Re: [PATCH v5 2/3] binder: add trace at free transaction.

Todd Kjos
2020-07-20T18:24:12Z

On Wed, Jun 10, 2020 at 5:24 AM Frankie Chang
<Frankie.Chang@mediatek.com> wrote:
>
> From: "Frankie.Chang" <Frankie.Chang@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.Chang@mediatek.com>
> ---
> drivers/android/binder.c | 2 ++
> drivers/android/binder_trace.h | 27 +++++++++++++++++++++++++++
> 2 files changed, 29 insertions(+)
>
> diff --git a/drivers/android/binder.c b/drivers/android/binder.c
> index 1592396..5ec9af8 100644
> --- a/drivers/android/binder.c
> +++ b/drivers/android/binder.c
> @@ -1523,6 +1523,7 @@ static void binder_free_transaction(struct binder_transaction *t)
> * If the transaction has no target_proc, then
> * t->buffer->transaction has already been cleared.
> */
> + trace_binder_txn_latency_free(t);
> binder_free_txn_fixups(t);
> kfree(t);
> binder_stats_deleted(BINDER_STAT_TRANSACTION);
> @@ -3094,6 +3095,7 @@ static void binder_transaction(struct binder_proc *proc,
> kfree(tcomplete);
> binder_stats_deleted(BINDER_STAT_TRANSACTION_COMPLETE);
> err_alloc_tcomplete_failed:
> + trace_binder_txn_latency_free(t);
> 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;

t->to_proc and t->to_thread are not safe to dereference without
holding t->lock. If the target process dies, these fields can be set
to NULL

> + __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