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scsi: scsi_debug: delay stress fix
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Introduce a state enum into sdebug_defer objects to indicate which, if
any, defer method has been used with the associated command.  Also add 2
bools to indicate which of the defer methods has been initialized. Those
objects are re-used but the initialization only needs to be done
once. This simplifies command cancellation handling.

Now the delay associated with a deferred response of a command cannot be
changed (once started) by changing the delay (and ndelay) parameters in
sysfs. Command aborts and driver shutdown are still honoured immediately
when received.

[mkp: applied by hand]

Signed-off-by: Douglas Gilbert <[email protected]>
Reviewed-by: Bart Van Assche <[email protected]>
Signed-off-by: Martin K. Petersen <[email protected]>
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@doug-gilbert @martinkpetersen
doug-gilbert authored and martinkpetersen committed Jan 17, 2018
1 parent dbc1ebe commit 10bde98
Showing 1 changed file with 46 additions and 26 deletions.
72 changes: 46 additions & 26 deletions drivers/scsi/scsi_debug.c
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Original file line number Diff line number Diff line change
Expand Up @@ -267,12 +267,18 @@ struct sdebug_host_info {
#define to_sdebug_host(d) \
container_of(d, struct sdebug_host_info, dev)

enum sdeb_defer_type {SDEB_DEFER_NONE = 0, SDEB_DEFER_HRT = 1,
SDEB_DEFER_WQ = 2};

struct sdebug_defer {
struct hrtimer hrt;
struct execute_work ew;
int sqa_idx; /* index of sdebug_queue array */
int qc_idx; /* index of sdebug_queued_cmd array within sqa_idx */
int issuing_cpu;
bool init_hrt;
bool init_wq;
enum sdeb_defer_type defer_t;
};

struct sdebug_queued_cmd {
Expand Down Expand Up @@ -3748,6 +3754,7 @@ static void sdebug_q_cmd_complete(struct sdebug_defer *sd_dp)
struct scsi_cmnd *scp;
struct sdebug_dev_info *devip;

sd_dp->defer_t = SDEB_DEFER_NONE;
qc_idx = sd_dp->qc_idx;
sqp = sdebug_q_arr + sd_dp->sqa_idx;
if (sdebug_statistics) {
Expand Down Expand Up @@ -3932,13 +3939,14 @@ static void scsi_debug_slave_destroy(struct scsi_device *sdp)
}
}

static void stop_qc_helper(struct sdebug_defer *sd_dp)
static void stop_qc_helper(struct sdebug_defer *sd_dp,
enum sdeb_defer_type defer_t)
{
if (!sd_dp)
return;
if ((sdebug_jdelay > 0) || (sdebug_ndelay > 0))
if (defer_t == SDEB_DEFER_HRT)
hrtimer_cancel(&sd_dp->hrt);
else if (sdebug_jdelay < 0)
else if (defer_t == SDEB_DEFER_WQ)
cancel_work_sync(&sd_dp->ew.work);
}

Expand All @@ -3948,6 +3956,7 @@ static bool stop_queued_cmnd(struct scsi_cmnd *cmnd)
{
unsigned long iflags;
int j, k, qmax, r_qmax;
enum sdeb_defer_type l_defer_t;
struct sdebug_queue *sqp;
struct sdebug_queued_cmd *sqcp;
struct sdebug_dev_info *devip;
Expand All @@ -3971,8 +3980,13 @@ static bool stop_queued_cmnd(struct scsi_cmnd *cmnd)
atomic_dec(&devip->num_in_q);
sqcp->a_cmnd = NULL;
sd_dp = sqcp->sd_dp;
if (sd_dp) {
l_defer_t = sd_dp->defer_t;
sd_dp->defer_t = SDEB_DEFER_NONE;
} else
l_defer_t = SDEB_DEFER_NONE;
spin_unlock_irqrestore(&sqp->qc_lock, iflags);
stop_qc_helper(sd_dp);
stop_qc_helper(sd_dp, l_defer_t);
clear_bit(k, sqp->in_use_bm);
return true;
}
Expand All @@ -3987,6 +4001,7 @@ static void stop_all_queued(void)
{
unsigned long iflags;
int j, k;
enum sdeb_defer_type l_defer_t;
struct sdebug_queue *sqp;
struct sdebug_queued_cmd *sqcp;
struct sdebug_dev_info *devip;
Expand All @@ -4005,8 +4020,13 @@ static void stop_all_queued(void)
atomic_dec(&devip->num_in_q);
sqcp->a_cmnd = NULL;
sd_dp = sqcp->sd_dp;
if (sd_dp) {
l_defer_t = sd_dp->defer_t;
sd_dp->defer_t = SDEB_DEFER_NONE;
} else
l_defer_t = SDEB_DEFER_NONE;
spin_unlock_irqrestore(&sqp->qc_lock, iflags);
stop_qc_helper(sd_dp);
stop_qc_helper(sd_dp, l_defer_t);
clear_bit(k, sqp->in_use_bm);
spin_lock_irqsave(&sqp->qc_lock, iflags);
}
Expand Down Expand Up @@ -4258,7 +4278,7 @@ static void setup_inject(struct sdebug_queue *sqp,
* SCSI_MLQUEUE_HOST_BUSY if temporarily out of resources.
*/
static int schedule_resp(struct scsi_cmnd *cmnd, struct sdebug_dev_info *devip,
int scsi_result, int delta_jiff)
int scsi_result, int delta_jiff, int ndelay)
{
unsigned long iflags;
int k, num_in_q, qdepth, inject;
Expand Down Expand Up @@ -4336,17 +4356,20 @@ static int schedule_resp(struct scsi_cmnd *cmnd, struct sdebug_dev_info *devip,
spin_unlock_irqrestore(&sqp->qc_lock, iflags);
if (unlikely(sdebug_every_nth && sdebug_any_injecting_opt))
setup_inject(sqp, sqcp);
if (delta_jiff > 0 || sdebug_ndelay > 0) {
if (sd_dp == NULL) {
sd_dp = kzalloc(sizeof(*sd_dp), GFP_ATOMIC);
if (sd_dp == NULL)
return SCSI_MLQUEUE_HOST_BUSY;
}
if (delta_jiff > 0 || ndelay > 0) {
ktime_t kt;

if (delta_jiff > 0) {
kt = ns_to_ktime((u64)delta_jiff * (NSEC_PER_SEC / HZ));
} else
kt = sdebug_ndelay;
if (NULL == sd_dp) {
sd_dp = kzalloc(sizeof(*sd_dp), GFP_ATOMIC);
if (NULL == sd_dp)
return SCSI_MLQUEUE_HOST_BUSY;
kt = ndelay;
if (!sd_dp->init_hrt) {
sd_dp->init_hrt = true;
sqcp->sd_dp = sd_dp;
hrtimer_init(&sd_dp->hrt, CLOCK_MONOTONIC,
HRTIMER_MODE_REL_PINNED);
Expand All @@ -4356,19 +4379,19 @@ static int schedule_resp(struct scsi_cmnd *cmnd, struct sdebug_dev_info *devip,
}
if (sdebug_statistics)
sd_dp->issuing_cpu = raw_smp_processor_id();
sd_dp->defer_t = SDEB_DEFER_HRT;
hrtimer_start(&sd_dp->hrt, kt, HRTIMER_MODE_REL_PINNED);
} else { /* jdelay < 0, use work queue */
if (NULL == sd_dp) {
sd_dp = kzalloc(sizeof(*sqcp->sd_dp), GFP_ATOMIC);
if (NULL == sd_dp)
return SCSI_MLQUEUE_HOST_BUSY;
if (!sd_dp->init_wq) {
sd_dp->init_wq = true;
sqcp->sd_dp = sd_dp;
sd_dp->sqa_idx = sqp - sdebug_q_arr;
sd_dp->qc_idx = k;
INIT_WORK(&sd_dp->ew.work, sdebug_q_cmd_wq_complete);
}
if (sdebug_statistics)
sd_dp->issuing_cpu = raw_smp_processor_id();
sd_dp->defer_t = SDEB_DEFER_WQ;
schedule_work(&sd_dp->ew.work);
}
if (unlikely((SDEBUG_OPT_Q_NOISE & sdebug_opts) &&
Expand Down Expand Up @@ -4615,9 +4638,6 @@ static ssize_t delay_store(struct device_driver *ddp, const char *buf,
}
}
if (res > 0) {
/* make sure sdebug_defer instances get
* re-allocated for new delay variant */
free_all_queued();
sdebug_jdelay = jdelay;
sdebug_ndelay = 0;
}
Expand Down Expand Up @@ -4658,9 +4678,6 @@ static ssize_t ndelay_store(struct device_driver *ddp, const char *buf,
}
}
if (res > 0) {
/* make sure sdebug_defer instances get
* re-allocated for new delay variant */
free_all_queued();
sdebug_ndelay = ndelay;
sdebug_jdelay = ndelay ? JDELAY_OVERRIDDEN
: DEF_JDELAY;
Expand Down Expand Up @@ -5702,12 +5719,15 @@ static int scsi_debug_queuecommand(struct Scsi_Host *shost,
errsts = r_pfp(scp, devip);

fini:
return schedule_resp(scp, devip, errsts,
((F_DELAY_OVERR & flags) ? 0 : sdebug_jdelay));
if (F_DELAY_OVERR & flags)
return schedule_resp(scp, devip, errsts, 0, 0);
else
return schedule_resp(scp, devip, errsts, sdebug_jdelay,
sdebug_ndelay);
check_cond:
return schedule_resp(scp, devip, check_condition_result, 0);
return schedule_resp(scp, devip, check_condition_result, 0, 0);
err_out:
return schedule_resp(scp, NULL, DID_NO_CONNECT << 16, 0);
return schedule_resp(scp, NULL, DID_NO_CONNECT << 16, 0, 0);
}

static struct scsi_host_template sdebug_driver_template = {
Expand Down

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