UbiquitousOS
/
OpenCloudOS-Kernel
mirror of https://gitee.com/OpenCloudOS/OpenCloudOS-Kernel.git
11
0
Fork 0
Code Issues Projects Releases Wiki Activity

rcutorture: Dump reader protection sequence if failures or close calls 

Now that RCU can have readers with multiple segments, it is quite
possible that a specific sequence of reader segments might result in
an rcutorture failure (reader spans a full grace period as detected
by one of the grace-period primitives) or an rcutorture close call
(reader potentially spans a full grace period based on reading out
the RCU implementation's grace-period counter, but with no ordering).
In such cases, it would clearly ease debugging if the offending specific
sequence was known.  For the first reader encountering a failure or a
close call, this commit therefore dumps out the segments, delay durations,
and whether or not the reader was preempted.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
[ paulmck: Mark variables static, as suggested by kbuild test robot. ]
This commit is contained in:
Paul E. McKenney 2018-07-13 12:09:14 -07:00
parent a0ef9ec241
commit c116dba68d
1 changed files with 96 additions and 23 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

119
kernel/rcu/rcutorture.c
View File

@ -78,6 +78,7 @@ MODULE_AUTHOR("Paul E. McKenney <paulmck@us.ibm.com> and Josh Triplett <josh@jos
RCUTORTURE_RDR_RBH | RCUTORTURE_RDR_SCHED)
#define RCUTORTURE_RDR_MAX_LOOPS 0x7 /* Maximum reader extensions. */
/* Must be power of two minus one. */
#define RCUTORTURE_RDR_MAX_SEGS (RCUTORTURE_RDR_MAX_LOOPS + 3)
torture_param(int, cbflood_inter_holdoff, HZ,
"Holdoff between floods (jiffies)");
@ -200,6 +201,18 @@ static const char * const rcu_torture_writer_state_names[] = {
"RTWS_STOPPING",
};
/* Record reader segment types and duration for first failing read. */
struct rt_read_seg {
int rt_readstate;
unsigned long rt_delay_jiffies;
unsigned long rt_delay_ms;
unsigned long rt_delay_us;
bool rt_preempted;
};
static int err_segs_recorded;
static struct rt_read_seg err_segs[RCUTORTURE_RDR_MAX_SEGS];
static int rt_read_nsegs;
static const char *rcu_torture_writer_state_getname(void)
{
unsigned int i = READ_ONCE(rcu_torture_writer_state);
@ -281,7 +294,8 @@ struct rcu_torture_ops {
void (*init)(void);
void (*cleanup)(void);
int (*readlock)(void);
void (*read_delay)(struct torture_random_state *rrsp);
void (*read_delay)(struct torture_random_state *rrsp,
struct rt_read_seg *rtrsp);
void (*readunlock)(int idx);
unsigned long (*get_gp_seq)(void);
unsigned long (*gp_diff)(unsigned long new, unsigned long old);
@ -313,7 +327,8 @@ static int rcu_torture_read_lock(void) __acquires(RCU)
return 0;
}
static void rcu_read_delay(struct torture_random_state *rrsp)
static void
rcu_read_delay(struct torture_random_state *rrsp, struct rt_read_seg *rtrsp)
{
unsigned long started;
unsigned long completed;
@ -329,15 +344,20 @@ static void rcu_read_delay(struct torture_random_state *rrsp)
started = cur_ops->get_gp_seq();
ts = rcu_trace_clock_local();
mdelay(longdelay_ms);
rtrsp->rt_delay_ms = longdelay_ms;
completed = cur_ops->get_gp_seq();
do_trace_rcu_torture_read(cur_ops->name, NULL, ts,
started, completed);
}
if (!(torture_random(rrsp) % (nrealreaders * 2 * shortdelay_us)))
if (!(torture_random(rrsp) % (nrealreaders * 2 * shortdelay_us))) {
udelay(shortdelay_us);
rtrsp->rt_delay_us = shortdelay_us;
}
if (!preempt_count() &&
!(torture_random(rrsp) % (nrealreaders * 500)))
!(torture_random(rrsp) % (nrealreaders * 500))) {
torture_preempt_schedule(); /* QS only if preemptible. */
rtrsp->rt_preempted = true;
}
}
static void rcu_torture_read_unlock(int idx) __releases(RCU)
@ -494,7 +514,8 @@ static int srcu_torture_read_lock(void) __acquires(srcu_ctlp)
return srcu_read_lock(srcu_ctlp);
}
static void srcu_read_delay(struct torture_random_state *rrsp)
static void
srcu_read_delay(struct torture_random_state *rrsp, struct rt_read_seg *rtrsp)
{
long delay;
const long uspertick = 1000000 / HZ;
@ -504,10 +525,12 @@ static void srcu_read_delay(struct torture_random_state *rrsp)
delay = torture_random(rrsp) %
(nrealreaders * 2 * longdelay * uspertick);
if (!delay && in_task())
if (!delay && in_task()) {
schedule_timeout_interruptible(longdelay);
else
rcu_read_delay(rrsp);
rtrsp->rt_delay_jiffies = longdelay;
} else {
rcu_read_delay(rrsp, rtrsp);
}
}
static void srcu_torture_read_unlock(int idx) __releases(srcu_ctlp)
@ -1120,7 +1143,8 @@ static void rcu_torture_timer_cb(struct rcu_head *rhp)
* change, do a ->read_delay().
*/
static void rcutorture_one_extend(int *readstate, int newstate,
struct torture_random_state *trsp)
struct torture_random_state *trsp,
struct rt_read_seg *rtrsp)
{
int idxnew = -1;
int idxold = *readstate;
@ -1129,6 +1153,7 @@ static void rcutorture_one_extend(int *readstate, int newstate,
WARN_ON_ONCE(idxold < 0);
WARN_ON_ONCE((idxold >> RCUTORTURE_RDR_SHIFT) > 1);
rtrsp->rt_readstate = newstate;
/* First, put new protection in place to avoid critical-section gap. */
if (statesnew & RCUTORTURE_RDR_BH)
@ -1160,7 +1185,7 @@ static void rcutorture_one_extend(int *readstate, int newstate,
/* Delay if neither beginning nor end and there was a change. */
if ((statesnew || statesold) && *readstate && newstate)
cur_ops->read_delay(trsp);
cur_ops->read_delay(trsp, rtrsp);
/* Update the reader state. */
if (idxnew == -1)
@ -1189,11 +1214,11 @@ rcutorture_extend_mask(int oldmask, struct torture_random_state *trsp)
{
int mask = rcutorture_extend_mask_max();
unsigned long randmask1 = torture_random(trsp) >> 8;
unsigned long randmask2 = randmask1 >> 1;
unsigned long randmask2 = randmask1 >> 3;
WARN_ON_ONCE(mask >> RCUTORTURE_RDR_SHIFT);
/* Half the time lots of bits, half the time only one bit. */
if (randmask1 & 0x1)
/* Most of the time lots of bits, half the time only one bit. */
if (!(randmask1 & 0x7))
mask = mask & randmask2;
else
mask = mask & (1 << (randmask2 % RCUTORTURE_RDR_NBITS));
@ -1213,20 +1238,25 @@ rcutorture_extend_mask(int oldmask, struct torture_random_state *trsp)
* Do a randomly selected number of extensions of an existing RCU read-side
* critical section.
*/
static void rcutorture_loop_extend(int *readstate,
struct torture_random_state *trsp)
static struct rt_read_seg *
rcutorture_loop_extend(int *readstate, struct torture_random_state *trsp,
struct rt_read_seg *rtrsp)
{
int i;
int j;
int mask = rcutorture_extend_mask_max();
WARN_ON_ONCE(!*readstate); /* -Existing- RCU read-side critsect! */
if (!((mask - 1) & mask))
return; /* Current RCU reader not extendable. */
i = (torture_random(trsp) >> 3) & RCUTORTURE_RDR_MAX_LOOPS;
while (i--) {
return rtrsp; /* Current RCU reader not extendable. */
/* Bias towards larger numbers of loops. */
i = (torture_random(trsp) >> 3);
i = ((i | (i >> 3)) & RCUTORTURE_RDR_MAX_LOOPS) + 1;
for (j = 0; j < i; j++) {
mask = rcutorture_extend_mask(*readstate, trsp);
rcutorture_one_extend(readstate, mask, trsp);
rcutorture_one_extend(readstate, mask, trsp, &rtrsp[j]);
}
return &rtrsp[j];
}
/*
@ -1236,16 +1266,20 @@ static void rcutorture_loop_extend(int *readstate,
*/
static bool rcu_torture_one_read(struct torture_random_state *trsp)
{
int i;
unsigned long started;
unsigned long completed;
int newstate;
struct rcu_torture *p;
int pipe_count;
int readstate = 0;
struct rt_read_seg rtseg[RCUTORTURE_RDR_MAX_SEGS] = { { 0 } };
struct rt_read_seg *rtrsp = &rtseg[0];
struct rt_read_seg *rtrsp1;
unsigned long long ts;
newstate = rcutorture_extend_mask(readstate, trsp);
rcutorture_one_extend(&readstate, newstate, trsp);
rcutorture_one_extend(&readstate, newstate, trsp, rtrsp++);
started = cur_ops->get_gp_seq();
ts = rcu_trace_clock_local();
p = rcu_dereference_check(rcu_torture_current,
@ -1255,12 +1289,12 @@ static bool rcu_torture_one_read(struct torture_random_state *trsp)
torturing_tasks());
if (p == NULL) {
/* Wait for rcu_torture_writer to get underway */
rcutorture_one_extend(&readstate, 0, trsp);
rcutorture_one_extend(&readstate, 0, trsp, rtrsp);
return false;
}
if (p->rtort_mbtest == 0)
atomic_inc(&n_rcu_torture_mberror);
rcutorture_loop_extend(&readstate, trsp);
rtrsp = rcutorture_loop_extend(&readstate, trsp, rtrsp);
preempt_disable();
pipe_count = p->rtort_pipe_count;
if (pipe_count > RCU_TORTURE_PIPE_LEN) {
@ -1281,8 +1315,17 @@ static bool rcu_torture_one_read(struct torture_random_state *trsp)
}
__this_cpu_inc(rcu_torture_batch[completed]);
preempt_enable();
rcutorture_one_extend(&readstate, 0, trsp);
rcutorture_one_extend(&readstate, 0, trsp, rtrsp);
WARN_ON_ONCE(readstate & RCUTORTURE_RDR_MASK);
/* If error or close call, record the sequence of reader protections. */
if ((pipe_count > 1 || completed > 1) && !xchg(&err_segs_recorded, 1)) {
i = 0;
for (rtrsp1 = &rtseg[0]; rtrsp1 < rtrsp; rtrsp1++)
err_segs[i++] = *rtrsp1;
rt_read_nsegs = i;
}
return true;
}
@ -1747,6 +1790,7 @@ static enum cpuhp_state rcutor_hp;
static void
rcu_torture_cleanup(void)
{
int firsttime;
int flags = 0;
unsigned long gp_seq = 0;
int i;
@ -1800,6 +1844,33 @@ rcu_torture_cleanup(void)
rcu_torture_stats_print(); /* -After- the stats thread is stopped! */
if (err_segs_recorded) {
pr_alert("Failure/close-call rcutorture reader segments:\n");
if (rt_read_nsegs == 0)
pr_alert("\t: No segments recorded!!!\n");
firsttime = 1;
for (i = 0; i < rt_read_nsegs; i++) {
pr_alert("\t%d: %#x ", i, err_segs[i].rt_readstate);
if (err_segs[i].rt_delay_jiffies != 0) {
pr_cont("%s%ldjiffies", firsttime ? "" : "+",
err_segs[i].rt_delay_jiffies);
firsttime = 0;
}
if (err_segs[i].rt_delay_ms != 0) {
pr_cont("%s%ldms", firsttime ? "" : "+",
err_segs[i].rt_delay_ms);
firsttime = 0;
}
if (err_segs[i].rt_delay_us != 0) {
pr_cont("%s%ldus", firsttime ? "" : "+",
err_segs[i].rt_delay_us);
firsttime = 0;
}
pr_cont("%s\n",
err_segs[i].rt_preempted ? "preempted" : "");
}
}
if (atomic_read(&n_rcu_torture_error) || n_rcu_torture_barrier_error)
rcu_torture_print_module_parms(cur_ops, "End of test: FAILURE");
else if (torture_onoff_failures())
@ -1943,6 +2014,8 @@ rcu_torture_init(void)
per_cpu(rcu_torture_batch, cpu)[i] = 0;
}
}
err_segs_recorded = 0;
rt_read_nsegs = 0;
/* Start up the kthreads. */