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authorRickard Green <[email protected]>2016-12-28 18:27:54 +0100
committerRickard Green <[email protected]>2016-12-28 19:22:33 +0100
commit32c71f85bd2d17a6c58f6d1fa450dfb8cf3de6cb (patch)
tree82b192f799527837be03d405650095dc1b9c7ab0
parent3eef3cd38c6beb48bfe4c2e26ede2ab2d107c146 (diff)
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Fix premature removal of process struct
Refc on process struct could reach zero while it was still referred by dirty scheduler
-rw-r--r--erts/emulator/beam/erl_process.c119
1 files changed, 82 insertions, 37 deletions
diff --git a/erts/emulator/beam/erl_process.c b/erts/emulator/beam/erl_process.c
index b345c35a7e..6810210e4d 100644
--- a/erts/emulator/beam/erl_process.c
+++ b/erts/emulator/beam/erl_process.c
@@ -2060,6 +2060,7 @@ handle_thr_prgr_later_op(ErtsAuxWorkData *awdp, erts_aint32_t aux_work, int wait
#endif
for (lops = 0; lops < ERTS_MAX_THR_PRGR_LATER_OPS; lops++) {
ErtsThrPrgrLaterOp *lop = awdp->later_op.first;
+
if (!erts_thr_progress_has_reached_this(current, lop->later))
return aux_work & ~ERTS_SSI_AUX_WORK_THR_PRGR_LATER_OP;
awdp->later_op.first = lop->next;
@@ -6234,6 +6235,12 @@ check_dirty_enqueue_in_prio_queue(Process *c_p,
int queue;
erts_aint32_t dact, max_qbit;
+ /* Do not enqueue free process... */
+ if (actual & ERTS_PSFLG_FREE) {
+ *newp &= ~ERTS_PSFLGS_DIRTY_WORK;
+ return ERTS_ENQUEUE_NOT;
+ }
+
/* Termination should be done on an ordinary scheduler */
if ((*newp) & ERTS_PSFLG_EXITING) {
*newp &= ~ERTS_PSFLGS_DIRTY_WORK;
@@ -6426,6 +6433,9 @@ select_enqueue_run_queue(int enqueue, int enq_prio, Process *p, erts_aint32_t st
/*
* schedule_out_process() return with c_rq locked.
+ *
+ * Return non-zero value if caller should decrease
+ * reference count on the process when done with it...
*/
static ERTS_INLINE int
schedule_out_process(ErtsRunQueue *c_rq, erts_aint32_t state, Process *p,
@@ -6480,12 +6490,18 @@ schedule_out_process(ErtsRunQueue *c_rq, erts_aint32_t state, Process *p,
erts_smp_runq_lock(c_rq);
- return 0;
-
+#if !defined(ERTS_SMP)
+ /* Decrement refc if process struct is free... */
+ return !!(n & ERTS_PSFLG_FREE);
+#else
+ /* Decrement refc if scheduled out from dirty scheduler... */
+ return !is_normal_sched;
+#endif
}
else {
Process* sched_p;
+ ASSERT(!(n & ERTS_PSFLG_FREE));
ASSERT(!(n & ERTS_PSFLG_SUSPENDED) || (n & (ERTS_PSFLG_ACTIVE_SYS
| ERTS_PSFLG_DIRTY_ACTIVE_SYS)));
@@ -6501,11 +6517,14 @@ schedule_out_process(ErtsRunQueue *c_rq, erts_aint32_t state, Process *p,
erts_smp_runq_lock(runq);
+ if (is_normal_sched && sched_p == p && ERTS_RUNQ_IX_IS_DIRTY(runq->ix))
+ erts_proc_inc_refc(p); /* Needs to be done before enqueue_process() */
+
/* Enqueue the process */
enqueue_process(runq, (int) enq_prio, sched_p);
if (runq == c_rq)
- return 1;
+ return 0;
erts_smp_runq_unlock(runq);
@@ -6513,9 +6532,15 @@ schedule_out_process(ErtsRunQueue *c_rq, erts_aint32_t state, Process *p,
erts_smp_runq_lock(c_rq);
- return 1;
+ /*
+ * Decrement refc if process is scheduled out by a
+ * dirty scheduler, and we have not just scheduled
+ * the process using the ordinary process struct
+ * on a dirty run-queue again...
+ */
+ return !is_normal_sched && (sched_p != p
+ || !ERTS_RUNQ_IX_IS_DIRTY(runq->ix));
}
-
}
static ERTS_INLINE void
@@ -6530,8 +6555,17 @@ add2runq(int enqueue, erts_aint32_t prio,
if (runq) {
Process *sched_p;
- if (enqueue > 0)
+ if (enqueue > 0) {
sched_p = proc;
+ /*
+ * Refc on process struct (i.e. true struct,
+ * not proxy-struct) increased while in a
+ * dirty run-queue or executing on a dirty
+ * scheduler.
+ */
+ if (ERTS_RUNQ_IX_IS_DIRTY(runq->ix))
+ erts_proc_inc_refc(proc);
+ }
else {
Process *pxy;
@@ -9587,40 +9621,45 @@ Process *erts_schedule(ErtsSchedulerData *esdp, Process *p, int calls)
esdp->reductions += reds;
- /* schedule_out_process() returns with rq locked! */
- schedule_out_process(rq, state, p, proxy_p, is_normal_sched);
- proxy_p = NULL;
+ {
+ int dec_refc;
- ERTS_PROC_REDUCTIONS_EXECUTED(esdp, rq,
- (int) ERTS_PSFLGS_GET_USR_PRIO(state),
- reds,
- actual_reds);
+ /* schedule_out_process() returns with rq locked! */
+ dec_refc = schedule_out_process(rq, state, p,
+ proxy_p, is_normal_sched);
+ proxy_p = NULL;
- esdp->current_process = NULL;
+ ERTS_PROC_REDUCTIONS_EXECUTED(esdp, rq,
+ (int) ERTS_PSFLGS_GET_USR_PRIO(state),
+ reds,
+ actual_reds);
+
+ esdp->current_process = NULL;
#ifdef ERTS_SMP
- p->scheduler_data = NULL;
+ p->scheduler_data = NULL;
#endif
- erts_smp_proc_unlock(p, (ERTS_PROC_LOCK_MAIN
- | ERTS_PROC_LOCK_STATUS
- | ERTS_PROC_LOCK_TRACE));
+ erts_smp_proc_unlock(p, (ERTS_PROC_LOCK_MAIN
+ | ERTS_PROC_LOCK_STATUS
+ | ERTS_PROC_LOCK_TRACE));
- ERTS_MSACC_SET_STATE_CACHED_M(ERTS_MSACC_STATE_OTHER);
+ ERTS_MSACC_SET_STATE_CACHED_M(ERTS_MSACC_STATE_OTHER);
- if (state & ERTS_PSFLG_FREE) {
- if (!is_normal_sched) {
- ASSERT(p->flags & F_DELAYED_DEL_PROC);
- erts_proc_dec_refc(p);
- }
- else {
#ifdef ERTS_SMP
- ASSERT(esdp->free_process == p);
- esdp->free_process = NULL;
-#else
- erts_proc_dec_refc(p);
+ if (state & ERTS_PSFLG_FREE) {
+ if (!is_normal_sched) {
+ ASSERT(p->flags & F_DELAYED_DEL_PROC);
+ }
+ else {
+ ASSERT(esdp->free_process == p);
+ esdp->free_process = NULL;
+ }
+ }
#endif
- }
- }
+
+ if (dec_refc)
+ erts_proc_dec_refc(p);
+ }
#ifdef ERTS_SMP
ASSERT(!esdp->free_process);
@@ -9896,8 +9935,12 @@ Process *erts_schedule(ErtsSchedulerData *esdp, Process *p, int calls)
if (!(state & ERTS_PSFLG_PROXY))
psflg_band_mask &= ~ERTS_PSFLG_IN_RUNQ;
else {
+ Eterm pid = p->common.id;
proxy_p = p;
- p = erts_proc_lookup_raw(proxy_p->common.id);
+ p = (is_normal_sched
+ ? erts_proc_lookup_raw(pid)
+ : erts_pid2proc_opt(NULL, 0, pid, 0,
+ ERTS_P2P_FLG_INC_REFC));
if (!p) {
free_proxy_proc(proxy_p);
proxy_p = NULL;
@@ -9929,6 +9972,7 @@ Process *erts_schedule(ErtsSchedulerData *esdp, Process *p, int calls)
| ERTS_PSFLG_FREE)))
#ifdef ERTS_DIRTY_SCHEDULERS
| (((state & (ERTS_PSFLG_RUNNING
+
| ERTS_PSFLG_FREE
| ERTS_PSFLG_RUNNING_SYS
| ERTS_PSFLG_EXITING))
@@ -9961,6 +10005,8 @@ Process *erts_schedule(ErtsSchedulerData *esdp, Process *p, int calls)
/* free and not queued by proxy */
erts_proc_dec_refc(p);
}
+ if (!is_normal_sched)
+ erts_proc_dec_refc(p);
goto pick_next_process;
}
state = new;
@@ -13091,15 +13137,14 @@ erts_continue_exit_process(Process *p)
}
#ifdef ERTS_DIRTY_SCHEDULERS
- if (a & (ERTS_PSFLG_DIRTY_RUNNING
- | ERTS_PSFLG_DIRTY_RUNNING_SYS)) {
+ if (a & (ERTS_PSFLG_DIRTY_RUNNING
+ | ERTS_PSFLG_DIRTY_RUNNING_SYS)) {
p->flags |= F_DELAYED_DEL_PROC;
delay_del_proc = 1;
/*
- * The dirty scheduler will also decrease
- * refc when done...
+ * The dirty scheduler decrease refc
+ * when done with the process...
*/
- erts_proc_inc_refc(p);
}
#endif