On Mon, 2020-08-03 at 08:12 -0700, Todd Kjos wrote: > On Sun, Aug 2, 2020 at 8:11 PM Frankie Chang <frankie.ch...@mediatek.com> > wrote: > > > > On Fri, 2020-07-31 at 11:50 -0700, Todd Kjos wrote: > > > On Mon, Jul 27, 2020 at 8:28 PM Frankie Chang > > > <frankie.ch...@mediatek.com> wrote: > > > > > > > > From: "Frankie.Chang" <frankie.ch...@mediatek.com> > > > > > > > > Since the original trace_binder_transaction_received cannot > > > > precisely present the real finished time of transaction, adding a > > > > trace_binder_txn_latency_free at the point of free transaction > > > > may be more close to it. > > > > > > > > Signed-off-by: Frankie.Chang <frankie.ch...@mediatek.com> > > > > --- > > > > drivers/android/binder.c | 6 ++++++ > > > > drivers/android/binder_trace.h | 27 +++++++++++++++++++++++++++ > > > > 2 files changed, 33 insertions(+) > > > > > > > > diff --git a/drivers/android/binder.c b/drivers/android/binder.c > > > > index 2df146f..1e6fc40 100644 > > > > --- a/drivers/android/binder.c > > > > +++ b/drivers/android/binder.c > > > > @@ -1522,6 +1522,9 @@ static void binder_free_transaction(struct > > > > binder_transaction *t) > > > > * If the transaction has no target_proc, then > > > > * t->buffer->transaction has already been cleared. > > > > */ > > > > + spin_lock(&t->lock); > > > > + trace_binder_txn_latency_free(t); > > > > + spin_unlock(&t->lock); > > > > > > Hmm. I don't prefer taking the lock just to call a trace. It doesn't > > > make clear why the lock has to be taken. I'd prefer something like: > > > > > > if (trace_binder_txn_latency_free_enabled()) { > > c > > > } > > > > > > And then the trace would use the passed-in values instead of accessing > > > via t->to_proc/to_thread. > > > > > Then we still add lock protection in the hook function, when trace is > > disable ? > > I don't understand... in the example I gave, the trace doesn't get > called if disabled. What do you mean to "add lock protection when the > trace is disabled()"? > > > > > Or we also pass these to hook function, no matter the trace is enable or > > What do you mean by "hook" function? If something has attached to the > trace, then xxx_enabled() will return true. > I'm sorry for that I misunderstand this XXX_enabled().
> > not.I think this way is more clear that the lock protects @from, > > @to_proc and @to_thread.Then, there is no need to add the lock in hook > > function. > > Why is it clearer (other than the fact that I missed including t->from > under the lock)? > I think your example is clear enough. > > > > int from_proc, from_thread, to_proc, to_thread; > > > > spin_lock(&t->lock); > > from_proc = t->from ? t->from->proc->pid : 0; > > from_thread = t->from ? t->from->pid :0; > > to_proc = t->to_proc ? t->to_proc->pid : 0; > > to_thread = t->to_thread ? t->to_thread->pid : 0; > > spin_unlock(&t->lock); > > trace_binder_txn_latency_free(t, from_proc, from_thread, to_proc, > > to_pid); > > The main feedback is I'd like to see the fields dereferenced in the > same context as the lock acquisition instead of acquiring the lock and > calling the trace function, so this code would be fine. There will be > very little contention for t->lock so using xxx_enabled() is optional. > > Since trace_binder_txn_latency_free() is called twice, it would make > sense to have a helper function to do the above. > Okay, I will make a helper function to do this in next version patch. Very thanks for your help for this. > > > > > > binder_free_txn_fixups(t); > > > > kfree(t); > > > > binder_stats_deleted(BINDER_STAT_TRANSACTION); > > > > @@ -3093,6 +3096,9 @@ static void binder_transaction(struct binder_proc > > > > *proc, > > > > kfree(tcomplete); > > > > binder_stats_deleted(BINDER_STAT_TRANSACTION_COMPLETE); > > > > err_alloc_tcomplete_failed: > > > > + spin_lock(&t->lock); > > > > + trace_binder_txn_latency_free(t); > > > > + spin_unlock(&t->lock); > > > > kfree(t); > > > > binder_stats_deleted(BINDER_STAT_TRANSACTION); > > > > err_alloc_t_failed: > > > > diff --git a/drivers/android/binder_trace.h > > > > b/drivers/android/binder_trace.h > > > > index 6731c3c..8ac87d1 100644 > > > > --- a/drivers/android/binder_trace.h > > > > +++ b/drivers/android/binder_trace.h > > > > @@ -95,6 +95,33 @@ > > > > __entry->thread_todo) > > > > ); > > > > > > > > +TRACE_EVENT(binder_txn_latency_free, > > > > + TP_PROTO(struct binder_transaction *t), > > > > + TP_ARGS(t), > > > > + TP_STRUCT__entry( > > > > + __field(int, debug_id) > > > > + __field(int, from_proc) > > > > + __field(int, from_thread) > > > > + __field(int, to_proc) > > > > + __field(int, to_thread) > > > > + __field(unsigned int, code) > > > > + __field(unsigned int, flags) > > > > + ), > > > > + TP_fast_assign( > > > > + __entry->debug_id = t->debug_id; > > > > + __entry->from_proc = t->from ? t->from->proc->pid : 0; > > > > + __entry->from_thread = t->from ? t->from->pid : 0; > > > > + __entry->to_proc = t->to_proc ? t->to_proc->pid : 0; > > > > + __entry->to_thread = t->to_thread ? t->to_thread->pid : > > > > 0; > > > > + __entry->code = t->code; > > > > + __entry->flags = t->flags; > > > > + ), > > > > + TP_printk("transaction=%d from %d:%d to %d:%d flags=0x%x > > > > code=0x%x", > > > > + __entry->debug_id, __entry->from_proc, > > > > __entry->from_thread, > > > > + __entry->to_proc, __entry->to_thread, __entry->code, > > > > + __entry->flags) > > > > +); > > > > + > > > > TRACE_EVENT(binder_transaction, > > > > TP_PROTO(bool reply, struct binder_transaction *t, > > > > struct binder_node *target_node), > > > > -- > > > > 1.7.9.5 > >