From 32c71f85bd2d17a6c58f6d1fa450dfb8cf3de6cb Mon Sep 17 00:00:00 2001 From: Rickard Green Date: Wed, 28 Dec 2016 18:27:54 +0100 Subject: Fix premature removal of process struct Refc on process struct could reach zero while it was still referred by dirty scheduler --- erts/emulator/beam/erl_process.c | 119 +++++++++++++++++++++++++++------------ 1 file changed, 82 insertions(+), 37 deletions(-) (limited to 'erts') 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 -- cgit v1.2.3