[PATCH 3/5] ibmvfc: define per-queue state/list locks

From: Tyrel Datwyler
Date: Fri Dec 18 2020 - 18:23:37 EST

Define per-queue locks for protecting queue state and event pool
sent/free lists. The evt list lock is initially redundant but it allows
the driver to be modified in the follow-up patches to relax the queue
locking around submissions and completions.

Signed-off-by: Tyrel Datwyler <tyreld@xxxxxxxxxxxxx>
Reviewed-by: Brian King <brking@xxxxxxxxxxxxxxxxxx>
---
drivers/scsi/ibmvscsi/ibmvfc.c | 93 +++++++++++++++++++++++++++-------
drivers/scsi/ibmvscsi/ibmvfc.h | 7 ++-
2 files changed, 80 insertions(+), 20 deletions(-)

diff --git a/drivers/scsi/ibmvscsi/ibmvfc.c b/drivers/scsi/ibmvscsi/ibmvfc.c
index 8de2a25b05ee..69a6401ca504 100644
--- a/drivers/scsi/ibmvscsi/ibmvfc.c
+++ b/drivers/scsi/ibmvscsi/ibmvfc.c
@@ -176,8 +176,9 @@ static void ibmvfc_trc_start(struct ibmvfc_event *evt)
struct ibmvfc_mad_common *mad = &evt->iu.mad_common;
struct ibmvfc_fcp_cmd_iu *iu = ibmvfc_get_fcp_iu(vhost, vfc_cmd);
struct ibmvfc_trace_entry *entry;
+ int index = atomic_inc_return(&vhost->trace_index) & IBMVFC_TRACE_INDEX_MASK;

- entry = &vhost->trace[vhost->trace_index++];
+ entry = &vhost->trace[index];
entry->evt = evt;
entry->time = jiffies;
entry->fmt = evt->crq.format;
@@ -211,8 +212,10 @@ static void ibmvfc_trc_end(struct ibmvfc_event *evt)
struct ibmvfc_mad_common *mad = &evt->xfer_iu->mad_common;
struct ibmvfc_fcp_cmd_iu *iu = ibmvfc_get_fcp_iu(vhost, vfc_cmd);
struct ibmvfc_fcp_rsp *rsp = ibmvfc_get_fcp_rsp(vhost, vfc_cmd);
- struct ibmvfc_trace_entry *entry = &vhost->trace[vhost->trace_index++];
+ struct ibmvfc_trace_entry *entry;
+ int index = atomic_inc_return(&vhost->trace_index) & IBMVFC_TRACE_INDEX_MASK;

+ entry = &vhost->trace[index];
entry->evt = evt;
entry->time = jiffies;
entry->fmt = evt->crq.format;
@@ -805,6 +808,7 @@ static int ibmvfc_reset_crq(struct ibmvfc_host *vhost)
} while (rc == H_BUSY || H_IS_LONG_BUSY(rc));

spin_lock_irqsave(vhost->host->host_lock, flags);
+ spin_lock(vhost->crq.q_lock);
vhost->state = IBMVFC_NO_CRQ;
vhost->logged_in = 0;

@@ -821,6 +825,7 @@ static int ibmvfc_reset_crq(struct ibmvfc_host *vhost)
dev_warn(vhost->dev, "Partner adapter not ready\n");
else if (rc != 0)
dev_warn(vhost->dev, "Couldn't register crq (rc=%d)\n", rc);
+ spin_unlock(vhost->crq.q_lock);
spin_unlock_irqrestore(vhost->host->host_lock, flags);

return rc;
@@ -853,10 +858,16 @@ static int ibmvfc_valid_event(struct ibmvfc_event_pool *pool,
static void ibmvfc_free_event(struct ibmvfc_event *evt)
{
struct ibmvfc_event_pool *pool = &evt->queue->evt_pool;
+ unsigned long flags;

BUG_ON(!ibmvfc_valid_event(pool, evt));
BUG_ON(atomic_inc_return(&evt->free) != 1);
+
+ spin_lock_irqsave(&evt->queue->l_lock, flags);
list_add_tail(&evt->queue_list, &evt->queue->free);
+ if (evt->eh_comp)
+ complete(evt->eh_comp);
+ spin_unlock_irqrestore(&evt->queue->l_lock, flags);
}

/**
@@ -875,12 +886,27 @@ static void ibmvfc_scsi_eh_done(struct ibmvfc_event *evt)
cmnd->scsi_done(cmnd);
}

- if (evt->eh_comp)
- complete(evt->eh_comp);
-
ibmvfc_free_event(evt);
}

+/**
+ * ibmvfc_complete_purge - Complete failed command list
+ * @purge_list: list head of failed commands
+ *
+ * This function runs completions on commands to fail as a result of a
+ * host reset or platform migration. Caller must hold host_lock.
+ **/
+static void ibmvfc_complete_purge(struct list_head *purge_list)
+{
+ struct ibmvfc_event *evt, *pos;
+
+ list_for_each_entry_safe(evt, pos, purge_list, queue_list) {
+ list_del(&evt->queue_list);
+ ibmvfc_trc_end(evt);
+ evt->done(evt);
+ }
+}
+
/**
* ibmvfc_fail_request - Fail request with specified error code
* @evt: ibmvfc event struct
@@ -897,10 +923,7 @@ static void ibmvfc_fail_request(struct ibmvfc_event *evt, int error_code)
} else
evt->xfer_iu->mad_common.status = cpu_to_be16(IBMVFC_MAD_DRIVER_FAILED);

- list_del(&evt->queue_list);
del_timer(&evt->timer);
- ibmvfc_trc_end(evt);
- evt->done(evt);
}

/**
@@ -914,10 +937,14 @@ static void ibmvfc_fail_request(struct ibmvfc_event *evt, int error_code)
static void ibmvfc_purge_requests(struct ibmvfc_host *vhost, int error_code)
{
struct ibmvfc_event *evt, *pos;
+ unsigned long flags;

ibmvfc_dbg(vhost, "Purging all requests\n");
+ spin_lock_irqsave(&vhost->crq.l_lock, flags);
list_for_each_entry_safe(evt, pos, &vhost->crq.sent, queue_list)
ibmvfc_fail_request(evt, error_code);
+ list_splice_init(&vhost->crq.sent, &vhost->purge);
+ spin_unlock_irqrestore(&vhost->crq.l_lock, flags);
}

/**
@@ -1314,6 +1341,7 @@ static int ibmvfc_init_event_pool(struct ibmvfc_host *vhost,

INIT_LIST_HEAD(&queue->sent);
INIT_LIST_HEAD(&queue->free);
+ spin_lock_init(&queue->l_lock);

for (i = 0; i < pool->size; ++i) {
struct ibmvfc_event *evt = &pool->events[i];
@@ -1368,11 +1396,14 @@ static void ibmvfc_free_event_pool(struct ibmvfc_host *vhost,
static struct ibmvfc_event *ibmvfc_get_event(struct ibmvfc_queue *queue)
{
struct ibmvfc_event *evt;
+ unsigned long flags;

+ spin_lock_irqsave(&queue->l_lock, flags);
BUG_ON(list_empty(&queue->free));
evt = list_entry(queue->free.next, struct ibmvfc_event, queue_list);
atomic_set(&evt->free, 0);
list_del(&evt->queue_list);
+ spin_unlock_irqrestore(&queue->l_lock, flags);
return evt;
}

@@ -1506,6 +1537,7 @@ static int ibmvfc_send_event(struct ibmvfc_event *evt,
struct ibmvfc_host *vhost, unsigned long timeout)
{
__be64 *crq_as_u64 = (__be64 *) &evt->crq;
+ unsigned long flags;
int rc;

/* Copy the IU into the transfer area */
@@ -1517,7 +1549,6 @@ static int ibmvfc_send_event(struct ibmvfc_event *evt,
else
BUG();

- list_add_tail(&evt->queue_list, &evt->queue->sent);
timer_setup(&evt->timer, ibmvfc_timeout, 0);

if (timeout) {
@@ -1525,11 +1556,15 @@ static int ibmvfc_send_event(struct ibmvfc_event *evt,
add_timer(&evt->timer);
}

+ spin_lock_irqsave(&evt->queue->l_lock, flags);
+ list_add_tail(&evt->queue_list, &evt->queue->sent);
+
mb();

if ((rc = ibmvfc_send_crq(vhost, be64_to_cpu(crq_as_u64[0]),
be64_to_cpu(crq_as_u64[1])))) {
list_del(&evt->queue_list);
+ spin_unlock_irqrestore(&evt->queue->l_lock, flags);
del_timer(&evt->timer);

/* If send_crq returns H_CLOSED, return SCSI_MLQUEUE_HOST_BUSY.
@@ -1554,8 +1589,10 @@ static int ibmvfc_send_event(struct ibmvfc_event *evt,
evt->xfer_iu->mad_common.status = cpu_to_be16(IBMVFC_MAD_CRQ_ERROR);

evt->done(evt);
- } else
+ } else {
+ spin_unlock_irqrestore(&evt->queue->l_lock, flags);
ibmvfc_trc_start(evt);
+ }

return 0;
}
@@ -1663,9 +1700,6 @@ static void ibmvfc_scsi_done(struct ibmvfc_event *evt)
cmnd->scsi_done(cmnd);
}

- if (evt->eh_comp)
- complete(evt->eh_comp);
-
ibmvfc_free_event(evt);
}

@@ -2219,28 +2253,28 @@ static int ibmvfc_wait_for_ops(struct ibmvfc_host *vhost, void *device,
ENTER;
do {
wait = 0;
- spin_lock_irqsave(vhost->host->host_lock, flags);
+ spin_lock_irqsave(&vhost->crq.l_lock, flags);
list_for_each_entry(evt, &vhost->crq.sent, queue_list) {
if (match(evt, device)) {
evt->eh_comp = &comp;
wait++;
}
}
- spin_unlock_irqrestore(vhost->host->host_lock, flags);
+ spin_unlock_irqrestore(&vhost->crq.l_lock, flags);

if (wait) {
timeout = wait_for_completion_timeout(&comp, timeout);

if (!timeout) {
wait = 0;
- spin_lock_irqsave(vhost->host->host_lock, flags);
+ spin_lock_irqsave(&vhost->crq.l_lock, flags);
list_for_each_entry(evt, &vhost->crq.sent, queue_list) {
if (match(evt, device)) {
evt->eh_comp = NULL;
wait++;
}
}
- spin_unlock_irqrestore(vhost->host->host_lock, flags);
+ spin_unlock_irqrestore(&vhost->crq.l_lock, flags);
if (wait)
dev_err(vhost->dev, "Timed out waiting for aborted commands\n");
LEAVE;
@@ -2277,14 +2311,16 @@ static int ibmvfc_cancel_all(struct scsi_device *sdev, int type)
u16 status;

ENTER;
- spin_lock_irqsave(vhost->host->host_lock, flags);
found_evt = NULL;
+ spin_lock_irqsave(vhost->host->host_lock, flags);
+ spin_lock(&vhost->crq.l_lock);
list_for_each_entry(evt, &vhost->crq.sent, queue_list) {
if (evt->cmnd && evt->cmnd->device == sdev) {
found_evt = evt;
break;
}
}
+ spin_unlock(&vhost->crq.l_lock);

if (!found_evt) {
if (vhost->log_level > IBMVFC_DEFAULT_LOG_LEVEL)
@@ -2414,14 +2450,16 @@ static int ibmvfc_abort_task_set(struct scsi_device *sdev)
unsigned long flags, timeout = IBMVFC_ABORT_TIMEOUT;
int rsp_code = 0;

- spin_lock_irqsave(vhost->host->host_lock, flags);
found_evt = NULL;
+ spin_lock_irqsave(vhost->host->host_lock, flags);
+ spin_lock(&vhost->crq.l_lock);
list_for_each_entry(evt, &vhost->crq.sent, queue_list) {
if (evt->cmnd && evt->cmnd->device == sdev) {
found_evt = evt;
break;
}
}
+ spin_unlock(&vhost->crq.l_lock);

if (!found_evt) {
if (vhost->log_level > IBMVFC_DEFAULT_LOG_LEVEL)
@@ -2935,7 +2973,9 @@ static void ibmvfc_handle_crq(struct ibmvfc_crq *crq, struct ibmvfc_host *vhost)
}

del_timer(&evt->timer);
+ spin_lock(&evt->queue->l_lock);
list_del(&evt->queue_list);
+ spin_unlock(&evt->queue->l_lock);
ibmvfc_trc_end(evt);
evt->done(evt);
}
@@ -3328,6 +3368,7 @@ static void ibmvfc_tasklet(void *data)
int done = 0;

spin_lock_irqsave(vhost->host->host_lock, flags);
+ spin_lock(vhost->crq.q_lock);
while (!done) {
/* Pull all the valid messages off the async CRQ */
while ((async = ibmvfc_next_async_crq(vhost)) != NULL) {
@@ -3358,6 +3399,7 @@ static void ibmvfc_tasklet(void *data)
done = 1;
}

+ spin_unlock(vhost->crq.q_lock);
spin_unlock_irqrestore(vhost->host->host_lock, flags);
}

@@ -4734,6 +4776,7 @@ static void ibmvfc_do_work(struct ibmvfc_host *vhost)
struct ibmvfc_target *tgt;
unsigned long flags;
struct fc_rport *rport;
+ LIST_HEAD(purge);
int rc;

ibmvfc_log_ae(vhost, vhost->events_to_log);
@@ -4746,6 +4789,8 @@ static void ibmvfc_do_work(struct ibmvfc_host *vhost)
break;
case IBMVFC_HOST_ACTION_RESET:
vhost->action = IBMVFC_HOST_ACTION_TGT_DEL;
+ list_splice_init(&vhost->purge, &purge);
+ ibmvfc_complete_purge(&purge);
spin_unlock_irqrestore(vhost->host->host_lock, flags);
rc = ibmvfc_reset_crq(vhost);
spin_lock_irqsave(vhost->host->host_lock, flags);
@@ -4759,6 +4804,8 @@ static void ibmvfc_do_work(struct ibmvfc_host *vhost)
break;
case IBMVFC_HOST_ACTION_REENABLE:
vhost->action = IBMVFC_HOST_ACTION_TGT_DEL;
+ list_splice_init(&vhost->purge, &purge);
+ ibmvfc_complete_purge(&purge);
spin_unlock_irqrestore(vhost->host->host_lock, flags);
rc = ibmvfc_reenable_crq_queue(vhost);
spin_lock_irqsave(vhost->host->host_lock, flags);
@@ -4936,6 +4983,9 @@ static int ibmvfc_alloc_queue(struct ibmvfc_host *vhost,
size_t fmt_size;

ENTER;
+ spin_lock_init(&queue->_lock);
+ queue->q_lock = &queue->_lock;
+
switch (fmt) {
case IBMVFC_CRQ_FMT:
fmt_size = sizeof(*queue->msgs.crq);
@@ -5098,6 +5148,7 @@ static int ibmvfc_alloc_mem(struct ibmvfc_host *vhost)

vhost->trace = kcalloc(IBMVFC_NUM_TRACE_ENTRIES,
sizeof(struct ibmvfc_trace_entry), GFP_KERNEL);
+ atomic_set(&vhost->trace_index, -1);

if (!vhost->trace)
goto free_disc_buffer;
@@ -5214,6 +5265,7 @@ static int ibmvfc_probe(struct vio_dev *vdev, const struct vio_device_id *id)

vhost = shost_priv(shost);
INIT_LIST_HEAD(&vhost->targets);
+ INIT_LIST_HEAD(&vhost->purge);
sprintf(vhost->name, IBMVFC_NAME);
vhost->host = shost;
vhost->dev = dev;
@@ -5298,6 +5350,7 @@ static int ibmvfc_probe(struct vio_dev *vdev, const struct vio_device_id *id)
static int ibmvfc_remove(struct vio_dev *vdev)
{
struct ibmvfc_host *vhost = dev_get_drvdata(&vdev->dev);
+ LIST_HEAD(purge);
unsigned long flags;

ENTER;
@@ -5315,6 +5368,8 @@ static int ibmvfc_remove(struct vio_dev *vdev)

spin_lock_irqsave(vhost->host->host_lock, flags);
ibmvfc_purge_requests(vhost, DID_ERROR);
+ list_splice_init(&vhost->purge, &purge);
+ ibmvfc_complete_purge(&purge);
spin_unlock_irqrestore(vhost->host->host_lock, flags);
ibmvfc_free_event_pool(vhost, &vhost->crq);

diff --git a/drivers/scsi/ibmvscsi/ibmvfc.h b/drivers/scsi/ibmvscsi/ibmvfc.h
index 61c73b6f7a77..faf5b50d65b9 100644
--- a/drivers/scsi/ibmvscsi/ibmvfc.h
+++ b/drivers/scsi/ibmvscsi/ibmvfc.h
@@ -768,10 +768,13 @@ struct ibmvfc_queue {
dma_addr_t msg_token;
enum ibmvfc_msg_fmt fmt;
int size, cur;
+ spinlock_t _lock;
+ spinlock_t *q_lock;

struct ibmvfc_event_pool evt_pool;
struct list_head sent;
struct list_head free;
+ spinlock_t l_lock;
};

enum ibmvfc_host_action {
@@ -808,11 +811,13 @@ struct ibmvfc_host {
enum ibmvfc_host_action action;
#define IBMVFC_NUM_TRACE_INDEX_BITS 8
#define IBMVFC_NUM_TRACE_ENTRIES (1 << IBMVFC_NUM_TRACE_INDEX_BITS)
+#define IBMVFC_TRACE_INDEX_MASK (IBMVFC_NUM_TRACE_ENTRIES - 1)
#define IBMVFC_TRACE_SIZE (sizeof(struct ibmvfc_trace_entry) * IBMVFC_NUM_TRACE_ENTRIES)
struct ibmvfc_trace_entry *trace;
- u32 trace_index:IBMVFC_NUM_TRACE_INDEX_BITS;
+ atomic_t trace_index;
int num_targets;
struct list_head targets;
+ struct list_head purge;
struct device *dev;
struct dma_pool *sg_pool;
mempool_t *tgt_pool;
--
2.27.0