[PATCH v16 41/45] sg: track lowest inactive and await indexes

Douglas Gilbert
2021-02-20T02:07:42Z

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.

Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Douglas Gilbert <dgilbert@interlog.com>
---
drivers/scsi/sg.c | 304 ++++++++++++++++++++++++++--------------------
1 file changed, 175 insertions(+), 129 deletions(-)

diff --git a/drivers/scsi/sg.c b/drivers/scsi/sg.c
index 862a7c158e4e..5f8c4fe38ce6 100644
--- a/drivers/scsi/sg.c
+++ b/drivers/scsi/sg.c
@@ -116,6 +116,7 @@ enum sg_rq_state { /* N.B. sg_rq_state_arr assumes SG_RS_AWAIT_RCV==2 */
#define SG_FRQ_RECEIVING 7 /* guard against multiple receivers */
#define SG_FRQ_BLK_PUT_REQ 8 /* set when blk_put_request() called */
#define SG_FRQ_FOR_MMAP 9 /* request needs PAGE_SIZE elements */
+#define SG_FRQ_COUNT_ACTIVE 10 /* 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 */
@@ -225,11 +226,12 @@ 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);
}

@@ -1007,11 +1025,13 @@ 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);
+ set_bit(SG_FRQ_COUNT_ACTIVE, srp->frq_bm);
+ }
blk_execute_rq_nowait(sdp->device->request_queue, sdp->disk,
srp->rq, (int)at_head, sg_rq_end_io);
}
@@ -1666,7 +1686,7 @@ 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));
}

@@ -1682,6 +1702,8 @@ 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,
@@ -1694,14 +1716,16 @@ 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__);
@@ -1797,7 +1821,6 @@ sg_set_reserved_sz(struct sg_fd *sfp, int want_rsv_sz)
n_srp = sg_mk_srp_sgat(sfp, true /* can take time */, new_sz);
if (IS_ERR(n_srp))
return PTR_ERR(n_srp);
- sg_rq_state_force(n_srp, SG_RS_INACTIVE);
/* new sg_request object, sized correctly is now available */
try_again:
o_srp = sfp->rsv_srp;
@@ -1828,7 +1851,8 @@ sg_set_reserved_sz(struct sg_fd *sfp, int want_rsv_sz)
cxc_srp = __xa_cmpxchg(xafp, idx, o_srp, n_srp, GFP_ATOMIC);
if (o_srp == cxc_srp) {
sfp->rsv_srp = n_srp;
- sg_rq_state_force(n_srp, SG_RS_INACTIVE);
+ sg_rq_chg_state_force_ulck(n_srp, SG_RS_INACTIVE);
+ /* don't bump inactives, since replaced an inactive */
xa_unlock_irqrestore(xafp, iflags);
SG_LOG(6, sfp, "%s: new rsv srp=0x%pK ++\n", __func__,
n_srp);
@@ -2006,7 +2030,10 @@ 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);
@@ -2219,11 +2246,16 @@ sg_compat_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)))
@@ -2471,32 +2503,13 @@ sg_rq_end_io(struct request *rq, blk_status_t status)
struct sg_device *sdp;
struct sg_fd *sfp;

- if (!scsi_rp) {
- WARN_ONCE("%s: scsi_req(rq) unexpectedly NULL\n", __func__);
- return;
- }
- if (!srp) {
- WARN_ONCE("%s: srp unexpectedly NULL\n", __func__);
- return;
- }
/* Expect 0 --> 1 transition, otherwise processed elsewhere */
if (unlikely(test_and_set_bit(SG_FRQ_BLK_PUT_REQ, srp->frq_bm))) {
pr_info("%s: srp=%pK already completed\n", __func__, srp);
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 = scsi_rp->result;
slen = min_t(int, scsi_rp->sense_len, SCSI_SENSE_BUFFERSIZE);
@@ -2549,10 +2562,20 @@ 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__);
+ 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);
+ }
+ }
+ sg_rq_chg_state_force(srp, rqq_state);
/*
* 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.
@@ -2571,12 +2594,6 @@ sg_rq_end_io(struct request *rq, blk_status_t status)
schedule_work(&srp->ew_orph.work);
}
return;
-
-early_err:
- srp->rq = NULL;
- if (scsi_rp)
- scsi_req_free_cmd(scsi_rp);
- blk_put_request(rq);
}

static const struct file_operations sg_fops = {
@@ -3065,7 +3082,7 @@ sg_finish_scsi_blk_rq(struct sg_request *srp)

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);
}
@@ -3261,19 +3278,28 @@ 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) {
- if (!srp)
- continue;
+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 (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 */
@@ -3283,6 +3309,14 @@ 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
@@ -3291,27 +3325,25 @@ 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)) {
- 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 */
@@ -3430,11 +3462,12 @@ 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;

@@ -3443,49 +3476,70 @@ 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;
@@ -3494,7 +3548,6 @@ 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) {
@@ -3506,16 +3559,14 @@ 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",
@@ -3558,7 +3609,8 @@ 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);
@@ -3577,7 +3629,6 @@ 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)
@@ -3594,8 +3645,6 @@ 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').
@@ -3607,7 +3656,7 @@ 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__);
@@ -3619,8 +3668,6 @@ 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)) {
kfree(sfp);
@@ -3636,8 +3683,7 @@ 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",
@@ -3649,20 +3695,19 @@ 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);
@@ -4076,12 +4121,13 @@ 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