Various renamings and reductions of atomic operations:
- rename mrq control object pointer from cv4p to mrqcp
- change sense of internal file descriptor bitop
SG_FFD_CMD_Q, now SG_FFD_NO_CMD_Q
- add early exit to sg_find_srp_by_id() if waiting
atomic < 1
- change some atomic bitops into non-atomic variant
Signed-off-by: Douglas Gilbert <dgilbert@xxxxxxxxxxxx>
---
drivers/scsi/sg.c | 100 ++++++++++++++++++++++++----------------------
1 file changed, 53 insertions(+), 47 deletions(-)
diff --git a/drivers/scsi/sg.c b/drivers/scsi/sg.c
index 3d659ff90788..4ccb7ab469f1 100644
--- a/drivers/scsi/sg.c
+++ b/drivers/scsi/sg.c
@@ -142,7 +142,7 @@ enum sg_shr_var {
/* Bit positions (flags) for sg_fd::ffd_bm bitmask follow */
#define SG_FFD_FORCE_PACKID 0 /* receive only given pack_id/tag */
-#define SG_FFD_CMD_Q 1 /* clear: only 1 active req per fd */
+#define SG_FFD_NO_CMD_Q 1 /* set: only 1 active req per fd */
#define SG_FFD_KEEP_ORPHAN 2 /* policy for this fd */
#define SG_FFD_HIPRI_SEEN 3 /* could have HIPRI requests active */
#define SG_FFD_TIME_IN_NS 4 /* set: time in nanoseconds, else ms */
@@ -882,8 +882,9 @@ sg_submit_v3(struct sg_fd *sfp, struct sg_io_hdr *hp, bool sync,
if (unlikely(res))
return res;
}
- /* when v3 seen, allow cmd_q on this fd (def: no cmd_q) */
- set_bit(SG_FFD_CMD_Q, sfp->ffd_bm);
+ /* when v3 seen, allow cmd_q on this fd (def: cmd_q) */
+ if (test_bit(SG_FFD_NO_CMD_Q, sfp->ffd_bm))
+ clear_bit(SG_FFD_NO_CMD_Q, sfp->ffd_bm);
ul_timeout = msecs_to_jiffies(hp->timeout);
WRITE_ONCE(cwr.frq_bm[0], 0);
__assign_bit(SG_FRQ_SYNC_INVOC, cwr.frq_bm, (int)sync);
@@ -904,17 +905,10 @@ sg_submit_v3(struct sg_fd *sfp, struct sg_io_hdr *hp, bool sync,
static void
sg_sgv4_out_zero(struct sg_io_v4 *h4p)
{
- h4p->driver_status = 0;
- h4p->transport_status = 0;
- h4p->device_status = 0;
- h4p->retry_delay = 0;
- h4p->info = 0;
- h4p->response_len = 0;
- h4p->duration = 0;
- h4p->din_resid = 0;
- h4p->dout_resid = 0;
- h4p->generated_tag = 0;
- h4p->spare_out = 0;
+ const int off = offsetof(struct sg_io_v4, driver_status);
+
+ /* clear from and including driver_status to end of object */
+ memset((u8 *)h4p + off, 0, SZ_SG_IO_V4 - off);
}
/*
@@ -984,7 +978,7 @@ sg_mrq_complets(struct sg_io_v4 *cop, struct sg_io_v4 *a_hds,
SG_LOG(3, sfp, "%s: mreqs=%d, sec_reqs=%d\n", __func__, mreqs,
sec_reqs);
- for ( ; sum_inflight > 0; --sum_inflight) {
+ for ( ; sum_inflight > 0; --sum_inflight, ++cop->info) {
srp = NULL;
if (mreqs > 0 && sg_mrq_get_ready_srp(sfp, &srp)) {
if (IS_ERR(srp)) { /* -ENODATA: no mrqs here */
@@ -1248,13 +1242,17 @@ sg_do_multi_req(struct sg_comm_wr_t *cwrp, bool blocking)
rq_sfp = o_sfp;
if (!set_other) {
set_other = true;
- set_bit(SG_FFD_CMD_Q, rq_sfp->ffd_bm);
+ if (test_bit(SG_FFD_NO_CMD_Q, rq_sfp->ffd_bm))
+ clear_bit(SG_FFD_NO_CMD_Q,
+ rq_sfp->ffd_bm);
}
} else {
rq_sfp = fp;
if (!set_this) {
set_this = true;
- set_bit(SG_FFD_CMD_Q, rq_sfp->ffd_bm);
+ if (test_bit(SG_FFD_NO_CMD_Q, rq_sfp->ffd_bm))
+ clear_bit(SG_FFD_NO_CMD_Q,
+ rq_sfp->ffd_bm);
}
}
if (cdb_ap) { /* already have array of cdbs */
@@ -1380,7 +1378,8 @@ sg_submit_v4(struct sg_fd *sfp, void __user *p, struct sg_io_v4 *h4p,
return res;
}
/* once v4 (or v3) seen, allow cmd_q on this fd (def: no cmd_q) */
- set_bit(SG_FFD_CMD_Q, sfp->ffd_bm);
+ if (test_bit(SG_FFD_NO_CMD_Q, sfp->ffd_bm))
+ clear_bit(SG_FFD_NO_CMD_Q, sfp->ffd_bm);
ul_timeout = msecs_to_jiffies(h4p->timeout);
cwr.sfp = sfp;
WRITE_ONCE(cwr.frq_bm[0], 0);
@@ -1728,14 +1727,14 @@ sg_common_write(struct sg_comm_wr_t *cwrp)
pack_id = hi_p->pack_id;
}
if (unlikely(rq_flags & SGV4_FLAG_MULTIPLE_REQS))
- return ERR_PTR(-ERANGE);
+ return ERR_PTR(-ERANGE); /* only control object sets this */
if (sg_fd_is_shared(fp)) {
res = sg_share_chk_flags(fp, rq_flags, dxfr_len, dir, &sh_var);
if (unlikely(res < 0))
return ERR_PTR(res);
} else {
sh_var = SG_SHR_NONE;
- if (rq_flags & SGV4_FLAG_SHARE)
+ if (unlikely(rq_flags & SGV4_FLAG_SHARE))
return ERR_PTR(-ENOMSG);
}
if (unlikely(dxfr_len >= SZ_256M))
@@ -2828,17 +2827,14 @@ sg_rq_landed(struct sg_device *sdp, struct sg_request *srp)
return atomic_read_acquire(&srp->rq_st) != SG_RQ_INFLIGHT || SG_IS_DETACHING(sdp);
}
-/*
- * This is a blocking wait for a specific srp. When h4p is non-NULL, it is
- * the blocking multiple request case
- */
+/* This is a blocking wait then complete for a specific srp. */
static int
sg_wait_event_srp(struct sg_fd *sfp, void __user *p, struct sg_io_v4 *h4p,
struct sg_request *srp)
{
int res;
- enum sg_rq_state sr_st;
struct sg_device *sdp = sfp->parentdp;
+ enum sg_rq_state sr_st;
if (atomic_read(&srp->rq_st) != SG_RQ_INFLIGHT)
goto skip_wait; /* and skip _acquire() */
@@ -2993,8 +2989,10 @@ sg_match_first_mrq_after(struct sg_fd *sfp, int pack_id,
unsigned long idx;
struct sg_request *srp;
- if (atomic_read(&sfp->waiting) < 1)
- return NULL;
+ if (atomic_read(&sfp->waiting) < 1) {
+ if (atomic_read_acquire(&sfp->waiting) < 1)
+ return NULL;
+ }
once_more:
xa_for_each_marked(&sfp->srp_arr, idx, srp, SG_XA_RQ_AWAIT) {
if (unlikely(!srp))
@@ -4170,16 +4168,16 @@ sg_ioctl_common(struct file *filp, struct sg_device *sdp, struct sg_fd *sfp,
val);
res = put_user(val, ip);
return res;
- case SG_SET_COMMAND_Q:
+ case SG_SET_COMMAND_Q: /* set by driver whenever v3 or v4 req seen */
SG_LOG(3, sfp, "%s: SG_SET_COMMAND_Q\n", __func__);
res = get_user(val, ip);
if (unlikely(res))
return res;
- assign_bit(SG_FFD_CMD_Q, sfp->ffd_bm, !!val);
+ assign_bit(SG_FFD_NO_CMD_Q, sfp->ffd_bm, !val);
return 0;
case SG_GET_COMMAND_Q:
SG_LOG(3, sfp, "%s: SG_GET_COMMAND_Q\n", __func__);
- return put_user(test_bit(SG_FFD_CMD_Q, sfp->ffd_bm), ip);
+ return put_user(!test_bit(SG_FFD_NO_CMD_Q, sfp->ffd_bm), ip);
case SG_SET_KEEP_ORPHAN:
SG_LOG(3, sfp, "%s: SG_SET_KEEP_ORPHAN\n", __func__);
res = get_user(val, ip);
@@ -4436,7 +4434,7 @@ sg_poll(struct file *filp, poll_table *wait)
if (SG_IS_DETACHING(sfp->parentdp))
p_res |= EPOLLHUP;
- else if (likely(test_bit(SG_FFD_CMD_Q, sfp->ffd_bm)))
+ else if (likely(!test_bit(SG_FFD_NO_CMD_Q, sfp->ffd_bm)))
p_res |= EPOLLOUT | EPOLLWRNORM;
else if (atomic_read(&sfp->submitted) == 0)
p_res |= EPOLLOUT | EPOLLWRNORM;
@@ -5113,7 +5111,7 @@ sg_set_map_data(const struct sg_scatter_hold *schp, bool up_valid,
static int
sg_start_req(struct sg_request *srp, struct sg_comm_wr_t *cwrp, int dxfer_dir)
{
- bool reserved, us_xfer;
+ bool reserved, no_xfer, us_xfer;
int res = 0;
int dxfer_len = 0;
int r0w = READ;
@@ -5201,16 +5199,16 @@ sg_start_req(struct sg_request *srp, struct sg_comm_wr_t *cwrp, int dxfer_dir)
goto err_out;
scsi_rp->cmd_len = cwrp->cmd_len;
srp->cmd_opcode = scsi_rp->cmd[0];
+ no_xfer = dxfer_len <= 0 || dxfer_dir == SG_DXFER_NONE;
us_xfer = !(rq_flags & (SG_FLAG_NO_DXFER | SG_FLAG_MMAP_IO));
- assign_bit(SG_FRQ_US_XFER, srp->frq_bm, us_xfer);
+ __assign_bit(SG_FRQ_US_XFER, srp->frq_bm, !no_xfer && us_xfer);
reserved = (sfp->rsv_srp == srp);
rqq->end_io_data = srp;
scsi_rp->retries = SG_DEFAULT_RETRIES;
req_schp = srp->sgatp;
- if (dxfer_len <= 0 || dxfer_dir == SG_DXFER_NONE) {
+ if (no_xfer) {
SG_LOG(4, sfp, "%s: no data xfer [0x%pK]\n", __func__, srp);
- clear_bit(SG_FRQ_US_XFER, srp->frq_bm);
goto fini; /* path of reqs with no din nor dout */
} else if (unlikely(rq_flags & SG_FLAG_DIRECT_IO) && iov_count == 0 &&
!sdp->device->host->unchecked_isa_dma &&
@@ -5773,14 +5771,16 @@ sg_build_reserve(struct sg_fd *sfp, int buflen)
/*
* Setup an active request (soon to carry a SCSI command) to the current file
* descriptor by creating a new one or re-using a request from the free
- * list (fl). If successful returns a valid pointer in SG_RQ_BUSY state. On
- * failure returns a negated errno value twisted by ERR_PTR() macro.
+ * list (fl). If successful returns a valid pointer to a sg_request object
+ * which is in the SG_RQ_BUSY state. On failure returns a negated errno value
+ * twisted by ERR_PTR() macro. Note that once a file share is established,
+ * the read-side's reserve request can only be used in a request share.
*/
static struct sg_request *
sg_setup_req(struct sg_comm_wr_t *cwrp, enum sg_shr_var sh_var, int dxfr_len)
{
bool act_empty = false;
- bool allow_rsv = true;
+ bool allow_rsv = true; /* see note above */
bool mk_new_srp = true;
bool ws_rq = false;
bool try_harder = false;
@@ -5872,6 +5872,7 @@ sg_setup_req(struct sg_comm_wr_t *cwrp, enum sg_shr_var sh_var, int dxfr_len)
if (IS_ERR(r_srp)) {
if (PTR_ERR(r_srp) == -EBUSY)
goto err_out;
+#if IS_ENABLED(SG_LOG_ACTIVE)
if (sh_var == SG_SHR_RS_RQ)
snprintf(b, sizeof(b), "SG_SHR_RS_RQ --> sr_st=%s",
sg_rq_st_str(sr_st, false));
@@ -5881,6 +5882,7 @@ sg_setup_req(struct sg_comm_wr_t *cwrp, enum sg_shr_var sh_var, int dxfr_len)
else
snprintf(b, sizeof(b), "sh_var=%s",
sg_shr_str(sh_var, false));
+#endif
goto err_out;
}
cp = "";
@@ -5907,11 +5909,14 @@ sg_setup_req(struct sg_comm_wr_t *cwrp, enum sg_shr_var sh_var, int dxfr_len)
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_RQ_INACTIVE, SG_RQ_BUSY) == 0) {
- mk_new_srp = false;
- atomic_dec(&fp->inactives);
- goto have_existing;
+ if (r_srp && (allow_rsv || rsv_srp != r_srp)) {
+ if (r_srp->sgat_h.buflen <= SG_DEF_SECTOR_SZ) {
+ if (sg_rq_chg_state(r_srp, SG_RQ_INACTIVE,
+ SG_RQ_BUSY) == 0) {
+ mk_new_srp = false;
+ atomic_dec(&fp->inactives);
+ goto have_existing;
+ }
}
}
}
@@ -5972,12 +5977,13 @@ sg_setup_req(struct sg_comm_wr_t *cwrp, enum sg_shr_var sh_var, int dxfr_len)
good_fini:
if (mk_new_srp) { /* Need new sg_request object */
- bool allow_cmd_q = test_bit(SG_FFD_CMD_Q, fp->ffd_bm);
+ bool disallow_cmd_q = test_bit(SG_FFD_NO_CMD_Q, fp->ffd_bm);
int res;
u32 n_idx;
cp = "new";
- if (!allow_cmd_q && atomic_read(&fp->submitted) > 0) {
+ r_srp = NULL;
+ if (disallow_cmd_q && atomic_read(&fp->submitted) > 0) {
r_srp = ERR_PTR(-EDOM);
SG_LOG(6, fp, "%s: trying 2nd req but cmd_q=false\n",
__func__);
@@ -6102,7 +6108,7 @@ sg_add_sfp(struct sg_device *sdp, struct file *filp)
sfp->filp = filp;
/* other bits in sfp->ffd_bm[1] cleared by kzalloc() above */
__assign_bit(SG_FFD_FORCE_PACKID, sfp->ffd_bm, SG_DEF_FORCE_PACK_ID);
- __assign_bit(SG_FFD_CMD_Q, sfp->ffd_bm, SG_DEF_COMMAND_Q);
+ __assign_bit(SG_FFD_NO_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_TIME_IN_NS, sfp->ffd_bm, SG_DEF_TIME_UNIT);
__assign_bit(SG_FFD_Q_AT_TAIL, sfp->ffd_bm, SG_DEFAULT_Q_AT);
@@ -6616,7 +6622,7 @@ sg_proc_debug_fd(struct sg_fd *fp, char *obp, int len, unsigned long idx,
n += scnprintf(obp + n, len - n, "timeout=%ds rs", to / 1000);
n += scnprintf(obp + n, len - n, "v_buflen=%d%s idx=%lu\n cmd_q=%d ",
fp->rsv_srp->sgatp->buflen, cp, idx,
- (int)test_bit(SG_FFD_CMD_Q, fp->ffd_bm));
+ (int)!test_bit(SG_FFD_NO_CMD_Q, fp->ffd_bm));
n += scnprintf(obp + n, len - n,
"f_packid=%d k_orphan=%d ffd_bm=0x%lx\n",
(int)test_bit(SG_FFD_FORCE_PACKID, fp->ffd_bm),
--
2.25.1
