[PATCH v24 41/46] sg: track lowest inactive and await indexes

Douglas Gilbert
2022-04-11T02:30:52Z

Use two integers in the sg_fd structure to track recent and lowest
xarray indexes that have become inactive or await a foreground
receive. This is used to shorten the number of xarray iterations
required prior to a match when queue (IO) depths are large, say
128.

Replace the req_cnt atomic in struct sg_fd with the inactives
atomic. With large queues, cycles were wasted checking the request
xarray for any inactives when there were none to be found.

Rename the sg_rq_state_chg_*() functions to sg_rq_chg_state_*()
since too many things start with "sg_rq_state". Also the new
function names emphasize the change part a little more.

Rename the struct request pointer from rq to rqq and when it read
and written to sg_request::rqq use READ_ONCE() and WRITE_ONCE()
macros.

Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Douglas Gilbert <dgilbert@interlog.com>
---
drivers/scsi/sg.c | 354 +++++++++++++++++++++++++++-------------------
1 file changed, 206 insertions(+), 148 deletions(-)

diff --git a/drivers/scsi/sg.c b/drivers/scsi/sg.c
index b9fdfcfc18ee..71d86537601d 100644
--- a/drivers/scsi/sg.c
+++ b/drivers/scsi/sg.c
@@ -119,6 +119,7 @@ enum sg_rq_state { /* N.B. sg_rq_state_arr assumes SG_RS_AWAIT_RCV==2 */
#define SG_FRQ_DEACT_ORPHAN 6 /* not keeping orphan so de-activate */
#define SG_FRQ_RECEIVING 7 /* guard against multiple receivers */
#define SG_FRQ_FOR_MMAP 8 /* request needs PAGE_SIZE elements */
+#define SG_FRQ_COUNT_ACTIVE 9 /* sfp->submitted + waiting active */

/* Bit positions (flags) for sg_fd::ffd_bm bitmask follow */
#define SG_FFD_FORCE_PACKID 0 /* receive only given pack_id/tag */
@@ -217,7 +218,7 @@ struct sg_request { /* active SCSI command or inactive request */
unsigned long frq_bm[1]; /* see SG_FRQ_* defines above */
u8 *sense_bp; /* mempool alloc-ed sense buffer, as needed */
struct sg_fd *parentfp; /* pointer to owning fd, even when on fl */
- struct request *rq; /* released in sg_rq_end_io(), bio kept */
+ struct request *rqq; /* released in sg_rq_end_io(), bio kept */
struct bio *bio; /* kept until this req -->SG_RS_INACTIVE */
struct execute_work ew_orph; /* harvest orphan request */
};
@@ -228,11 +229,12 @@ struct sg_fd { /* holds the state of a file descriptor */
struct mutex f_mutex; /* serialize ioctls on this fd */
int timeout; /* defaults to SG_DEFAULT_TIMEOUT */
int timeout_user; /* defaults to SG_DEFAULT_TIMEOUT_USER */
- int prev_used_idx; /* previous used index */
+ int low_used_idx; /* previous or lower used index */
+ int low_await_idx; /* previous or lower await index */
u32 idx; /* my index within parent's sfp_arr */
atomic_t submitted; /* number inflight or awaiting receive */
atomic_t waiting; /* number of requests awaiting receive */
- atomic_t req_cnt; /* number of requests */
+ atomic_t inactives; /* number of inactive requests */
int sgat_elem_sz; /* initialized to scatter_elem_sz */
int mmap_sz; /* byte size of previous mmap() call */
unsigned long ffd_bm[1]; /* see SG_FFD_* defines above */
@@ -889,11 +891,13 @@ sg_rq_state_fail_msg(struct sg_fd *sfp, enum sg_rq_state exp_old_st,
}
#endif

+/* Functions ending in '_ulck' assume sfp->xa_lock held by caller. */
static void
-sg_rq_state_force(struct sg_request *srp, enum sg_rq_state new_st)
+sg_rq_chg_state_force_ulck(struct sg_request *srp, enum sg_rq_state new_st)
{
bool prev, want;
- struct xarray *xafp = &srp->parentfp->srp_arr;
+ struct sg_fd *sfp = srp->parentfp;
+ struct xarray *xafp = &sfp->srp_arr;

atomic_set(&srp->rq_st, new_st);
want = (new_st == SG_RS_AWAIT_RCV);
@@ -907,15 +911,21 @@ sg_rq_state_force(struct sg_request *srp, enum sg_rq_state new_st)
want = (new_st == SG_RS_INACTIVE);
prev = xa_get_mark(xafp, srp->rq_idx, SG_XA_RQ_INACTIVE);
if (prev != want) {
- if (want)
+ if (want) {
+ int prev_idx = READ_ONCE(sfp->low_used_idx);
+
+ if (prev_idx < 0 || srp->rq_idx < prev_idx ||
+ !xa_get_mark(xafp, prev_idx, SG_XA_RQ_INACTIVE))
+ WRITE_ONCE(sfp->low_used_idx, srp->rq_idx);
__xa_set_mark(xafp, srp->rq_idx, SG_XA_RQ_INACTIVE);
- else
+ } else {
__xa_clear_mark(xafp, srp->rq_idx, SG_XA_RQ_INACTIVE);
+ }
}
}

static void
-sg_rq_state_helper(struct xarray *xafp, struct sg_request *srp, int indic)
+sg_rq_chg_state_help(struct xarray *xafp, struct sg_request *srp, int indic)
{
if (indic & 1) /* from inactive state */
__xa_clear_mark(xafp, srp->rq_idx, SG_XA_RQ_INACTIVE);
@@ -944,45 +954,53 @@ static const int sg_rq_state_mul2arr[] = {2, 0, 8, 0};
* spinlock is held.
*/
static int
-sg_rq_state_chg(struct sg_request *srp, enum sg_rq_state old_st,
+sg_rq_chg_state(struct sg_request *srp, enum sg_rq_state old_st,
enum sg_rq_state new_st)
{
enum sg_rq_state act_old_st;
- int indic;
- unsigned long iflags;
+ int indic = sg_rq_state_arr[(int)old_st] + sg_rq_state_mul2arr[(int)new_st];
struct sg_fd *sfp = srp->parentfp;
- struct xarray *xafp = &sfp->srp_arr;

- indic = sg_rq_state_arr[(int)old_st] +
- sg_rq_state_mul2arr[(int)new_st];
- act_old_st = (enum sg_rq_state)atomic_cmpxchg(&srp->rq_st, old_st,
- new_st);
- if (act_old_st != old_st) {
- SG_LOG(1, sfp, "%s: unexpected old state: %s\n", __func__,
- sg_rq_st_str(act_old_st, false));
- return -EPROTOTYPE; /* only used for this error type */
- }
if (indic) {
+ unsigned long iflags;
+ struct xarray *xafp = &sfp->srp_arr;
+
xa_lock_irqsave(xafp, iflags);
- if (new_st == SG_RS_INACTIVE)
- WRITE_ONCE(sfp->prev_used_idx, srp->rq_idx);
- sg_rq_state_helper(xafp, srp, indic);
+ act_old_st = (enum sg_rq_state)atomic_cmpxchg_relaxed(&srp->rq_st, old_st, new_st);
+ if (unlikely(act_old_st != old_st)) {
+ xa_unlock_irqrestore(xafp, iflags);
+ SG_LOG(1, sfp, "%s: unexpected old state: %s\n", __func__,
+ sg_rq_st_str(act_old_st, false));
+ return -EPROTOTYPE; /* only used for this error type */
+ }
+ if (new_st == SG_RS_INACTIVE) {
+ int prev_idx = READ_ONCE(sfp->low_used_idx);
+
+ if (prev_idx < 0 || srp->rq_idx < prev_idx ||
+ !xa_get_mark(xafp, prev_idx, SG_XA_RQ_INACTIVE))
+ WRITE_ONCE(sfp->low_used_idx, srp->rq_idx);
+ }
+ sg_rq_chg_state_help(xafp, srp, indic);
xa_unlock_irqrestore(xafp, iflags);
+ } else {
+ act_old_st = (enum sg_rq_state)atomic_cmpxchg(&srp->rq_st, old_st, new_st);
+ if (unlikely(act_old_st != old_st)) {
+ SG_LOG(1, sfp, "%s: unexpected old state: %s\n", __func__,
+ sg_rq_st_str(act_old_st, false));
+ return -EPROTOTYPE; /* only used for this error type */
+ }
}
return 0;
}

static void
-sg_rq_state_chg_force(struct sg_request *srp, enum sg_rq_state new_st)
+sg_rq_chg_state_force(struct sg_request *srp, enum sg_rq_state new_st)
{
unsigned long iflags;
- struct sg_fd *sfp = srp->parentfp;
- struct xarray *xafp = &sfp->srp_arr;
+ struct xarray *xafp = &srp->parentfp->srp_arr;

xa_lock_irqsave(xafp, iflags);
- if (new_st == SG_RS_INACTIVE)
- WRITE_ONCE(sfp->prev_used_idx, srp->rq_idx);
- sg_rq_state_force(srp, new_st);
+ sg_rq_chg_state_force_ulck(srp, new_st);
xa_unlock_irqrestore(xafp, iflags);
}

@@ -1006,12 +1024,14 @@ sg_execute_cmd(struct sg_fd *sfp, struct sg_request *srp)
at_head = !(srp->rq_flags & SG_FLAG_Q_AT_TAIL);

kref_get(&sfp->f_ref); /* sg_rq_end_io() does kref_put(). */
- sg_rq_state_chg_force(srp, SG_RS_INFLIGHT);
+ sg_rq_chg_state_force(srp, SG_RS_INFLIGHT);

/* >>>>>>> send cmd/req off to other levels <<<<<<<< */
- if (!sync)
+ if (!sync) {
atomic_inc(&sfp->submitted);
- blk_execute_rq_nowait(srp->rq, (int)at_head, sg_rq_end_io);
+ set_bit(SG_FRQ_COUNT_ACTIVE, srp->frq_bm);
+ }
+ blk_execute_rq_nowait(READ_ONCE(srp->rqq), (int)at_head, sg_rq_end_io);
}

/*
@@ -1086,7 +1106,7 @@ sg_common_write(struct sg_comm_wr_t *cwrp)
res = -ENODEV;
goto err_out;
}
- srp->rq->timeout = cwrp->timeout;
+ READ_ONCE(srp->rqq)->timeout = cwrp->timeout;
sg_execute_cmd(fp, srp);
return srp;
err_out:
@@ -1655,7 +1675,7 @@ sg_fill_request_element(struct sg_fd *sfp, struct sg_request *srp,
static inline bool
sg_rq_landed(struct sg_device *sdp, struct sg_request *srp)
{
- return atomic_read(&srp->rq_st) != SG_RS_INFLIGHT ||
+ return atomic_read_acquire(&srp->rq_st) != SG_RS_INFLIGHT ||
unlikely(SG_IS_DETACHING(sdp));
}

@@ -1671,6 +1691,8 @@ sg_wait_event_srp(struct file *filp, struct sg_fd *sfp, void __user *p,
enum sg_rq_state sr_st;
struct sg_device *sdp = sfp->parentdp;

+ if (atomic_read(&srp->rq_st) != SG_RS_INFLIGHT)
+ goto skip_wait; /* and skip _acquire() */
SG_LOG(3, sfp, "%s: about to wait_event...()\n", __func__);
/* usually will be woken up by sg_rq_end_io() callback */
res = wait_event_interruptible(sfp->read_wait,
@@ -1683,14 +1705,16 @@ sg_wait_event_srp(struct file *filp, struct sg_fd *sfp, void __user *p,
__func__, res);
return res;
}
+skip_wait:
if (unlikely(SG_IS_DETACHING(sdp))) {
- atomic_set(&srp->rq_st, SG_RS_INACTIVE);
+ sg_rq_chg_state_force(srp, SG_RS_INACTIVE);
+ atomic_inc(&sfp->inactives);
return -ENODEV;
}
sr_st = atomic_read(&srp->rq_st);
if (unlikely(sr_st != SG_RS_AWAIT_RCV))
return -EPROTO; /* Logic error */
- res = sg_rq_state_chg(srp, sr_st, SG_RS_BUSY);
+ res = sg_rq_chg_state(srp, sr_st, SG_RS_BUSY);
if (unlikely(res)) {
#if IS_ENABLED(SG_LOG_ACTIVE)
sg_rq_state_fail_msg(sfp, sr_st, SG_RS_BUSY, __func__);
@@ -1948,7 +1972,10 @@ sg_ioctl_common(struct file *filp, struct sg_device *sdp, struct sg_fd *sfp,
SG_LOG(3, sfp, "%s: SG_GET_PACK_ID=%d\n", __func__, val);
return put_user(val, ip);
case SG_GET_NUM_WAITING:
- return put_user(atomic_read(&sfp->waiting), ip);
+ val = atomic_read(&sfp->waiting);
+ if (val)
+ return put_user(val, ip);
+ return put_user(atomic_read_acquire(&sfp->waiting), ip);
case SG_GET_SG_TABLESIZE:
SG_LOG(3, sfp, "%s: SG_GET_SG_TABLESIZE=%d\n", __func__,
sdp->max_sgat_sz);
@@ -2136,11 +2163,16 @@ sg_ioctl(struct file *filp, unsigned int cmd_in, unsigned long arg)
static __poll_t
sg_poll(struct file *filp, poll_table * wait)
{
+ int num;
__poll_t p_res = 0;
struct sg_fd *sfp = filp->private_data;

- poll_wait(filp, &sfp->read_wait, wait);
- if (atomic_read(&sfp->waiting) > 0)
+ num = atomic_read(&sfp->waiting);
+ if (num < 1) {
+ poll_wait(filp, &sfp->read_wait, wait);
+ num = atomic_read(&sfp->waiting);
+ }
+ if (num > 0)
p_res = EPOLLIN | EPOLLRDNORM;

if (unlikely(SG_IS_DETACHING(sfp->parentdp)))
@@ -2344,7 +2376,7 @@ sg_check_sense(struct sg_device *sdp, struct sg_request *srp, int sense_len)
{
int driver_stat;
u32 rq_res = srp->rq_result;
- struct scsi_cmnd *scmd = blk_mq_rq_to_pdu(srp->rq);
+ struct scsi_cmnd *scmd = blk_mq_rq_to_pdu(READ_ONCE(srp->rqq));
u8 *sbp = scmd ? scmd->sense_buffer : NULL;

if (!sbp)
@@ -2379,32 +2411,18 @@ sg_check_sense(struct sg_device *sdp, struct sg_request *srp, int sense_len)
* (sync) usage, sg_ctl_sg_io() waits to be woken up by this callback.
*/
static void
-sg_rq_end_io(struct request *rq, blk_status_t status)
+sg_rq_end_io(struct request *rqq, blk_status_t status)
{
enum sg_rq_state rqq_state = SG_RS_AWAIT_RCV;
int a_resid, slen;
- struct scsi_cmnd *scmd = blk_mq_rq_to_pdu(rq);
- struct sg_request *srp = rq->end_io_data;
+ unsigned long iflags;
+ struct scsi_cmnd *scmd = blk_mq_rq_to_pdu(rqq);
+ struct sg_request *srp = rqq->end_io_data;
struct sg_device *sdp;
struct sg_fd *sfp;

- if (!srp) {
- WARN_ONCE("%s: srp unexpectedly NULL\n", __func__);
- return;
- }
- if (WARN_ON(atomic_read(&srp->rq_st) != SG_RS_INFLIGHT)) {
- pr_warn("%s: bad rq_st=%d\n", __func__,
- atomic_read(&srp->rq_st));
- goto early_err;
- }
sfp = srp->parentfp;
- if (unlikely(!sfp)) {
- WARN_ONCE(1, "%s: sfp unexpectedly NULL", __func__);
- goto early_err;
- }
sdp = sfp->parentdp;
- if (unlikely(SG_IS_DETACHING(sdp)))
- pr_info("%s: device detaching\n", __func__);

srp->rq_result = scmd->result;
slen = min_t(int, scmd->sense_len, SCSI_SENSE_BUFFERSIZE);
@@ -2412,7 +2430,7 @@ sg_rq_end_io(struct request *rq, blk_status_t status)

if (a_resid) {
if (test_bit(SG_FRQ_IS_V4I, srp->frq_bm)) {
- if (rq_data_dir(rq) == READ)
+ if (rq_data_dir(rqq) == READ)
srp->in_resid = a_resid;
else
srp->s_hdr4.out_resid = a_resid;
@@ -2456,16 +2474,29 @@ sg_rq_end_io(struct request *rq, blk_status_t status)
set_bit(SG_FRQ_DEACT_ORPHAN, srp->frq_bm);
}
}
- if (!test_bit(SG_FRQ_SYNC_INVOC, srp->frq_bm))
- atomic_inc(&sfp->waiting);
- if (unlikely(sg_rq_state_chg(srp, SG_RS_INFLIGHT, rqq_state)))
- pr_warn("%s: can't set rq_st\n", __func__);
+ xa_lock_irqsave(&sfp->srp_arr, iflags);
+ sg_rq_chg_state_force_ulck(srp, rqq_state);
+ WRITE_ONCE(srp->rqq, NULL);
+ if (test_bit(SG_FRQ_COUNT_ACTIVE, srp->frq_bm)) {
+ int num = atomic_inc_return(&sfp->waiting);
+
+ if (num < 2) {
+ WRITE_ONCE(sfp->low_await_idx, srp->rq_idx);
+ } else {
+ int l_await_idx = READ_ONCE(sfp->low_await_idx);
+
+ if (l_await_idx < 0 || srp->rq_idx < l_await_idx ||
+ !xa_get_mark(&sfp->srp_arr, l_await_idx, SG_XA_RQ_AWAIT))
+ WRITE_ONCE(sfp->low_await_idx, srp->rq_idx);
+ }
+ }
+ xa_unlock_irqrestore(&sfp->srp_arr, iflags);
+
/*
* Free the mid-level resources apart from the bio (if any). The bio's
* blk_rq_unmap_user() can be called later from user context.
*/
- srp->rq = NULL;
- blk_mq_free_request(rq);
+ blk_mq_free_request(rqq);

if (likely(rqq_state == SG_RS_AWAIT_RCV)) {
/* Wake any sg_read()/ioctl(SG_IORECEIVE) awaiting this req */
@@ -2477,10 +2508,6 @@ sg_rq_end_io(struct request *rq, blk_status_t status)
schedule_work(&srp->ew_orph.work);
}
return;
-
-early_err:
- srp->rq = NULL;
- blk_mq_free_request(rq);
}

static const struct file_operations sg_fops = {
@@ -2815,7 +2842,7 @@ sg_start_req(struct sg_request *srp, struct sg_comm_wr_t *cwrp, int dxfer_dir)
u32 rq_flags = srp->rq_flags;
unsigned int iov_count = 0;
void __user *up;
- struct request *rq;
+ struct request *rqq;
struct scsi_cmnd *scmd;
struct sg_fd *sfp = cwrp->sfp;
struct sg_device *sdp;
@@ -2864,12 +2891,12 @@ sg_start_req(struct sg_request *srp, struct sg_comm_wr_t *cwrp, int dxfer_dir)
* do not want to use BLK_MQ_REQ_NOWAIT here because userspace might
* not expect an EWOULDBLOCK from this condition.
*/
- rq = scsi_alloc_request(q, (r0w ? REQ_OP_DRV_OUT : REQ_OP_DRV_IN), 0);
- if (IS_ERR(rq))
- return PTR_ERR(rq);
+ rqq = scsi_alloc_request(q, (r0w ? REQ_OP_DRV_OUT : REQ_OP_DRV_IN), 0);
+ if (IS_ERR(rqq))
+ return PTR_ERR(rqq);
/* current sg_request protected by SG_RS_BUSY state */
- scmd = blk_mq_rq_to_pdu(rq);
- srp->rq = rq;
+ scmd = blk_mq_rq_to_pdu(rqq);
+ WRITE_ONCE(srp->rqq, rqq);

if (cwrp->u_cmdp)
res = sg_fetch_cmnd(cwrp->filp, sfp, cwrp->u_cmdp,
@@ -2883,7 +2910,7 @@ sg_start_req(struct sg_request *srp, struct sg_comm_wr_t *cwrp, int dxfer_dir)
us_xfer = !(rq_flags & (SG_FLAG_NO_DXFER | SG_FLAG_MMAP_IO));
assign_bit(SG_FRQ_NO_US_XFER, srp->frq_bm, !us_xfer);
reserved = (sfp->rsv_srp == srp);
- rq->end_io_data = srp;
+ rqq->end_io_data = srp;
scmd->retries = SG_DEFAULT_RETRIES;
req_schp = &srp->sgat_h;

@@ -2934,24 +2961,24 @@ sg_start_req(struct sg_request *srp, struct sg_comm_wr_t *cwrp, int dxfer_dir)
}

if (us_xfer)
- res = blk_rq_map_user_iov(q, rq, md, &i, GFP_ATOMIC);
+ res = blk_rq_map_user_iov(q, rqq, md, &i, GFP_ATOMIC);
kfree(iov);
if (IS_ENABLED(CONFIG_SCSI_PROC_FS))
cp = "iov_count > 0";
} else if (us_xfer) { /* setup for transfer data to/from user space */
- res = blk_rq_map_user(q, rq, md, up, dxfer_len, GFP_ATOMIC);
+ res = blk_rq_map_user(q, rqq, md, up, dxfer_len, GFP_ATOMIC);
if (IS_ENABLED(CONFIG_SCSI_PROC_FS) && res)
SG_LOG(1, sfp, "%s: blk_rq_map_user() res=%d\n",
__func__, res);
}
fini:
if (unlikely(res)) { /* failure, free up resources */
- srp->rq = NULL;
- if (us_xfer && rq->bio)
- blk_rq_unmap_user(rq->bio);
- blk_mq_free_request(rq);
+ WRITE_ONCE(srp->rqq, NULL);
+ if (us_xfer && rqq->bio)
+ blk_rq_unmap_user(rqq->bio);
+ blk_mq_free_request(rqq);
} else {
- srp->bio = rq->bio;
+ srp->bio = rqq->bio;
}
SG_LOG((res ? 1 : 4), sfp, "%s: %s res=%d [0x%pK]\n", __func__, cp,
res, srp);
@@ -2970,19 +2997,19 @@ sg_finish_scsi_blk_rq(struct sg_request *srp)
{
int ret;
struct sg_fd *sfp = srp->parentfp;
- struct request *rq = srp->rq;
+ struct request *rqq = READ_ONCE(srp->rqq);

SG_LOG(4, sfp, "%s: srp=0x%pK%s\n", __func__, srp,
(srp->parentfp->rsv_srp == srp) ? " rsv" : "");
- if (!test_bit(SG_FRQ_SYNC_INVOC, srp->frq_bm)) {
+ if (test_and_clear_bit(SG_FRQ_COUNT_ACTIVE, srp->frq_bm)) {
atomic_dec(&sfp->submitted);
atomic_dec(&sfp->waiting);
}

- /* Expect blk_mq_free_request(rq) already called in sg_rq_end_io() */
- if (rq) { /* blk_get_request() may have failed */
- srp->rq = NULL;
- blk_mq_free_request(rq);
+ /* Expect blk_mq_free_request(rqq) already called in sg_rq_end_io() */
+ if (rqq) { /* scsi_alloc_request() may have failed */
+ WRITE_ONCE(srp->rqq, NULL);
+ blk_mq_free_request(rqq);
}
if (srp->bio) {
bool us_xfer = !test_bit(SG_FRQ_NO_US_XFER, srp->frq_bm);
@@ -3159,19 +3186,30 @@ sg_find_srp_by_id(struct sg_fd *sfp, int pack_id)
bool second = false;
int res;
int num_waiting = atomic_read(&sfp->waiting);
- unsigned long idx, start_idx, end_idx;
+ int l_await_idx = READ_ONCE(sfp->low_await_idx);
+ unsigned long idx, s_idx;
+ unsigned long end_idx = ULONG_MAX;
struct sg_request *srp = NULL;
struct xarray *xafp = &sfp->srp_arr;

- if (num_waiting < 1)
- return NULL;
+ if (num_waiting < 1) {
+ num_waiting = atomic_read_acquire(&sfp->waiting);
+ if (num_waiting < 1)
+ return NULL;
+ }
+
+ s_idx = (l_await_idx < 0) ? 0 : l_await_idx;
+ idx = s_idx;
if (unlikely(search_for_1)) {
- xa_for_each_marked(xafp, idx, srp, SG_XA_RQ_AWAIT) {
+second_time:
+ for (srp = xa_find(xafp, &idx, end_idx, SG_XA_RQ_AWAIT);
+ srp;
+ srp = xa_find_after(xafp, &idx, end_idx, SG_XA_RQ_AWAIT)) {
if (test_bit(SG_FRQ_SYNC_INVOC, srp->frq_bm))
continue;
if (srp->pack_id != pack_id)
continue;
- res = sg_rq_state_chg(srp, SG_RS_AWAIT_RCV, SG_RS_BUSY);
+ res = sg_rq_chg_state(srp, SG_RS_AWAIT_RCV, SG_RS_BUSY);
if (likely(res == 0))
goto good;
/* else another caller got it, move on */
@@ -3181,6 +3219,14 @@ sg_find_srp_by_id(struct sg_fd *sfp, int pack_id)
}
break;
}
+ /* If not found so far, need to wrap around and search [0 ... s_idx) */
+ if (!srp && !second && s_idx > 0) {
+ end_idx = s_idx - 1;
+ s_idx = 0;
+ idx = s_idx;
+ second = true;
+ goto second_time;
+ }
} else {
/*
* Searching for _any_ request is the more likely usage. Start searching with the
@@ -3189,29 +3235,27 @@ sg_find_srp_by_id(struct sg_fd *sfp, int pack_id)
* is ready. If there is no queuing and the "last used" has been re-used then the
* first (relative) position will be the request we want.
*/
- start_idx = READ_ONCE(sfp->prev_used_idx);
- end_idx = ULONG_MAX;
-second_time:
- idx = start_idx;
+second_time2:
for (srp = xa_find(xafp, &idx, end_idx, SG_XA_RQ_AWAIT);
srp;
srp = xa_find_after(xafp, &idx, end_idx, SG_XA_RQ_AWAIT)) {
if (test_bit(SG_FRQ_SYNC_INVOC, srp->frq_bm))
continue;
- res = sg_rq_state_chg(srp, SG_RS_AWAIT_RCV, SG_RS_BUSY);
- if (likely(res == 0))
+ res = sg_rq_chg_state(srp, SG_RS_AWAIT_RCV, SG_RS_BUSY);
+ if (likely(res == 0)) {
+ WRITE_ONCE(sfp->low_await_idx, idx + 1);
goto good;
+ }
#if IS_ENABLED(SG_LOG_ACTIVE)
- else
- sg_rq_state_fail_msg(sfp, SG_RS_AWAIT_RCV, SG_RS_BUSY, __func__);
+ sg_rq_state_fail_msg(sfp, SG_RS_AWAIT_RCV, SG_RS_BUSY, __func__);
#endif
}
- /* If not found so far, need to wrap around and search [0 ... start_idx) */
- if (!srp && !second && start_idx > 0) {
- end_idx = start_idx - 1;
- start_idx = 0;
+ if (!srp && !second && s_idx > 0) {
+ end_idx = s_idx - 1;
+ s_idx = 0;
+ idx = s_idx;
second = true;
- goto second_time;
+ goto second_time2;
}
}
/* here if one of above loops does _not_ find a match */
@@ -3330,11 +3374,12 @@ sg_setup_req(struct sg_comm_wr_t *cwrp, int dxfr_len)
bool mk_new_srp = true;
bool try_harder = false;
bool second = false;
- int num_inactive = 0;
- unsigned long idx, start_idx, end_idx, iflags;
+ bool has_inactive = false;
+ int l_used_idx;
+ unsigned long idx, s_idx, end_idx, iflags;
struct sg_fd *fp = cwrp->sfp;
struct sg_request *r_srp = NULL; /* request to return */
- struct sg_request *last_srp = NULL;
+ struct sg_request *low_srp = NULL;
struct xarray *xafp = &fp->srp_arr;
__maybe_unused const char *cp;

@@ -3343,49 +3388,70 @@ sg_setup_req(struct sg_comm_wr_t *cwrp, int dxfr_len)
if (xa_empty(xafp)) {
act_empty = true;
mk_new_srp = true;
+ } else if (atomic_read(&fp->inactives) <= 0) {
+ mk_new_srp = true;
} else if (!try_harder && dxfr_len < SG_DEF_SECTOR_SZ) {
+ l_used_idx = READ_ONCE(fp->low_used_idx);
+ s_idx = (l_used_idx < 0) ? 0 : l_used_idx;
+ if (l_used_idx >= 0 && xa_get_mark(xafp, s_idx, SG_XA_RQ_INACTIVE)) {
+ r_srp = xa_load(xafp, s_idx);
+ if (r_srp && r_srp->sgat_h.buflen <= SG_DEF_SECTOR_SZ) {
+ if (sg_rq_chg_state(r_srp, SG_RS_INACTIVE, SG_RS_BUSY) == 0) {
+ found = true;
+ atomic_dec(&fp->inactives);
+ goto have_existing;
+ }
+ }
+ }
xa_for_each_marked(xafp, idx, r_srp, SG_XA_RQ_INACTIVE) {
- ++num_inactive;
- if (dxfr_len < SG_DEF_SECTOR_SZ)
- last_srp = r_srp;
+ has_inactive = true;
+ if (!low_srp && dxfr_len < SG_DEF_SECTOR_SZ) {
+ low_srp = r_srp;
+ break;
+ }
}
- /* If dxfr_len is small, use last inactive request */
- if (last_srp) {
- r_srp = last_srp;
- if (sg_rq_state_chg(r_srp, SG_RS_INACTIVE, SG_RS_BUSY))
+ /* If dxfr_len is small, use lowest inactive request */
+ if (low_srp) {
+ r_srp = low_srp;
+ if (sg_rq_chg_state(r_srp, SG_RS_INACTIVE, SG_RS_BUSY))
goto start_again; /* gone to another thread */
+ atomic_dec(&fp->inactives);
cp = "toward end of srp_arr";
found = true;
}
} else {
- start_idx = READ_ONCE(fp->prev_used_idx);
+ l_used_idx = READ_ONCE(fp->low_used_idx);
+ s_idx = (l_used_idx < 0) ? 0 : l_used_idx;
+ idx = s_idx;
end_idx = ULONG_MAX;
second_time:
- idx = start_idx;
for (r_srp = xa_find(xafp, &idx, end_idx, SG_XA_RQ_INACTIVE);
r_srp;
r_srp = xa_find_after(xafp, &idx, end_idx, SG_XA_RQ_INACTIVE)) {
if (r_srp->sgat_h.buflen >= dxfr_len) {
- if (sg_rq_state_chg(r_srp, SG_RS_INACTIVE, SG_RS_BUSY))
+ if (sg_rq_chg_state(r_srp, SG_RS_INACTIVE, SG_RS_BUSY))
continue;
+ atomic_dec(&fp->inactives);
+ WRITE_ONCE(fp->low_used_idx, idx + 1);
cp = "near front of srp_arr";
found = true;
break;
}
}
/* If not found so far, need to wrap around and search [0 ... start_idx) */
- if (!r_srp && !second && start_idx > 0) {
- end_idx = start_idx - 1;
- start_idx = 0;
+ if (!r_srp && !second && s_idx > 0) {
+ end_idx = s_idx - 1;
+ s_idx = 0;
+ idx = s_idx;
second = true;
goto second_time;
}
}
+have_existing:
if (found) {
r_srp->in_resid = 0;
r_srp->rq_info = 0;
r_srp->sense_len = 0;
- WRITE_ONCE(fp->prev_used_idx, r_srp->rq_idx);
mk_new_srp = false;
} else {
mk_new_srp = true;
@@ -3394,7 +3460,6 @@ sg_setup_req(struct sg_comm_wr_t *cwrp, int dxfr_len)
bool allow_cmd_q = test_bit(SG_FFD_CMD_Q, fp->ffd_bm);
int res;
u32 n_idx;
- struct xa_limit xal = { .max = 0, .min = 0 };

cp = "new";
if (!allow_cmd_q && atomic_read(&fp->submitted) > 0) {
@@ -3406,16 +3471,14 @@ sg_setup_req(struct sg_comm_wr_t *cwrp, int dxfr_len)
r_srp = sg_mk_srp_sgat(fp, act_empty, dxfr_len);
if (IS_ERR(r_srp)) {
if (!try_harder && dxfr_len < SG_DEF_SECTOR_SZ &&
- num_inactive > 0) {
+ has_inactive) {
try_harder = true;
goto start_again;
}
goto fini;
}
- atomic_set(&r_srp->rq_st, SG_RS_BUSY);
xa_lock_irqsave(xafp, iflags);
- xal.max = atomic_inc_return(&fp->req_cnt);
- res = __xa_alloc(xafp, &n_idx, r_srp, xal, GFP_KERNEL);
+ res = __xa_alloc(xafp, &n_idx, r_srp, xa_limit_32b, GFP_KERNEL);
xa_unlock_irqrestore(xafp, iflags);
if (res < 0) {
SG_LOG(1, fp, "%s: xa_alloc() failed, errno=%d\n",
@@ -3458,7 +3521,8 @@ sg_deact_request(struct sg_fd *sfp, struct sg_request *srp)
sbp = srp->sense_bp;
srp->sense_bp = NULL;
WRITE_ONCE(srp->frq_bm[0], 0);
- sg_rq_state_chg_force(srp, SG_RS_INACTIVE);
+ sg_rq_chg_state_force(srp, SG_RS_INACTIVE);
+ atomic_inc(&sfp->inactives);
/* maybe orphaned req, thus never read */
if (sbp)
mempool_free(sbp, sg_sense_pool);
@@ -3477,7 +3541,6 @@ sg_add_sfp(struct sg_device *sdp)
struct sg_request *srp = NULL;
struct xarray *xadp = &sdp->sfp_arr;
struct xarray *xafp;
- struct xa_limit xal;

sfp = kzalloc(sizeof(*sfp), GFP_ATOMIC | __GFP_NOWARN);
if (!sfp)
@@ -3494,8 +3557,6 @@ sg_add_sfp(struct sg_device *sdp)
__assign_bit(SG_FFD_CMD_Q, sfp->ffd_bm, SG_DEF_COMMAND_Q);
__assign_bit(SG_FFD_KEEP_ORPHAN, sfp->ffd_bm, SG_DEF_KEEP_ORPHAN);
__assign_bit(SG_FFD_Q_AT_TAIL, sfp->ffd_bm, SG_DEFAULT_Q_AT);
- atomic_set(&sfp->submitted, 0);
- atomic_set(&sfp->waiting, 0);
/*
* SG_SCATTER_SZ initializes scatter_elem_sz but different value may
* be given as driver/module parameter (e.g. 'scatter_elem_sz=8192').
@@ -3507,7 +3568,7 @@ sg_add_sfp(struct sg_device *sdp)
sfp->parentdp = sdp;
atomic_set(&sfp->submitted, 0);
atomic_set(&sfp->waiting, 0);
- atomic_set(&sfp->req_cnt, 0);
+ atomic_set(&sfp->inactives, 0);

if (unlikely(SG_IS_DETACHING(sdp))) {
SG_LOG(1, sfp, "%s: detaching\n", __func__);
@@ -3519,8 +3580,6 @@ sg_add_sfp(struct sg_device *sdp)

rbuf_len = min_t(int, sg_big_buff, sdp->max_sgat_sz);
if (rbuf_len > 0) {
- struct xa_limit xalrq = { .max = 0, .min = 0 };
-
srp = sg_build_reserve(sfp, rbuf_len);
if (IS_ERR(srp)) {
err = PTR_ERR(srp);
@@ -3536,8 +3595,7 @@ sg_add_sfp(struct sg_device *sdp)
__func__, rbuf_len, srp->sgat_h.buflen);
}
xa_lock_irqsave(xafp, iflags);
- xalrq.max = atomic_inc_return(&sfp->req_cnt);
- res = __xa_alloc(xafp, &idx, srp, xalrq, GFP_ATOMIC);
+ res = __xa_alloc(xafp, &idx, srp, xa_limit_32b, GFP_ATOMIC);
xa_unlock_irqrestore(xafp, iflags);
if (res < 0) {
SG_LOG(1, sfp, "%s: xa_alloc(srp) bad, errno=%d\n",
@@ -3549,20 +3607,19 @@ sg_add_sfp(struct sg_device *sdp)
}
srp->rq_idx = idx;
srp->parentfp = sfp;
- sg_rq_state_chg_force(srp, SG_RS_INACTIVE);
+ sg_rq_chg_state_force(srp, SG_RS_INACTIVE);
+ atomic_inc(&sfp->inactives);
}
if (!reduced) {
SG_LOG(4, sfp, "%s: built reserve buflen=%d\n", __func__,
rbuf_len);
}
xa_lock_irqsave(xadp, iflags);
- xal.min = 0;
- xal.max = atomic_read(&sdp->open_cnt);
- res = __xa_alloc(xadp, &idx, sfp, xal, GFP_KERNEL);
+ res = __xa_alloc(xadp, &idx, sfp, xa_limit_32b, GFP_KERNEL);
xa_unlock_irqrestore(xadp, iflags);
if (res < 0) {
pr_warn("%s: xa_alloc(sdp) bad, o_count=%d, errno=%d\n",
- __func__, xal.max, -res);
+ __func__, atomic_read(&sdp->open_cnt), -res);
if (srp) {
sg_remove_sgat(srp);
kfree(srp);
@@ -3974,12 +4031,13 @@ sg_proc_debug_fd(struct sg_fd *fp, char *obp, int len, unsigned long idx)
(int)test_bit(SG_FFD_FORCE_PACKID, fp->ffd_bm),
(int)test_bit(SG_FFD_KEEP_ORPHAN, fp->ffd_bm),
fp->ffd_bm[0]);
- n += scnprintf(obp + n, len - n, " mmap_sz=%d prev_used_idx=%d\n",
- fp->mmap_sz, fp->prev_used_idx);
n += scnprintf(obp + n, len - n,
- " submitted=%d waiting=%d open thr_id=%d\n",
+ " mmap_sz=%d low_used_idx=%d low_await_idx=%d\n",
+ fp->mmap_sz, READ_ONCE(fp->low_used_idx), READ_ONCE(fp->low_await_idx));
+ n += scnprintf(obp + n, len - n,
+ " submitted=%d waiting=%d inactives=%d open thr_id=%d\n",
atomic_read(&fp->submitted),
- atomic_read(&fp->waiting), fp->tid);
+ atomic_read(&fp->waiting), atomic_read(&fp->inactives), fp->tid);
k = 0;
xa_lock_irqsave(&fp->srp_arr, iflags);
xa_for_each(&fp->srp_arr, idx, srp) {
--
2.25.1