[PATCH RFC v2 12/24] hpsa: use reserved commands

John Garry
2020-03-10T16:32:44Z

From: Hannes Reinecke <hare@suse.com>

Enable the use of reserved commands, and drop the hand-crafted
command allocation.

Signed-off-by: Hannes Reinecke <hare@suse.com>
---
drivers/scsi/hpsa.c | 147 ++++++++++++++------------------------------
drivers/scsi/hpsa.h | 1 -
2 files changed, 45 insertions(+), 103 deletions(-)

diff --git a/drivers/scsi/hpsa.c b/drivers/scsi/hpsa.c
index 703f824584fe..c14dd4b6e598 100644
--- a/drivers/scsi/hpsa.c
+++ b/drivers/scsi/hpsa.c
@@ -244,10 +244,6 @@ static struct hpsa_scsi_dev_t
*hpsa_find_device_by_sas_rphy(struct ctlr_info *h,
struct sas_rphy *rphy);

-#define SCSI_CMD_BUSY ((struct scsi_cmnd *)&hpsa_cmd_busy)
-static const struct scsi_cmnd hpsa_cmd_busy;
-#define SCSI_CMD_IDLE ((struct scsi_cmnd *)&hpsa_cmd_idle)
-static const struct scsi_cmnd hpsa_cmd_idle;
static int number_of_controllers;

static irqreturn_t do_hpsa_intr_intx(int irq, void *dev_id);
@@ -342,7 +338,7 @@ static inline struct ctlr_info *shost_to_hba(struct Scsi_Host *sh)

static inline bool hpsa_is_cmd_idle(struct CommandList *c)
{
- return c->scsi_cmd == SCSI_CMD_IDLE;
+ return c->scsi_cmd == NULL;
}

/* extract sense key, asc, and ascq from sense data. -1 means invalid. */
@@ -2445,7 +2441,12 @@ static void hpsa_cmd_resolve_events(struct ctlr_info *h,
* this command has completed. Then, check to see if the handler is
* waiting for this command, and, if so, wake it.
*/
- c->scsi_cmd = SCSI_CMD_IDLE;
+ if (c->scsi_cmd && c->cmd_type == CMD_IOCTL_PEND) {
+ struct scsi_cmnd *scmd = c->scsi_cmd;
+
+ scsi_put_reserved_cmd(scmd);
+ }
+ c->scsi_cmd = NULL;
mb(); /* Declare command idle before checking for pending events. */
if (dev) {
atomic_dec(&dev->commands_outstanding);
@@ -5502,7 +5503,6 @@ static void hpsa_cmd_init(struct ctlr_info *h, int index,
c->ErrDesc.Addr = cpu_to_le64((u64) err_dma_handle);
c->ErrDesc.Len = cpu_to_le32((u32) sizeof(*c->err_info));
c->h = h;
- c->scsi_cmd = SCSI_CMD_IDLE;
}

static void hpsa_preinitialize_commands(struct ctlr_info *h)
@@ -5803,6 +5803,7 @@ static int hpsa_scsi_host_alloc(struct ctlr_info *h)
sh->max_lun = HPSA_MAX_LUN;
sh->max_id = HPSA_MAX_LUN;
sh->can_queue = h->nr_cmds - HPSA_NRESERVED_CMDS;
+ sh->nr_reserved_cmds = HPSA_NRESERVED_CMDS;
sh->cmd_per_lun = sh->can_queue;
sh->sg_tablesize = h->maxsgentries;
sh->transportt = hpsa_sas_transport_template;
@@ -5846,23 +5847,6 @@ static int hpsa_scsi_add_host(struct ctlr_info *h)
return 0;
}

-/*
- * The block layer has already gone to the trouble of picking out a unique,
- * small-integer tag for this request. We use an offset from that value as
- * an index to select our command block. (The offset allows us to reserve the
- * low-numbered entries for our own uses.)
- */
-static int hpsa_get_cmd_index(struct scsi_cmnd *scmd)
-{
- int idx = scmd->request->tag;
-
- if (idx < 0)
- return idx;
-
- /* Offset to leave space for internal cmds. */
- return idx += HPSA_NRESERVED_CMDS;
-}
-
/*
* Send a TEST_UNIT_READY command to the specified LUN using the specified
* reply queue; returns zero if the unit is ready, and non-zero otherwise.
@@ -6019,7 +6003,7 @@ static int hpsa_eh_device_reset_handler(struct scsi_cmnd *scsicmd)
if (lockup_detected(h)) {
snprintf(msg, sizeof(msg),
"cmd %d RESET FAILED, lockup detected",
- hpsa_get_cmd_index(scsicmd));
+ scsicmd->request->tag);
hpsa_show_dev_msg(KERN_WARNING, h, dev, msg);
rc = FAILED;
goto return_reset_status;
@@ -6029,7 +6013,7 @@ static int hpsa_eh_device_reset_handler(struct scsi_cmnd *scsicmd)
if (detect_controller_lockup(h)) {
snprintf(msg, sizeof(msg),
"cmd %d RESET FAILED, new lockup detected",
- hpsa_get_cmd_index(scsicmd));
+ scsicmd->request->tag);
hpsa_show_dev_msg(KERN_WARNING, h, dev, msg);
rc = FAILED;
goto return_reset_status;
@@ -6091,12 +6075,12 @@ static int hpsa_eh_device_reset_handler(struct scsi_cmnd *scsicmd)
static struct CommandList *cmd_tagged_alloc(struct ctlr_info *h,
struct scsi_cmnd *scmd)
{
- int idx = hpsa_get_cmd_index(scmd);
+ int idx = scmd->request->tag;
struct CommandList *c = h->cmd_pool + idx;

- if (idx < HPSA_NRESERVED_CMDS || idx >= h->nr_cmds) {
+ if (idx < 0 || idx >= h->nr_cmds) {
dev_err(&h->pdev->dev, "Bad block tag: %d not in [%d..%d]\n",
- idx, HPSA_NRESERVED_CMDS, h->nr_cmds - 1);
+ idx, 0, h->nr_cmds - 1);
/* The index value comes from the block layer, so if it's out of
* bounds, it's probably not our bug.
*/
@@ -6133,81 +6117,49 @@ static void cmd_tagged_free(struct ctlr_info *h, struct CommandList *c)
* else to free it, because it is accessed by index.
*/
(void)atomic_dec(&c->refcount);
+ c->scsi_cmd = NULL;
}

-/*
- * For operations that cannot sleep, a command block is allocated at init,
- * and managed by cmd_alloc() and cmd_free() using a simple bitmap to track
- * which ones are free or in use. Lock must be held when calling this.
- * cmd_free() is the complement.
- * This function never gives up and returns NULL. If it hangs,
- * another thread must call cmd_free() to free some tags.
- */
-
static struct CommandList *cmd_alloc(struct ctlr_info *h)
{
+ struct scsi_cmnd *scmd;
struct CommandList *c;
- int refcount, i;
- int offset = 0;
-
- /*
- * There is some *extremely* small but non-zero chance that that
- * multiple threads could get in here, and one thread could
- * be scanning through the list of bits looking for a free
- * one, but the free ones are always behind him, and other
- * threads sneak in behind him and eat them before he can
- * get to them, so that while there is always a free one, a
- * very unlucky thread might be starved anyway, never able to
- * beat the other threads. In reality, this happens so
- * infrequently as to be indistinguishable from never.
- *
- * Note that we start allocating commands before the SCSI host structure
- * is initialized. Since the search starts at bit zero, this
- * all works, since we have at least one command structure available;
- * however, it means that the structures with the low indexes have to be
- * reserved for driver-initiated requests, while requests from the block
- * layer will use the higher indexes.
- */
+ int idx;

- for (;;) {
- i = find_next_zero_bit(h->cmd_pool_bits,
- HPSA_NRESERVED_CMDS,
- offset);
- if (unlikely(i >= HPSA_NRESERVED_CMDS)) {
- offset = 0;
- continue;
- }
- c = h->cmd_pool + i;
- refcount = atomic_inc_return(&c->refcount);
- if (unlikely(refcount > 1)) {
- cmd_free(h, c); /* already in use */
- offset = (i + 1) % HPSA_NRESERVED_CMDS;
- continue;
- }
- set_bit(i & (BITS_PER_LONG - 1),
- h->cmd_pool_bits + (i / BITS_PER_LONG));
- break; /* it's ours now. */
+ scmd = scsi_get_reserved_cmd(h->scsi_host);
+ if (!scmd) {
+ dev_warn(&h->pdev->dev, "failed to allocate reserved cmd\n");
+ return NULL;
+ }
+ idx = scmd->request->tag;
+ c = cmd_tagged_alloc(h, scmd);
+ if (!c) {
+ dev_warn(&h->pdev->dev, "failed to allocate reserved cmd %u\n",
+ idx);
+ scsi_put_reserved_cmd(scmd);
+ return NULL;
}
- hpsa_cmd_partial_init(h, i, c);
- c->device = NULL;
- return c;
+ hpsa_cmd_partial_init(h, idx, c);
+ c->scsi_cmd = scmd;
+ c->device = NULL;
+ dev_dbg(&h->pdev->dev, "using reserved cmd %u\n", idx);
+ return c;
}

-/*
- * This is the complementary operation to cmd_alloc(). Note, however, in some
- * corner cases it may also be used to free blocks allocated by
- * cmd_tagged_alloc() in which case the ref-count decrement does the trick and
- * the clear-bit is harmless.
- */
static void cmd_free(struct ctlr_info *h, struct CommandList *c)
{
- if (atomic_dec_and_test(&c->refcount)) {
- int i;
-
- i = c - h->cmd_pool;
- clear_bit(i & (BITS_PER_LONG - 1),
- h->cmd_pool_bits + (i / BITS_PER_LONG));
+ struct scsi_cmnd *scmd = c->scsi_cmd;
+
+ if (!scmd) {
+ dev_warn(&h->pdev->dev, "freeing idle cmd\n");
+ return;
}
+ cmd_tagged_free(h, c);
+ if (c->cmd_type == CMD_IOCTL_PEND && scmd) {
+ dev_dbg(&h->pdev->dev, "returning reserved cmd %u\n",
+ scmd->request->tag);
+ scsi_put_reserved_cmd(scmd);
+ }
}

#ifdef CONFIG_COMPAT
@@ -6393,7 +6345,6 @@ static int hpsa_passthru_ioctl(struct ctlr_info *h, void __user *argp)

/* Fill in the command type */
c->cmd_type = CMD_IOCTL_PEND;
- c->scsi_cmd = SCSI_CMD_BUSY;
/* Fill in Command Header */
c->Header.ReplyQueue = 0; /* unused in simple mode */
if (iocommand.buf_size > 0) { /* buffer to fill */
@@ -6525,7 +6476,6 @@ static int hpsa_big_passthru_ioctl(struct ctlr_info *h, void __user *argp)
c = cmd_alloc(h);

c->cmd_type = CMD_IOCTL_PEND;
- c->scsi_cmd = SCSI_CMD_BUSY;
c->Header.ReplyQueue = 0;
c->Header.SGList = (u8) sg_used;
c->Header.SGTotal = cpu_to_le16(sg_used);
@@ -6669,7 +6619,6 @@ static int fill_cmd(struct CommandList *c, u8 cmd, struct ctlr_info *h,
enum dma_data_direction dir = DMA_NONE;

c->cmd_type = CMD_IOCTL_PEND;
- c->scsi_cmd = SCSI_CMD_BUSY;
c->Header.ReplyQueue = 0;
if (buff != NULL && size > 0) {
c->Header.SGList = 1;
@@ -7982,8 +7931,6 @@ static int hpsa_init_reset_devices(struct pci_dev *pdev, u32 board_id)

static void hpsa_free_cmd_pool(struct ctlr_info *h)
{
- kfree(h->cmd_pool_bits);
- h->cmd_pool_bits = NULL;
if (h->cmd_pool) {
dma_free_coherent(&h->pdev->dev,
h->nr_cmds * sizeof(struct CommandList),
@@ -8004,17 +7951,13 @@ static void hpsa_free_cmd_pool(struct ctlr_info *h)

static int hpsa_alloc_cmd_pool(struct ctlr_info *h)
{
- h->cmd_pool_bits = kcalloc(DIV_ROUND_UP(h->nr_cmds, BITS_PER_LONG),
- sizeof(unsigned long),
- GFP_KERNEL);
h->cmd_pool = dma_alloc_coherent(&h->pdev->dev,
h->nr_cmds * sizeof(*h->cmd_pool),
&h->cmd_pool_dhandle, GFP_KERNEL);
h->errinfo_pool = dma_alloc_coherent(&h->pdev->dev,
h->nr_cmds * sizeof(*h->errinfo_pool),
&h->errinfo_pool_dhandle, GFP_KERNEL);
- if ((h->cmd_pool_bits == NULL)
- || (h->cmd_pool == NULL)
+ if ((h->cmd_pool == NULL)
|| (h->errinfo_pool == NULL)) {
dev_err(&h->pdev->dev, "out of memory in %s", __func__);
goto clean_up;
diff --git a/drivers/scsi/hpsa.h b/drivers/scsi/hpsa.h
index f8c88fc7b80a..70addb024ebb 100644
--- a/drivers/scsi/hpsa.h
+++ b/drivers/scsi/hpsa.h
@@ -205,7 +205,6 @@ struct ctlr_info {
dma_addr_t ioaccel2_cmd_pool_dhandle;
struct ErrorInfo *errinfo_pool;
dma_addr_t errinfo_pool_dhandle;
- unsigned long *cmd_pool_bits;
int scan_finished;
u8 scan_waiting : 1;
spinlock_t scan_lock;
--
2.17.1