00:00 2001 From: Rusty Russell Date: Wed, 20 Mar 2013 15:44:28 +1030 Subject: virtio_scsi: use virtqueue_add_inbuf() for virtscsi_kick_event. It's a bit clearer, and add_buf is going away. Signed-off-by: Rusty Russell Reviewed-by: Asias He --- drivers/scsi/virtio_scsi.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'drivers/scsi') diff --git a/drivers/scsi/virtio_scsi.c b/drivers/scsi/virtio_scsi.c index 77206d0eb6a..b53ba9e18f4 100644 --- a/drivers/scsi/virtio_scsi.c +++ b/drivers/scsi/virtio_scsi.c @@ -222,8 +222,8 @@ static int virtscsi_kick_event(struct virtio_scsi *vscsi, spin_lock_irqsave(&vscsi->event_vq.vq_lock, flags); - err = virtqueue_add_buf(vscsi->event_vq.vq, &sg, 0, 1, event_node, - GFP_ATOMIC); + err = virtqueue_add_inbuf(vscsi->event_vq.vq, &sg, 1, event_node, + GFP_ATOMIC); if (!err) virtqueue_kick(vscsi->event_vq.vq); -- cgit v1.2.3-18-g5258 From 5c370194df9a97248ca69e05bfbd2d21b4886fe5 Mon Sep 17 00:00:00 2001 From: Wanlong Gao Date: Mon, 8 Apr 2013 23:01:16 +0930 Subject: virtio-scsi: redo allocation of target data virtio_scsi_target_state is now empty. We will find new uses for it in the next few patches, so this patch does not drop it completely. And as James suggested, we use entries target_alloc and target_destroy in the host template to allocate and destroy the virtio_scsi_target_state of each target, attach this struct to scsi_target->hostdata. Now we can get at it from the sdev with scsi_target(sdev)->hostdata. No messing around with fixed size arrays and bulk memory allocation and no need to pass in the maximum target size as a parameter because everything should now happen dynamically. Cc: James Bottomley Cc: linux-scsi@vger.kernel.org Signed-off-by: Paolo Bonzini Signed-off-by: Wanlong Gao Reviewed-by: Asias He Signed-off-by: Rusty Russell --- drivers/scsi/virtio_scsi.c | 71 ++++++++++++++++------------------------------ 1 file changed, 25 insertions(+), 46 deletions(-) (limited to 'drivers/scsi') diff --git a/drivers/scsi/virtio_scsi.c b/drivers/scsi/virtio_scsi.c index b53ba9e18f4..ffa03e8cb19 100644 --- a/drivers/scsi/virtio_scsi.c +++ b/drivers/scsi/virtio_scsi.c @@ -75,8 +75,6 @@ struct virtio_scsi { /* Get some buffers ready for event vq */ struct virtio_scsi_event_node event_list[VIRTIO_SCSI_EVENT_LEN]; - - struct virtio_scsi_target_state *tgt[]; }; static struct kmem_cache *virtscsi_cmd_cache; @@ -530,6 +528,25 @@ static int virtscsi_abort(struct scsi_cmnd *sc) return virtscsi_tmf(vscsi, cmd); } +static int virtscsi_target_alloc(struct scsi_target *starget) +{ + struct virtio_scsi_target_state *tgt = + kmalloc(sizeof(*tgt), GFP_KERNEL); + if (!tgt) + return -ENOMEM; + + spin_lock_init(&tgt->tgt_lock); + + starget->hostdata = tgt; + return 0; +} + +static void virtscsi_target_destroy(struct scsi_target *starget) +{ + struct virtio_scsi_target_state *tgt = starget->hostdata; + kfree(tgt); +} + static struct scsi_host_template virtscsi_host_template = { .module = THIS_MODULE, .name = "Virtio SCSI HBA", @@ -542,6 +559,8 @@ static struct scsi_host_template virtscsi_host_template = { .can_queue = 1024, .dma_boundary = UINT_MAX, .use_clustering = ENABLE_CLUSTERING, + .target_alloc = virtscsi_target_alloc, + .target_destroy = virtscsi_target_destroy, }; #define virtscsi_config_get(vdev, fld) \ @@ -568,20 +587,6 @@ static void virtscsi_init_vq(struct virtio_scsi_vq *virtscsi_vq, virtscsi_vq->vq = vq; } -static struct virtio_scsi_target_state *virtscsi_alloc_tgt( - struct virtio_device *vdev) -{ - struct virtio_scsi_target_state *tgt; - gfp_t gfp_mask = GFP_KERNEL; - - tgt = kmalloc(sizeof(*tgt), gfp_mask); - if (!tgt) - return NULL; - - spin_lock_init(&tgt->tgt_lock); - return tgt; -} - static void virtscsi_scan(struct virtio_device *vdev) { struct Scsi_Host *shost = (struct Scsi_Host *)vdev->priv; @@ -591,28 +596,17 @@ static void virtscsi_scan(struct virtio_device *vdev) static void virtscsi_remove_vqs(struct virtio_device *vdev) { - struct Scsi_Host *sh = virtio_scsi_host(vdev); - struct virtio_scsi *vscsi = shost_priv(sh); - u32 i, num_targets; - /* Stop all the virtqueues. */ vdev->config->reset(vdev); - num_targets = sh->max_id; - for (i = 0; i < num_targets; i++) { - kfree(vscsi->tgt[i]); - vscsi->tgt[i] = NULL; - } - vdev->config->del_vqs(vdev); } static int virtscsi_init(struct virtio_device *vdev, - struct virtio_scsi *vscsi, int num_targets) + struct virtio_scsi *vscsi) { int err; struct virtqueue *vqs[3]; - u32 i; vq_callback_t *callbacks[] = { virtscsi_ctrl_done, @@ -640,18 +634,6 @@ static int virtscsi_init(struct virtio_device *vdev, if (virtio_has_feature(vdev, VIRTIO_SCSI_F_HOTPLUG)) virtscsi_kick_event_all(vscsi); - for (i = 0; i < num_targets; i++) { - vscsi->tgt[i] = virtscsi_alloc_tgt(vdev); - if (!vscsi->tgt[i]) { - err = -ENOMEM; - goto out; - } - } - err = 0; - -out: - if (err) - virtscsi_remove_vqs(vdev); return err; } @@ -663,12 +645,9 @@ static int virtscsi_probe(struct virtio_device *vdev) u32 sg_elems, num_targets; u32 cmd_per_lun; - /* Allocate memory and link the structs together. */ num_targets = virtscsi_config_get(vdev, max_target) + 1; - shost = scsi_host_alloc(&virtscsi_host_template, - sizeof(*vscsi) - + num_targets * sizeof(struct virtio_scsi_target_state)); + shost = scsi_host_alloc(&virtscsi_host_template, sizeof(*vscsi)); if (!shost) return -ENOMEM; @@ -678,7 +657,7 @@ static int virtscsi_probe(struct virtio_device *vdev) vscsi->vdev = vdev; vdev->priv = shost; - err = virtscsi_init(vdev, vscsi, num_targets); + err = virtscsi_init(vdev, vscsi); if (err) goto virtscsi_init_failed; @@ -735,7 +714,7 @@ static int virtscsi_restore(struct virtio_device *vdev) struct Scsi_Host *sh = virtio_scsi_host(vdev); struct virtio_scsi *vscsi = shost_priv(sh); - return virtscsi_init(vdev, vscsi, sh->max_id); + return virtscsi_init(vdev, vscsi); } #endif -- cgit v1.2.3-18-g5258 From 7f82b3c9158f3ce8eb9eaf0320a359de9ab6392c Mon Sep 17 00:00:00 2001 From: Paolo Bonzini Date: Mon, 8 Apr 2013 23:01:38 +0930 Subject: virtio-scsi: pass struct virtio_scsi to virtqueue completion function This will be needed soon in order to retrieve the per-target struct. Cc: linux-scsi@vger.kernel.org Signed-off-by: Paolo Bonzini Signed-off-by: Wanlong Gao Reviewed-by: Asias He Signed-off-by: Rusty Russell --- drivers/scsi/virtio_scsi.c | 17 +++++++++-------- 1 file changed, 9 insertions(+), 8 deletions(-) (limited to 'drivers/scsi') diff --git a/drivers/scsi/virtio_scsi.c b/drivers/scsi/virtio_scsi.c index ffa03e8cb19..c23560c6a32 100644 --- a/drivers/scsi/virtio_scsi.c +++ b/drivers/scsi/virtio_scsi.c @@ -104,7 +104,7 @@ static void virtscsi_compute_resid(struct scsi_cmnd *sc, u32 resid) * * Called with vq_lock held. */ -static void virtscsi_complete_cmd(void *buf) +static void virtscsi_complete_cmd(struct virtio_scsi *vscsi, void *buf) { struct virtio_scsi_cmd *cmd = buf; struct scsi_cmnd *sc = cmd->sc; @@ -165,7 +165,8 @@ static void virtscsi_complete_cmd(void *buf) sc->scsi_done(sc); } -static void virtscsi_vq_done(struct virtqueue *vq, void (*fn)(void *buf)) +static void virtscsi_vq_done(struct virtio_scsi *vscsi, struct virtqueue *vq, + void (*fn)(struct virtio_scsi *vscsi, void *buf)) { void *buf; unsigned int len; @@ -173,7 +174,7 @@ static void virtscsi_vq_done(struct virtqueue *vq, void (*fn)(void *buf)) do { virtqueue_disable_cb(vq); while ((buf = virtqueue_get_buf(vq, &len)) != NULL) - fn(buf); + fn(vscsi, buf); } while (!virtqueue_enable_cb(vq)); } @@ -184,11 +185,11 @@ static void virtscsi_req_done(struct virtqueue *vq) unsigned long flags; spin_lock_irqsave(&vscsi->req_vq.vq_lock, flags); - virtscsi_vq_done(vq, virtscsi_complete_cmd); + virtscsi_vq_done(vscsi, vq, virtscsi_complete_cmd); spin_unlock_irqrestore(&vscsi->req_vq.vq_lock, flags); }; -static void virtscsi_complete_free(void *buf) +static void virtscsi_complete_free(struct virtio_scsi *vscsi, void *buf) { struct virtio_scsi_cmd *cmd = buf; @@ -205,7 +206,7 @@ static void virtscsi_ctrl_done(struct virtqueue *vq) unsigned long flags; spin_lock_irqsave(&vscsi->ctrl_vq.vq_lock, flags); - virtscsi_vq_done(vq, virtscsi_complete_free); + virtscsi_vq_done(vscsi, vq, virtscsi_complete_free); spin_unlock_irqrestore(&vscsi->ctrl_vq.vq_lock, flags); }; @@ -329,7 +330,7 @@ static void virtscsi_handle_event(struct work_struct *work) virtscsi_kick_event(vscsi, event_node); } -static void virtscsi_complete_event(void *buf) +static void virtscsi_complete_event(struct virtio_scsi *vscsi, void *buf) { struct virtio_scsi_event_node *event_node = buf; @@ -344,7 +345,7 @@ static void virtscsi_event_done(struct virtqueue *vq) unsigned long flags; spin_lock_irqsave(&vscsi->event_vq.vq_lock, flags); - virtscsi_vq_done(vq, virtscsi_complete_event); + virtscsi_vq_done(vscsi, vq, virtscsi_complete_event); spin_unlock_irqrestore(&vscsi->event_vq.vq_lock, flags); }; -- cgit v1.2.3-18-g5258 From 10f34f64d3a50912ae49c67c08c9162effdf546a Mon Sep 17 00:00:00 2001 From: Paolo Bonzini Date: Mon, 8 Apr 2013 23:02:07 +0930 Subject: virtio-scsi: push vq lock/unlock into virtscsi_vq_done Avoid duplicated code in all of the callers. Cc: linux-scsi@vger.kernel.org Signed-off-by: Paolo Bonzini Signed-off-by: Wanlong Gao Reviewed-by: Asias He Signed-off-by: Rusty Russell --- drivers/scsi/virtio_scsi.c | 22 +++++++++------------- 1 file changed, 9 insertions(+), 13 deletions(-) (limited to 'drivers/scsi') diff --git a/drivers/scsi/virtio_scsi.c b/drivers/scsi/virtio_scsi.c index c23560c6a32..dc2daec9a10 100644 --- a/drivers/scsi/virtio_scsi.c +++ b/drivers/scsi/virtio_scsi.c @@ -165,28 +165,30 @@ static void virtscsi_complete_cmd(struct virtio_scsi *vscsi, void *buf) sc->scsi_done(sc); } -static void virtscsi_vq_done(struct virtio_scsi *vscsi, struct virtqueue *vq, +static void virtscsi_vq_done(struct virtio_scsi *vscsi, + struct virtio_scsi_vq *virtscsi_vq, void (*fn)(struct virtio_scsi *vscsi, void *buf)) { void *buf; unsigned int len; + unsigned long flags; + struct virtqueue *vq = virtscsi_vq->vq; + spin_lock_irqsave(&virtscsi_vq->vq_lock, flags); do { virtqueue_disable_cb(vq); while ((buf = virtqueue_get_buf(vq, &len)) != NULL) fn(vscsi, buf); } while (!virtqueue_enable_cb(vq)); + spin_unlock_irqrestore(&virtscsi_vq->vq_lock, flags); } static void virtscsi_req_done(struct virtqueue *vq) { struct Scsi_Host *sh = virtio_scsi_host(vq->vdev); struct virtio_scsi *vscsi = shost_priv(sh); - unsigned long flags; - spin_lock_irqsave(&vscsi->req_vq.vq_lock, flags); - virtscsi_vq_done(vscsi, vq, virtscsi_complete_cmd); - spin_unlock_irqrestore(&vscsi->req_vq.vq_lock, flags); + virtscsi_vq_done(vscsi, &vscsi->req_vq, virtscsi_complete_cmd); }; static void virtscsi_complete_free(struct virtio_scsi *vscsi, void *buf) @@ -203,11 +205,8 @@ static void virtscsi_ctrl_done(struct virtqueue *vq) { struct Scsi_Host *sh = virtio_scsi_host(vq->vdev); struct virtio_scsi *vscsi = shost_priv(sh); - unsigned long flags; - spin_lock_irqsave(&vscsi->ctrl_vq.vq_lock, flags); - virtscsi_vq_done(vscsi, vq, virtscsi_complete_free); - spin_unlock_irqrestore(&vscsi->ctrl_vq.vq_lock, flags); + virtscsi_vq_done(vscsi, &vscsi->ctrl_vq, virtscsi_complete_free); }; static int virtscsi_kick_event(struct virtio_scsi *vscsi, @@ -342,11 +341,8 @@ static void virtscsi_event_done(struct virtqueue *vq) { struct Scsi_Host *sh = virtio_scsi_host(vq->vdev); struct virtio_scsi *vscsi = shost_priv(sh); - unsigned long flags; - spin_lock_irqsave(&vscsi->event_vq.vq_lock, flags); - virtscsi_vq_done(vscsi, vq, virtscsi_complete_event); - spin_unlock_irqrestore(&vscsi->event_vq.vq_lock, flags); + virtscsi_vq_done(vscsi, &vscsi->event_vq, virtscsi_complete_event); }; /** -- cgit v1.2.3-18-g5258 From 9141a4ca0d9551729573042660e9bce83a01e0af Mon Sep 17 00:00:00 2001 From: Paolo Bonzini Date: Mon, 8 Apr 2013 23:03:25 +0930 Subject: virtio-scsi: introduce multiqueue support This patch adds queue steering to virtio-scsi. When a target is sent multiple requests, we always drive them to the same queue so that FIFO processing order is kept. However, if a target was idle, we can choose a queue arbitrarily. In this case the queue is chosen according to the current VCPU, so the driver expects the number of request queues to be equal to the number of VCPUs. This makes it easy and fast to select the queue, and also lets the driver optimize the IRQ affinity for the virtqueues (each virtqueue's affinity is set to the CPU that "owns" the queue). The speedup comes from improving cache locality and giving CPU affinity to the virtqueues, which is why this scheme was selected. Assuming that the thread that is sending requests to the device is I/O-bound, it is likely to be sleeping at the time the ISR is executed, and thus executing the ISR on the same processor that sent the requests is cheap. However, the kernel will not execute the ISR on the "best" processor unless you explicitly set the affinity. This is because in practice you will have many such I/O-bound processes and thus many otherwise idle processors. Then the kernel will execute the ISR on a random processor, rather than the one that is sending requests to the device. The alternative to per-CPU virtqueues is per-target virtqueues. To achieve the same locality, we could dynamically choose the virtqueue's affinity based on the CPU of the last task that sent a request. This is less appealing because we do not set the affinity directly---we only provide a hint to the irqbalanced running in userspace. Dynamically changing the affinity only works if the userspace applies the hint fast enough. Cc: linux-scsi@vger.kernel.org Signed-off-by: Paolo Bonzini Signed-off-by: Wanlong Gao Reviewed-by: Asias He Tested-by: Venkatesh Srinivas Signed-off-by: Rusty Russell --- drivers/scsi/virtio_scsi.c | 282 ++++++++++++++++++++++++++++++++++++++++----- 1 file changed, 254 insertions(+), 28 deletions(-) (limited to 'drivers/scsi') diff --git a/drivers/scsi/virtio_scsi.c b/drivers/scsi/virtio_scsi.c index dc2daec9a10..8dcdef0783d 100644 --- a/drivers/scsi/virtio_scsi.c +++ b/drivers/scsi/virtio_scsi.c @@ -22,12 +22,14 @@ #include #include #include +#include #include #include #include #define VIRTIO_SCSI_MEMPOOL_SZ 64 #define VIRTIO_SCSI_EVENT_LEN 8 +#define VIRTIO_SCSI_VQ_BASE 2 /* Command queue element */ struct virtio_scsi_cmd { @@ -59,22 +61,58 @@ struct virtio_scsi_vq { struct virtqueue *vq; }; -/* Per-target queue state */ +/* + * Per-target queue state. + * + * This struct holds the data needed by the queue steering policy. When a + * target is sent multiple requests, we need to drive them to the same queue so + * that FIFO processing order is kept. However, if a target was idle, we can + * choose a queue arbitrarily. In this case the queue is chosen according to + * the current VCPU, so the driver expects the number of request queues to be + * equal to the number of VCPUs. This makes it easy and fast to select the + * queue, and also lets the driver optimize the IRQ affinity for the virtqueues + * (each virtqueue's affinity is set to the CPU that "owns" the queue). + * + * An interesting effect of this policy is that only writes to req_vq need to + * take the tgt_lock. Read can be done outside the lock because: + * + * - writes of req_vq only occur when atomic_inc_return(&tgt->reqs) returns 1. + * In that case, no other CPU is reading req_vq: even if they were in + * virtscsi_queuecommand_multi, they would be spinning on tgt_lock. + * + * - reads of req_vq only occur when the target is not idle (reqs != 0). + * A CPU that enters virtscsi_queuecommand_multi will not modify req_vq. + * + * Similarly, decrements of reqs are never concurrent with writes of req_vq. + * Thus they can happen outside the tgt_lock, provided of course we make reqs + * an atomic_t. + */ struct virtio_scsi_target_state { - /* Never held at the same time as vq_lock. */ + /* This spinlock never held at the same time as vq_lock. */ spinlock_t tgt_lock; + + /* Count of outstanding requests. */ + atomic_t reqs; + + /* Currently active virtqueue for requests sent to this target. */ + struct virtio_scsi_vq *req_vq; }; /* Driver instance state */ struct virtio_scsi { struct virtio_device *vdev; - struct virtio_scsi_vq ctrl_vq; - struct virtio_scsi_vq event_vq; - struct virtio_scsi_vq req_vq; - /* Get some buffers ready for event vq */ struct virtio_scsi_event_node event_list[VIRTIO_SCSI_EVENT_LEN]; + + u32 num_queues; + + /* If the affinity hint is set for virtqueues */ + bool affinity_hint_set; + + struct virtio_scsi_vq ctrl_vq; + struct virtio_scsi_vq event_vq; + struct virtio_scsi_vq req_vqs[]; }; static struct kmem_cache *virtscsi_cmd_cache; @@ -109,6 +147,8 @@ static void virtscsi_complete_cmd(struct virtio_scsi *vscsi, void *buf) struct virtio_scsi_cmd *cmd = buf; struct scsi_cmnd *sc = cmd->sc; struct virtio_scsi_cmd_resp *resp = &cmd->resp.cmd; + struct virtio_scsi_target_state *tgt = + scsi_target(sc->device)->hostdata; dev_dbg(&sc->device->sdev_gendev, "cmd %p response %u status %#02x sense_len %u\n", @@ -163,6 +203,8 @@ static void virtscsi_complete_cmd(struct virtio_scsi *vscsi, void *buf) mempool_free(cmd, virtscsi_cmd_pool); sc->scsi_done(sc); + + atomic_dec(&tgt->reqs); } static void virtscsi_vq_done(struct virtio_scsi *vscsi, @@ -187,8 +229,42 @@ static void virtscsi_req_done(struct virtqueue *vq) { struct Scsi_Host *sh = virtio_scsi_host(vq->vdev); struct virtio_scsi *vscsi = shost_priv(sh); + int index = vq->index - VIRTIO_SCSI_VQ_BASE; + struct virtio_scsi_vq *req_vq = &vscsi->req_vqs[index]; - virtscsi_vq_done(vscsi, &vscsi->req_vq, virtscsi_complete_cmd); + /* + * Read req_vq before decrementing the reqs field in + * virtscsi_complete_cmd. + * + * With barriers: + * + * CPU #0 virtscsi_queuecommand_multi (CPU #1) + * ------------------------------------------------------------ + * lock vq_lock + * read req_vq + * read reqs (reqs = 1) + * write reqs (reqs = 0) + * increment reqs (reqs = 1) + * write req_vq + * + * Possible reordering without barriers: + * + * CPU #0 virtscsi_queuecommand_multi (CPU #1) + * ------------------------------------------------------------ + * lock vq_lock + * read reqs (reqs = 1) + * write reqs (reqs = 0) + * increment reqs (reqs = 1) + * write req_vq + * read (wrong) req_vq + * + * We do not need a full smp_rmb, because req_vq is required to get + * to tgt->reqs: tgt is &vscsi->tgt[sc->device->id], where sc is stored + * in the virtqueue as the user token. + */ + smp_read_barrier_depends(); + + virtscsi_vq_done(vscsi, req_vq, virtscsi_complete_cmd); }; static void virtscsi_complete_free(struct virtio_scsi *vscsi, void *buf) @@ -251,7 +327,7 @@ static void virtscsi_cancel_event_work(struct virtio_scsi *vscsi) } static void virtscsi_handle_transport_reset(struct virtio_scsi *vscsi, - struct virtio_scsi_event *event) + struct virtio_scsi_event *event) { struct scsi_device *sdev; struct Scsi_Host *shost = virtio_scsi_host(vscsi->vdev); @@ -410,9 +486,10 @@ static int virtscsi_kick_cmd(struct virtio_scsi_vq *vq, return err; } -static int virtscsi_queuecommand(struct Scsi_Host *sh, struct scsi_cmnd *sc) +static int virtscsi_queuecommand(struct virtio_scsi *vscsi, + struct virtio_scsi_vq *req_vq, + struct scsi_cmnd *sc) { - struct virtio_scsi *vscsi = shost_priv(sh); struct virtio_scsi_cmd *cmd; int ret; @@ -446,7 +523,7 @@ static int virtscsi_queuecommand(struct Scsi_Host *sh, struct scsi_cmnd *sc) BUG_ON(sc->cmd_len > VIRTIO_SCSI_CDB_SIZE); memcpy(cmd->req.cmd.cdb, sc->cmnd, sc->cmd_len); - if (virtscsi_kick_cmd(&vscsi->req_vq, cmd, + if (virtscsi_kick_cmd(req_vq, cmd, sizeof cmd->req.cmd, sizeof cmd->resp.cmd, GFP_ATOMIC) == 0) ret = 0; @@ -457,6 +534,55 @@ out: return ret; } +static int virtscsi_queuecommand_single(struct Scsi_Host *sh, + struct scsi_cmnd *sc) +{ + struct virtio_scsi *vscsi = shost_priv(sh); + struct virtio_scsi_target_state *tgt = + scsi_target(sc->device)->hostdata; + + atomic_inc(&tgt->reqs); + return virtscsi_queuecommand(vscsi, &vscsi->req_vqs[0], sc); +} + +static struct virtio_scsi_vq *virtscsi_pick_vq(struct virtio_scsi *vscsi, + struct virtio_scsi_target_state *tgt) +{ + struct virtio_scsi_vq *vq; + unsigned long flags; + u32 queue_num; + + spin_lock_irqsave(&tgt->tgt_lock, flags); + + /* + * The memory barrier after atomic_inc_return matches + * the smp_read_barrier_depends() in virtscsi_req_done. + */ + if (atomic_inc_return(&tgt->reqs) > 1) + vq = ACCESS_ONCE(tgt->req_vq); + else { + queue_num = smp_processor_id(); + while (unlikely(queue_num >= vscsi->num_queues)) + queue_num -= vscsi->num_queues; + + tgt->req_vq = vq = &vscsi->req_vqs[queue_num]; + } + + spin_unlock_irqrestore(&tgt->tgt_lock, flags); + return vq; +} + +static int virtscsi_queuecommand_multi(struct Scsi_Host *sh, + struct scsi_cmnd *sc) +{ + struct virtio_scsi *vscsi = shost_priv(sh); + struct virtio_scsi_target_state *tgt = + scsi_target(sc->device)->hostdata; + struct virtio_scsi_vq *req_vq = virtscsi_pick_vq(vscsi, tgt); + + return virtscsi_queuecommand(vscsi, req_vq, sc); +} + static int virtscsi_tmf(struct virtio_scsi *vscsi, struct virtio_scsi_cmd *cmd) { DECLARE_COMPLETION_ONSTACK(comp); @@ -533,6 +659,8 @@ static int virtscsi_target_alloc(struct scsi_target *starget) return -ENOMEM; spin_lock_init(&tgt->tgt_lock); + atomic_set(&tgt->reqs, 0); + tgt->req_vq = NULL; starget->hostdata = tgt; return 0; @@ -544,12 +672,28 @@ static void virtscsi_target_destroy(struct scsi_target *starget) kfree(tgt); } -static struct scsi_host_template virtscsi_host_template = { +static struct scsi_host_template virtscsi_host_template_single = { .module = THIS_MODULE, .name = "Virtio SCSI HBA", .proc_name = "virtio_scsi", - .queuecommand = virtscsi_queuecommand, .this_id = -1, + .queuecommand = virtscsi_queuecommand_single, + .eh_abort_handler = virtscsi_abort, + .eh_device_reset_handler = virtscsi_device_reset, + + .can_queue = 1024, + .dma_boundary = UINT_MAX, + .use_clustering = ENABLE_CLUSTERING, + .target_alloc = virtscsi_target_alloc, + .target_destroy = virtscsi_target_destroy, +}; + +static struct scsi_host_template virtscsi_host_template_multi = { + .module = THIS_MODULE, + .name = "Virtio SCSI HBA", + .proc_name = "virtio_scsi", + .this_id = -1, + .queuecommand = virtscsi_queuecommand_multi, .eh_abort_handler = virtscsi_abort, .eh_device_reset_handler = virtscsi_device_reset, @@ -577,6 +721,47 @@ static struct scsi_host_template virtscsi_host_template = { &__val, sizeof(__val)); \ }) +static void __virtscsi_set_affinity(struct virtio_scsi *vscsi, bool affinity) +{ + int i; + int cpu; + + /* In multiqueue mode, when the number of cpu is equal + * to the number of request queues, we let the qeueues + * to be private to one cpu by setting the affinity hint + * to eliminate the contention. + */ + if ((vscsi->num_queues == 1 || + vscsi->num_queues != num_online_cpus()) && affinity) { + if (vscsi->affinity_hint_set) + affinity = false; + else + return; + } + + if (affinity) { + i = 0; + for_each_online_cpu(cpu) { + virtqueue_set_affinity(vscsi->req_vqs[i].vq, cpu); + i++; + } + + vscsi->affinity_hint_set = true; + } else { + for (i = 0; i < vscsi->num_queues - VIRTIO_SCSI_VQ_BASE; i++) + virtqueue_set_affinity(vscsi->req_vqs[i].vq, -1); + + vscsi->affinity_hint_set = false; + } +} + +static void virtscsi_set_affinity(struct virtio_scsi *vscsi, bool affinity) +{ + get_online_cpus(); + __virtscsi_set_affinity(vscsi, affinity); + put_online_cpus(); +} + static void virtscsi_init_vq(struct virtio_scsi_vq *virtscsi_vq, struct virtqueue *vq) { @@ -593,6 +778,11 @@ static void virtscsi_scan(struct virtio_device *vdev) static void virtscsi_remove_vqs(struct virtio_device *vdev) { + struct Scsi_Host *sh = virtio_scsi_host(vdev); + struct virtio_scsi *vscsi = shost_priv(sh); + + virtscsi_set_affinity(vscsi, false); + /* Stop all the virtqueues. */ vdev->config->reset(vdev); @@ -603,27 +793,43 @@ static int virtscsi_init(struct virtio_device *vdev, struct virtio_scsi *vscsi) { int err; - struct virtqueue *vqs[3]; + u32 i; + u32 num_vqs; + vq_callback_t **callbacks; + const char **names; + struct virtqueue **vqs; + + num_vqs = vscsi->num_queues + VIRTIO_SCSI_VQ_BASE; + vqs = kmalloc(num_vqs * sizeof(struct virtqueue *), GFP_KERNEL); + callbacks = kmalloc(num_vqs * sizeof(vq_callback_t *), GFP_KERNEL); + names = kmalloc(num_vqs * sizeof(char *), GFP_KERNEL); + + if (!callbacks || !vqs || !names) { + err = -ENOMEM; + goto out; + } - vq_callback_t *callbacks[] = { - virtscsi_ctrl_done, - virtscsi_event_done, - virtscsi_req_done - }; - const char *names[] = { - "control", - "event", - "request" - }; + callbacks[0] = virtscsi_ctrl_done; + callbacks[1] = virtscsi_event_done; + names[0] = "control"; + names[1] = "event"; + for (i = VIRTIO_SCSI_VQ_BASE; i < num_vqs; i++) { + callbacks[i] = virtscsi_req_done; + names[i] = "request"; + } /* Discover virtqueues and write information to configuration. */ - err = vdev->config->find_vqs(vdev, 3, vqs, callbacks, names); + err = vdev->config->find_vqs(vdev, num_vqs, vqs, callbacks, names); if (err) - return err; + goto out; virtscsi_init_vq(&vscsi->ctrl_vq, vqs[0]); virtscsi_init_vq(&vscsi->event_vq, vqs[1]); - virtscsi_init_vq(&vscsi->req_vq, vqs[2]); + for (i = VIRTIO_SCSI_VQ_BASE; i < num_vqs; i++) + virtscsi_init_vq(&vscsi->req_vqs[i - VIRTIO_SCSI_VQ_BASE], + vqs[i]); + + virtscsi_set_affinity(vscsi, true); virtscsi_config_set(vdev, cdb_size, VIRTIO_SCSI_CDB_SIZE); virtscsi_config_set(vdev, sense_size, VIRTIO_SCSI_SENSE_SIZE); @@ -631,6 +837,14 @@ static int virtscsi_init(struct virtio_device *vdev, if (virtio_has_feature(vdev, VIRTIO_SCSI_F_HOTPLUG)) virtscsi_kick_event_all(vscsi); + err = 0; + +out: + kfree(names); + kfree(callbacks); + kfree(vqs); + if (err) + virtscsi_remove_vqs(vdev); return err; } @@ -641,10 +855,21 @@ static int virtscsi_probe(struct virtio_device *vdev) int err; u32 sg_elems, num_targets; u32 cmd_per_lun; + u32 num_queues; + struct scsi_host_template *hostt; + + /* We need to know how many queues before we allocate. */ + num_queues = virtscsi_config_get(vdev, num_queues) ? : 1; num_targets = virtscsi_config_get(vdev, max_target) + 1; - shost = scsi_host_alloc(&virtscsi_host_template, sizeof(*vscsi)); + if (num_queues == 1) + hostt = &virtscsi_host_template_single; + else + hostt = &virtscsi_host_template_multi; + + shost = scsi_host_alloc(hostt, + sizeof(*vscsi) + sizeof(vscsi->req_vqs[0]) * num_queues); if (!shost) return -ENOMEM; @@ -652,6 +877,7 @@ static int virtscsi_probe(struct virtio_device *vdev) shost->sg_tablesize = sg_elems; vscsi = shost_priv(shost); vscsi->vdev = vdev; + vscsi->num_queues = num_queues; vdev->priv = shost; err = virtscsi_init(vdev, vscsi); -- cgit v1.2.3-18-g5258 From 285e71ea6f3583a85e27cb2b9a7d8c35d4c0d558 Mon Sep 17 00:00:00 2001 From: Wanlong Gao Date: Mon, 8 Apr 2013 23:05:49 +0930 Subject: virtio-scsi: reset virtqueue affinity when doing cpu hotplug Add hot cpu notifier to reset the request virtqueue affinity when doing cpu hotplug. Cc: linux-scsi@vger.kernel.org Signed-off-by: Paolo Bonzini Signed-off-by: Wanlong Gao Reviewed-by: Asias He Signed-off-by: Rusty Russell --- drivers/scsi/virtio_scsi.c | 29 +++++++++++++++++++++++++++++ 1 file changed, 29 insertions(+) (limited to 'drivers/scsi') diff --git a/drivers/scsi/virtio_scsi.c b/drivers/scsi/virtio_scsi.c index 8dcdef0783d..2168258fb2c 100644 --- a/drivers/scsi/virtio_scsi.c +++ b/drivers/scsi/virtio_scsi.c @@ -110,6 +110,9 @@ struct virtio_scsi { /* If the affinity hint is set for virtqueues */ bool affinity_hint_set; + /* CPU hotplug notifier */ + struct notifier_block nb; + struct virtio_scsi_vq ctrl_vq; struct virtio_scsi_vq event_vq; struct virtio_scsi_vq req_vqs[]; @@ -762,6 +765,23 @@ static void virtscsi_set_affinity(struct virtio_scsi *vscsi, bool affinity) put_online_cpus(); } +static int virtscsi_cpu_callback(struct notifier_block *nfb, + unsigned long action, void *hcpu) +{ + struct virtio_scsi *vscsi = container_of(nfb, struct virtio_scsi, nb); + switch(action) { + case CPU_ONLINE: + case CPU_ONLINE_FROZEN: + case CPU_DEAD: + case CPU_DEAD_FROZEN: + __virtscsi_set_affinity(vscsi, true); + break; + default: + break; + } + return NOTIFY_OK; +} + static void virtscsi_init_vq(struct virtio_scsi_vq *virtscsi_vq, struct virtqueue *vq) { @@ -884,6 +904,13 @@ static int virtscsi_probe(struct virtio_device *vdev) if (err) goto virtscsi_init_failed; + vscsi->nb.notifier_call = &virtscsi_cpu_callback; + err = register_hotcpu_notifier(&vscsi->nb); + if (err) { + pr_err("registering cpu notifier failed\n"); + goto scsi_add_host_failed; + } + cmd_per_lun = virtscsi_config_get(vdev, cmd_per_lun) ?: 1; shost->cmd_per_lun = min_t(u32, cmd_per_lun, shost->can_queue); shost->max_sectors = virtscsi_config_get(vdev, max_sectors) ?: 0xFFFF; @@ -921,6 +948,8 @@ static void virtscsi_remove(struct virtio_device *vdev) scsi_remove_host(shost); + unregister_hotcpu_notifier(&vscsi->nb); + virtscsi_remove_vqs(vdev); scsi_host_put(shost); } -- cgit v1.2.3-18-g5258