torture: Dump ftrace buffer when the RCU grace period stalls

[deliverable/linux.git] / kernel / rcu / rcutorture.c

diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
index bd30bc61bc05c273159541f260d047fa4747bc82..9decce0f110ca7810bf23d01871df8647c39fc5a 100644 (file)
--- a/kernel/rcu/rcutorture.c
+++ b/kernel/rcu/rcutorture.c
@@ -138,6 +138,15 @@ static long n_barrier_attempts;
 static long n_barrier_successes;
 static struct list_head rcu_torture_removed;
 
+static int rcu_torture_writer_state;
+#define RTWS_FIXED_DELAY       0
+#define RTWS_DELAY             1
+#define RTWS_REPLACE           2
+#define RTWS_DEF_FREE          3
+#define RTWS_EXP_SYNC          4
+#define RTWS_STUTTER           5
+#define RTWS_STOPPING          6
+
 #if defined(MODULE) || defined(CONFIG_RCU_TORTURE_TEST_RUNNABLE)
 #define RCUTORTURE_RUNNABLE_INIT 1
 #else
@@ -214,6 +223,7 @@ rcu_torture_free(struct rcu_torture *p)
  */
 
 struct rcu_torture_ops {
+       int ttype;
        void (*init)(void);
        int (*readlock)(void);
        void (*read_delay)(struct torture_random_state *rrsp);
@@ -312,6 +322,7 @@ static void rcu_sync_torture_init(void)
 }
 
 static struct rcu_torture_ops rcu_ops = {
+       .ttype          = RCU_FLAVOR,
        .init           = rcu_sync_torture_init,
        .readlock       = rcu_torture_read_lock,
        .read_delay     = rcu_read_delay,
@@ -355,6 +366,7 @@ static void rcu_bh_torture_deferred_free(struct rcu_torture *p)
 }
 
 static struct rcu_torture_ops rcu_bh_ops = {
+       .ttype          = RCU_BH_FLAVOR,
        .init           = rcu_sync_torture_init,
        .readlock       = rcu_bh_torture_read_lock,
        .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
@@ -397,6 +409,7 @@ call_rcu_busted(struct rcu_head *head, void (*func)(struct rcu_head *rcu))
 }
 
 static struct rcu_torture_ops rcu_busted_ops = {
+       .ttype          = INVALID_RCU_FLAVOR,
        .init           = rcu_sync_torture_init,
        .readlock       = rcu_torture_read_lock,
        .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
@@ -479,9 +492,11 @@ static void srcu_torture_stats(char *page)
        page += sprintf(page, "%s%s per-CPU(idx=%d):",
                       torture_type, TORTURE_FLAG, idx);
        for_each_possible_cpu(cpu) {
-               page += sprintf(page, " %d(%lu,%lu)", cpu,
-                              per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[!idx],
-                              per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[idx]);
+               long c0, c1;
+
+               c0 = (long)per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[!idx];
+               c1 = (long)per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[idx];
+               page += sprintf(page, " %d(%ld,%ld)", cpu, c0, c1);
        }
        sprintf(page, "\n");
 }
@@ -492,6 +507,7 @@ static void srcu_torture_synchronize_expedited(void)
 }
 
 static struct rcu_torture_ops srcu_ops = {
+       .ttype          = SRCU_FLAVOR,
        .init           = rcu_sync_torture_init,
        .readlock       = srcu_torture_read_lock,
        .read_delay     = srcu_read_delay,
@@ -527,6 +543,7 @@ static void rcu_sched_torture_deferred_free(struct rcu_torture *p)
 }
 
 static struct rcu_torture_ops sched_ops = {
+       .ttype          = RCU_SCHED_FLAVOR,
        .init           = rcu_sync_torture_init,
        .readlock       = sched_torture_read_lock,
        .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
@@ -699,12 +716,15 @@ rcu_torture_writer(void *arg)
        set_user_nice(current, MAX_NICE);
 
        do {
+               rcu_torture_writer_state = RTWS_FIXED_DELAY;
                schedule_timeout_uninterruptible(1);
                rp = rcu_torture_alloc();
                if (rp == NULL)
                        continue;
                rp->rtort_pipe_count = 0;
+               rcu_torture_writer_state = RTWS_DELAY;
                udelay(torture_random(&rand) & 0x3ff);
+               rcu_torture_writer_state = RTWS_REPLACE;
                old_rp = rcu_dereference_check(rcu_torture_current,
                                               current == writer_task);
                rp->rtort_mbtest = 1;
@@ -721,8 +741,10 @@ rcu_torture_writer(void *arg)
                        else
                                exp = gp_exp;
                        if (!exp) {
+                               rcu_torture_writer_state = RTWS_DEF_FREE;
                                cur_ops->deferred_free(old_rp);
                        } else {
+                               rcu_torture_writer_state = RTWS_EXP_SYNC;
                                cur_ops->exp_sync();
                                list_add(&old_rp->rtort_free,
                                         &rcu_torture_removed);
@@ -743,8 +765,10 @@ rcu_torture_writer(void *arg)
                        }
                }
                rcutorture_record_progress(++rcu_torture_current_version);
+               rcu_torture_writer_state = RTWS_STUTTER;
                stutter_wait("rcu_torture_writer");
        } while (!torture_must_stop());
+       rcu_torture_writer_state = RTWS_STOPPING;
        torture_kthread_stopping("rcu_torture_writer");
        return 0;
 }
@@ -784,7 +808,7 @@ rcu_torture_fakewriter(void *arg)
        return 0;
 }
 
-void rcutorture_trace_dump(void)
+static void rcutorture_trace_dump(void)
 {
        static atomic_t beenhere = ATOMIC_INIT(0);
 
@@ -937,6 +961,7 @@ rcu_torture_printk(char *page)
        int i;
        long pipesummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
        long batchsummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
+       static unsigned long rtcv_snap = ULONG_MAX;
 
        for_each_possible_cpu(cpu) {
                for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
@@ -997,6 +1022,21 @@ rcu_torture_printk(char *page)
        page += sprintf(page, "\n");
        if (cur_ops->stats)
                cur_ops->stats(page);
+       if (rtcv_snap == rcu_torture_current_version &&
+           rcu_torture_current != NULL) {
+               int __maybe_unused flags;
+               unsigned long __maybe_unused gpnum;
+               unsigned long __maybe_unused completed;
+
+               rcutorture_get_gp_data(cur_ops->ttype,
+                                      &flags, &gpnum, &completed);
+               page += sprintf(page,
+                               "??? Writer stall state %d g%lu c%lu f%#x\n",
+                               rcu_torture_writer_state,
+                               gpnum, completed, flags);
+               rcutorture_trace_dump();
+       }
+       rtcv_snap = rcu_torture_current_version;
 }
 
 /*
@@ -1146,7 +1186,7 @@ static int __init rcu_torture_stall_init(void)
 }
 
 /* Callback function for RCU barrier testing. */
-void rcu_torture_barrier_cbf(struct rcu_head *rcu)
+static void rcu_torture_barrier_cbf(struct rcu_head *rcu)
 {
        atomic_inc(&barrier_cbs_invoked);
 }