Currently, print nothing about what event wakes up in report. However, it makes hard to interpret dept's report.
Make it print wait's stacktrace that the event wakes up.
Signed-off-by: Byungchul Park byungchul@sk.com --- include/linux/sched.h | 2 ++ kernel/dependency/dept.c | 59 ++++++++++++++++++++++++++----- kernel/dependency/dept_internal.h | 5 +++ 3 files changed, 57 insertions(+), 9 deletions(-)
diff --git a/include/linux/sched.h b/include/linux/sched.h index a4e6dce98f36..b2fbcf0f00f4 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -871,6 +871,7 @@ struct dept_task { const char *stage_w_fn; unsigned long stage_ip; bool stage_timeout; + struct dept_stack *stage_wait_stack; arch_spinlock_t stage_lock;
/* @@ -912,6 +913,7 @@ struct dept_task { .stage_w_fn = NULL, \ .stage_ip = 0UL, \ .stage_timeout = false, \ + .stage_wait_stack = NULL, \ .stage_lock = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED,\ .missing_ecxt = 0, \ .hardirqs_enabled = false, \ diff --git a/kernel/dependency/dept.c b/kernel/dependency/dept.c index e425d3ab05e5..5bf32633e1fb 100644 --- a/kernel/dependency/dept.c +++ b/kernel/dependency/dept.c @@ -523,6 +523,7 @@ static void initialize_ecxt(struct dept_ecxt *e) e->enirqf = 0UL; e->event_ip = 0UL; e->event_stack = NULL; + e->ewait_stack = NULL; } SET_CONSTRUCTOR(ecxt, initialize_ecxt);
@@ -578,6 +579,8 @@ static void destroy_ecxt(struct dept_ecxt *e) put_stack(e->ecxt_stack); if (e->event_stack) put_stack(e->event_stack); + if (e->ewait_stack) + put_stack(e->ewait_stack); } SET_DESTRUCTOR(ecxt, destroy_ecxt);
@@ -794,6 +797,11 @@ static void print_dep(struct dept_dep *d)
pr_warn("[E] %s(%s:%d):\n", e_fn, fc_n, fc->sub_id); print_ip_stack(e->event_ip, e->event_stack); + + if (valid_stack(e->ewait_stack)) { + pr_warn("(wait to wake up)\n"); + print_ip_stack(0, e->ewait_stack); + } }
if (!irqf) { @@ -807,6 +815,11 @@ static void print_dep(struct dept_dep *d)
pr_warn("[E] %s(%s:%d):\n", e_fn, fc_n, fc->sub_id); print_ip_stack(e->event_ip, e->event_stack); + + if (valid_stack(e->ewait_stack)) { + pr_warn("(wait to wake up)\n"); + print_ip_stack(0, e->ewait_stack); + } } }
@@ -1657,7 +1670,8 @@ static void add_wait(struct dept_class *c, unsigned long ip,
static struct dept_ecxt_held *add_ecxt(struct dept_map *m, struct dept_class *c, unsigned long ip, const char *c_fn, - const char *e_fn, int sub_l) + const char *e_fn, int sub_l, + struct dept_stack *ewait_stack) { struct dept_task *dt = dept_task(); struct dept_ecxt_held *eh; @@ -1691,6 +1705,7 @@ static struct dept_ecxt_held *add_ecxt(struct dept_map *m, e->class = get_class(c); e->ecxt_ip = ip; e->ecxt_stack = ip ? get_current_stack() : NULL; + e->ewait_stack = ewait_stack ? get_stack(ewait_stack) : NULL; e->event_fn = e_fn; e->ecxt_fn = c_fn;
@@ -1797,7 +1812,7 @@ static int find_hist_pos(unsigned int wg)
static void do_event(struct dept_map *m, struct dept_map *real_m, struct dept_class *c, unsigned int wg, unsigned long ip, - const char *e_fn) + const char *e_fn, struct dept_stack *ewait_stack) { struct dept_task *dt = dept_task(); struct dept_wait_hist *wh; @@ -1825,7 +1840,7 @@ static void do_event(struct dept_map *m, struct dept_map *real_m, */ if (find_ecxt_pos(real_m, c, false) != -1) return; - eh = add_ecxt(m, c, 0UL, NULL, e_fn, 0); + eh = add_ecxt(m, c, 0UL, NULL, e_fn, 0, ewait_stack);
if (!eh) return; @@ -2360,7 +2375,8 @@ static void __dept_wait(struct dept_map *m, unsigned long w_f, */ static void __dept_event(struct dept_map *m, struct dept_map *real_m, unsigned long e_f, unsigned long ip, const char *e_fn, - bool sched_map, unsigned int wg) + bool sched_map, unsigned int wg, + struct dept_stack *ewait_stack) { struct dept_class *c; struct dept_key *k; @@ -2382,7 +2398,7 @@ static void __dept_event(struct dept_map *m, struct dept_map *real_m, c = check_new_class(&m->map_key, k, sub_id(m, e), m->name, sched_map);
if (c) - do_event(m, real_m, c, wg, ip, e_fn); + do_event(m, real_m, c, wg, ip, e_fn, ewait_stack); }
void dept_wait(struct dept_map *m, unsigned long w_f, @@ -2498,6 +2514,9 @@ static void __dept_clean_stage(struct dept_task *dt) dt->stage_w_fn = NULL; dt->stage_ip = 0UL; dt->stage_timeout = false; + if (dt->stage_wait_stack) + put_stack(dt->stage_wait_stack); + dt->stage_wait_stack = NULL; }
void dept_clean_stage(void) @@ -2561,6 +2580,14 @@ void dept_request_event_wait_commit(void)
wg = next_wgen(); WRITE_ONCE(dt->stage_m.wgen, wg); + + /* + * __schedule() can be hit multiple times between + * dept_stage_wait() and dept_clean_stage(). In that case, + * keep the first stacktrace only. That's enough. + */ + if (!dt->stage_wait_stack) + dt->stage_wait_stack = get_current_stack(); arch_spin_unlock(&dt->stage_lock);
__dept_wait(&dt->stage_m, 1UL, ip, w_fn, 0, true, sched_map, timeout); @@ -2579,6 +2606,7 @@ void dept_ttwu_stage_wait(struct task_struct *requestor, unsigned long ip) struct dept_map m; struct dept_map *real_m; bool sched_map; + struct dept_stack *ewait_stack;
if (unlikely(!dept_working())) return; @@ -2597,6 +2625,10 @@ void dept_ttwu_stage_wait(struct task_struct *requestor, unsigned long ip) m = dt_req->stage_m; sched_map = dt_req->stage_sched_map; real_m = dt_req->stage_real_m; + ewait_stack = dt_req->stage_wait_stack; + if (ewait_stack) + get_stack(ewait_stack); + __dept_clean_stage(dt_req); arch_spin_unlock(&dt_req->stage_lock);
@@ -2607,8 +2639,12 @@ void dept_ttwu_stage_wait(struct task_struct *requestor, unsigned long ip) if (!m.keys) goto exit;
- __dept_event(&m, real_m, 1UL, ip, "try_to_wake_up", sched_map, m.wgen); + __dept_event(&m, real_m, 1UL, ip, "try_to_wake_up", sched_map, + m.wgen, ewait_stack); exit: + if (ewait_stack) + put_stack(ewait_stack); + dept_exit(flags); }
@@ -2688,7 +2724,7 @@ void dept_map_ecxt_modify(struct dept_map *m, unsigned long e_f, k = m->keys ?: &m->map_key; c = check_new_class(&m->map_key, k, sub_id(m, new_e), m->name, false);
- if (c && add_ecxt(m, c, new_ip, new_c_fn, new_e_fn, new_sub_l)) + if (c && add_ecxt(m, c, new_ip, new_c_fn, new_e_fn, new_sub_l, NULL)) goto exit;
/* @@ -2740,7 +2776,7 @@ void dept_ecxt_enter(struct dept_map *m, unsigned long e_f, unsigned long ip, k = m->keys ?: &m->map_key; c = check_new_class(&m->map_key, k, sub_id(m, e), m->name, false);
- if (c && add_ecxt(m, c, ip, c_fn, e_fn, sub_l)) + if (c && add_ecxt(m, c, ip, c_fn, e_fn, sub_l, NULL)) goto exit; missing_ecxt: dt->missing_ecxt++; @@ -2840,7 +2876,7 @@ void dept_event(struct dept_map *m, unsigned long e_f,
flags = dept_enter();
- __dept_event(m, m, e_f, ip, e_fn, false, READ_ONCE(*wg_p)); + __dept_event(m, m, e_f, ip, e_fn, false, READ_ONCE(*wg_p), NULL);
/* * Keep the map diabled until the next sleep. @@ -2912,6 +2948,11 @@ void dept_task_exit(struct task_struct *t) dt->stack = NULL; }
+ if (dt->stage_wait_stack) { + put_stack(dt->stage_wait_stack); + dt->stage_wait_stack = NULL; + } + for (i = 0; i < dt->ecxt_held_pos; i++) { if (dt->ecxt_held[i].class) { put_class(dt->ecxt_held[i].class); diff --git a/kernel/dependency/dept_internal.h b/kernel/dependency/dept_internal.h index 3d1cd1a9b6d4..c02783ecf0c4 100644 --- a/kernel/dependency/dept_internal.h +++ b/kernel/dependency/dept_internal.h @@ -194,6 +194,11 @@ struct dept_ecxt { */ unsigned long event_ip; struct dept_stack *event_stack; + + /* + * wait that this event ttwu + */ + struct dept_stack *ewait_stack; }; }; };