diff options
| -rw-r--r-- | ChangeLog | 11 | ||||
| -rw-r--r-- | runtime/ChangeLog | 11 | ||||
| -rw-r--r-- | runtime/time.c | 63 | ||||
| -rw-r--r-- | tapsets.cxx | 43 | ||||
| -rw-r--r-- | translate.cxx | 4 |
5 files changed, 92 insertions, 40 deletions
@@ -1,3 +1,14 @@ +2006-12-06 Josh Stone <joshua.i.stone@intel.com> + + PR 3623. + * tapsets.cxx (timer_derived_probe_group::emit_module_decls): Restart + the timers if we are in STARTING or RUNNING state. + (hrtimer_derived_probe_group::emit_module_decls): Ditto. + (be_derived_probe_group::emit_module_init): indicate error to the rest + of the initialization if any begin probes fail. + * translate.cxx (c_unparser::emit_module_init): Set the global error + state on an initialization error so timers know to shut down. + 2006-12-05 Frank Ch. Eigler <fche@redhat.com> PR 3648. diff --git a/runtime/ChangeLog b/runtime/ChangeLog index 95c34442..9f0c1425 100644 --- a/runtime/ChangeLog +++ b/runtime/ChangeLog @@ -1,3 +1,14 @@ +2006-12-06 Josh Stone <joshua.i.stone@intel.com> + + * time.c (stp_timer_reregister): Add a global to control whether the + gettimeofday timer should restart itself, for clean shutdown. + (__stp_time_timer_callback): Check the global. + (_stp_kill_time, _stp_init_time): Set the global. + (_stp_gettimeofday_ns): Switch to preempt_enable_no_resched. + + * time.c (__stp_time_cpufreq_callback): Use the cpu# from the notifier. + (_stp_init_time): No need to disable preemption around cpufreq init. + 2006-12-04 Martin Hunt <hunt@redhat.com> * bench2/bench.rb: Fixes for the latest runtime diff --git a/runtime/time.c b/runtime/time.c index 8d82f3d1..a6b33aa8 100644 --- a/runtime/time.c +++ b/runtime/time.c @@ -17,10 +17,9 @@ typedef struct __stp_time_t { /* * A write lock is taken by __stp_time_timer_callback() and - * __stp_time_cpufreq_callback(). The timer callback is called from a - * softIRQ, and cpufreq callback guarantees that it is not called within - * an interrupt context. Thus there should be no opportunity for a - * deadlock between writers. + * __stp_time_cpufreq_callback(). Neither writer is in interrupt context, + * and both disable interrupts before taking the lock, so there should be + * no opportunity for deadlock. * * A read lock is taken by _stp_gettimeofday_us(). There is the potential * for this to occur at any time, so there is a slim chance that this will @@ -28,8 +27,9 @@ typedef struct __stp_time_t { * read lock. However, we can limit how long we try to get the lock to * avoid a deadlock. * - * Note that seqlock is safer than rwlock because some kernels - * don't have read_trylock. + * Note that seqlock is chosen so that readers don't block writers. It's + * also important that readers can attempt a lock from _any_ context (e.g., + * NMI), and some kernels don't have read_trylock. */ seqlock_t lock; @@ -47,6 +47,9 @@ typedef struct __stp_time_t { void *stp_time = NULL; +/* Flag to tell the timer callback whether to reregister */ +int stp_timer_reregister = 0; + /* Try to estimate the number of CPU cycles in a millisecond - i.e. kHz. This * relies heavily on the accuracy of udelay. By calling udelay twice, we * attempt to account for overhead in the call. @@ -74,6 +77,7 @@ __stp_estimate_cpufreq(void) #endif } +/* The timer callback is in a softIRQ -- interrupts enabled. */ static void __stp_time_timer_callback(unsigned long val) { @@ -97,7 +101,8 @@ __stp_time_timer_callback(unsigned long val) time->base_cycles = cycles; write_sequnlock(&time->lock); - mod_timer(&time->timer, jiffies + 1); + if (likely(stp_timer_reregister)) + mod_timer(&time->timer, jiffies + 1); local_irq_restore(flags); } @@ -123,6 +128,7 @@ __stp_init_time(void *info) } #ifdef CONFIG_CPU_FREQ +/* The cpufreq callback is not in interrupt context -- interrupts enabled */ static int __stp_time_cpufreq_callback(struct notifier_block *self, unsigned long state, void *vfreqs) @@ -137,7 +143,7 @@ __stp_time_cpufreq_callback(struct notifier_block *self, case CPUFREQ_RESUMECHANGE: freqs = (struct cpufreq_freqs *)vfreqs; freq_khz = freqs->new; - time = per_cpu_ptr(stp_time, smp_processor_id()); + time = per_cpu_ptr(stp_time, freqs->cpu); write_seqlock_irqsave(&time->lock, flags); time->cpufreq = freq_khz; write_sequnlock_irqrestore(&time->lock, flags); @@ -152,11 +158,13 @@ struct notifier_block __stp_time_notifier = { }; #endif /* CONFIG_CPU_FREQ */ +/* This function is called during module unloading. */ void _stp_kill_time(void) { if (stp_time) { int cpu; + stp_timer_reregister = 0; for_each_online_cpu(cpu) { stp_time_t *time = per_cpu_ptr(stp_time, cpu); del_timer_sync(&time->timer); @@ -170,38 +178,38 @@ _stp_kill_time(void) } } +/* This function is called during module loading. */ int _stp_init_time(void) { int ret = 0; - int cpu, freq_khz; - unsigned long flags; stp_time = alloc_percpu(stp_time_t); if (unlikely(stp_time == 0)) return -1; + stp_timer_reregister = 1; ret = on_each_cpu(__stp_init_time, NULL, 0, 1); #ifdef CONFIG_CPU_FREQ - if (ret) goto end; - - ret = cpufreq_register_notifier(&__stp_time_notifier, - CPUFREQ_TRANSITION_NOTIFIER); - if (ret) goto end; - - for_each_online_cpu(cpu) { - preempt_disable(); - freq_khz = cpufreq_get(cpu); - if (freq_khz > 0) { - stp_time_t *time = per_cpu_ptr(stp_time, cpu); - write_seqlock_irqsave(&time->lock, flags); - time->cpufreq = freq_khz; - write_sequnlock_irqrestore(&time->lock, flags); + if (!ret) { + ret = cpufreq_register_notifier(&__stp_time_notifier, + CPUFREQ_TRANSITION_NOTIFIER); + + if (!ret) { + int cpu; + for_each_online_cpu(cpu) { + unsigned long flags; + int freq_khz = cpufreq_get(cpu); + if (freq_khz > 0) { + stp_time_t *time = per_cpu_ptr(stp_time, cpu); + write_seqlock_irqsave(&time->lock, flags); + time->cpufreq = freq_khz; + write_sequnlock_irqrestore(&time->lock, flags); + } + } } - preempt_enable(); } -end: #endif return ret; @@ -219,6 +227,7 @@ _stp_gettimeofday_ns(void) preempt_disable(); time = per_cpu_ptr(stp_time, smp_processor_id()); + seq = read_seqbegin(&time->lock); base = time->base_ns; last = time->base_cycles; @@ -235,7 +244,7 @@ _stp_gettimeofday_ns(void) delta = get_cycles() - last; - preempt_enable(); + preempt_enable_no_resched(); #if defined (__s390__) || defined (__s390x__) // The TOD clock on the s390 (read by get_cycles() ) diff --git a/tapsets.cxx b/tapsets.cxx index 8bce8cd8..a71b352e 100644 --- a/tapsets.cxx +++ b/tapsets.cxx @@ -285,9 +285,18 @@ void be_derived_probe_group::emit_module_init (systemtap_session& s) { // if (probes.empty()) return; + bool have_begin_probes = false; for (unsigned i=0; i < probes.size (); i++) if (probes[i]->begin) - s.op->newline() << "enter_begin_probe (& " << probes[i]->name << ");"; + { + have_begin_probes = true; + s.op->newline() << "enter_begin_probe (& " << probes[i]->name << ");"; + } + + // If any of the begin probes signaled an error, indicate + // failure to the rest of systemtap_module_init. + if (have_begin_probes) + s.op->newline() << "rc = (atomic_read (&session_state) == STAP_SESSION_ERROR);"; } void @@ -3771,14 +3780,19 @@ timer_derived_probe_group::emit_module_decls (systemtap_session& s) s.op->newline() << "static void enter_timer_probe (unsigned long val) {"; s.op->newline(1) << "struct stap_timer_probe* stp = & stap_timer_probes [val];"; - common_probe_entryfn_prologue (s.op, "STAP_SESSION_RUNNING"); - s.op->newline() << "c->probe_point = stp->pp;"; - s.op->newline() << "mod_timer (& stp->timer_list, jiffies + "; + s.op->newline() << "if ((atomic_read (&session_state) == STAP_SESSION_STARTING) ||"; + s.op->newline() << " (atomic_read (&session_state) == STAP_SESSION_RUNNING))"; + s.op->newline(1) << "mod_timer (& stp->timer_list, jiffies + "; emit_interval (s.op); s.op->line() << ");"; + s.op->newline(-1) << "{"; + s.op->indent(1); + common_probe_entryfn_prologue (s.op, "STAP_SESSION_RUNNING"); + s.op->newline() << "c->probe_point = stp->pp;"; s.op->newline() << "(*stp->ph) (c);"; common_probe_entryfn_epilogue (s.op); s.op->newline(-1) << "}"; + s.op->newline(-1) << "}"; } @@ -4576,19 +4590,24 @@ hrtimer_derived_probe_group::emit_module_decls (systemtap_session& s) s.op->newline(); s.op->newline() << "static int enter_hrtimer_probe (struct hrtimer *timer) {"; - s.op->newline(1) << "struct stap_hrtimer_probe *stp = container_of(timer, struct stap_hrtimer_probe, hrtimer);"; - // presume problem with updating ->expires or something else XXX - s.op->newline() << "int restart_or_not = HRTIMER_NORESTART;"; - common_probe_entryfn_prologue (s.op, "STAP_SESSION_RUNNING"); - s.op->newline() << "c->probe_point = stp->pp;"; + s.op->newline(1) << "int rc = HRTIMER_NORESTART;"; + s.op->newline() << "struct stap_hrtimer_probe *stp = container_of(timer, struct stap_hrtimer_probe, hrtimer);"; + s.op->newline() << "if ((atomic_read (&session_state) == STAP_SESSION_STARTING) ||"; + s.op->newline() << " (atomic_read (&session_state) == STAP_SESSION_RUNNING)) {"; // Compute next trigger time - s.op->newline() << "timer->expires = ktime_add (timer->expires,"; + s.op->newline(1) << "timer->expires = ktime_add (timer->expires,"; emit_interval (s.op); s.op->line() << ");"; - s.op->newline() << "restart_or_not = HRTIMER_RESTART;"; // ->expires updated; safe to restart + s.op->newline() << "rc = HRTIMER_RESTART;"; + s.op->newline(-1) << "}"; + s.op->newline() << "{"; + s.op->indent(1); + common_probe_entryfn_prologue (s.op, "STAP_SESSION_RUNNING"); + s.op->newline() << "c->probe_point = stp->pp;"; s.op->newline() << "(*stp->ph) (c);"; common_probe_entryfn_epilogue (s.op); - s.op->newline() << "return restart_or_not;"; + s.op->newline(-1) << "}"; + s.op->newline() << "return rc;"; s.op->newline(-1) << "}"; } diff --git a/translate.cxx b/translate.cxx index f36280da..f6214206 100644 --- a/translate.cxx +++ b/translate.cxx @@ -1083,7 +1083,9 @@ c_unparser::emit_module_init () // NB: this gives O(N**2) amount of code, but luckily there // are only seven or eight derived_probe_groups, so it's ok. o->newline() << "if (rc) {"; - o->indent(1); + // NB: we need to be in the error state so timers can shutdown cleanly, + // and so end probes don't run. + o->newline(1) << "atomic_set (&session_state, STAP_SESSION_ERROR);"; if (i>0) for (int j=i-1; j>=0; j--) g[j]->emit_module_exit (*session); |