On 2021/02/25 16:03, Chaitanya Kulkarni wrote:
> Signed-off-by: Chaitanya Kulkarni <chaitanya.kulkarni@xxxxxxx>
No commit message. Please add one.
> ---
> kernel/trace/blktrace.c | 130 ++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 130 insertions(+)
>
> diff --git a/kernel/trace/blktrace.c b/kernel/trace/blktrace.c
> index feb823b917ec..1aef55fdefa9 100644
> --- a/kernel/trace/blktrace.c
> +++ b/kernel/trace/blktrace.c
> @@ -462,6 +462,136 @@ static void __blk_add_trace(struct blk_trace *bt, sector_t sector, int bytes,
> local_irq_restore(flags);
> }
>
> +/*
> + * Data direction bit lookup
> + */
> +static const u64 ddir_act_ext[2] = { BLK_TC_ACT_EXT(BLK_TC_READ),
> + BLK_TC_ACT_EXT(BLK_TC_WRITE) };
> +
> +/* The ilog2() calls fall out because they're constant */
> +#define MASK_TC_BIT_EXT(rw, __name) ((rw & REQ_ ## __name) << \
> + (ilog2(BLK_TC_ ## __name) + BLK_TC_SHIFT_EXT - __REQ_ ## __name))
> +
> +/*
> + * The worker for the various blk_add_trace*() types. Fills out a
> + * blk_io_trace structure and places it in a per-cpu subbuffer.
> + */
The comment is wrong. You are filling a blk_io_trace_ext structure. But I do not
see why that structure is needed in the first place. So the function below may
not be needed either. Modifying the existing one seems like a simpler approach
to me.
> +static void __blk_add_trace_ext(struct blk_trace_ext *bt, sector_t sector, int bytes,
> + int op, int op_flags, u64 what, int error, int pdu_len,
> + void *pdu_data, u64 cgid, u32 ioprio)
> +{
> + struct task_struct *tsk = current;
> + struct ring_buffer_event *event = NULL;
> + struct trace_buffer *buffer = NULL;
> + struct blk_io_trace_ext *t;
> + unsigned long flags = 0;
> + unsigned long *sequence;
> + pid_t pid;
> + int cpu, pc = 0;
> + bool blk_tracer = blk_tracer_enabled;
> + ssize_t cgid_len = cgid ? sizeof(cgid) : 0;
> +
> + if (unlikely(bt->trace_state != Blktrace_running && !blk_tracer))
> + return;
> +
> + what |= ddir_act_ext[op_is_write(op) ? WRITE : READ];
> + what |= MASK_TC_BIT_EXT(op_flags, SYNC);
> + what |= MASK_TC_BIT_EXT(op_flags, RAHEAD);
> + what |= MASK_TC_BIT_EXT(op_flags, META);
> + what |= MASK_TC_BIT_EXT(op_flags, PREFLUSH);
> + what |= MASK_TC_BIT_EXT(op_flags, FUA);
> + if (op == REQ_OP_ZONE_APPEND)
> + what |= BLK_TC_ACT_EXT(BLK_TC_ZONE_APPEND);
> + if (op == REQ_OP_DISCARD || op == REQ_OP_SECURE_ERASE)
> + what |= BLK_TC_ACT_EXT(BLK_TC_DISCARD);
> + if (op == REQ_OP_FLUSH)
> + what |= BLK_TC_ACT_EXT(BLK_TC_FLUSH);
> + if (unlikely(op == REQ_OP_WRITE_ZEROES))
> + what |= BLK_TC_ACT_EXT(BLK_TC_WRITE_ZEROES);
> + if (unlikely(op == REQ_OP_ZONE_RESET))
> + what |= BLK_TC_ACT_EXT(BLK_TC_ZONE_RESET);
> + if (unlikely(op == REQ_OP_ZONE_RESET_ALL))
> + what |= BLK_TC_ACT_EXT(BLK_TC_ZONE_RESET_ALL);
> + if (unlikely(op == REQ_OP_ZONE_OPEN))
> + what |= BLK_TC_ACT_EXT(BLK_TC_ZONE_OPEN);
> + if (unlikely(op == REQ_OP_ZONE_CLOSE))
> + what |= BLK_TC_ACT_EXT(BLK_TC_ZONE_CLOSE);
> + if (unlikely(op == REQ_OP_ZONE_FINISH))
> + what |= BLK_TC_ACT_EXT(BLK_TC_ZONE_FINISH);
> +
> + if (cgid)
> + what |= __BLK_TA_CGROUP;
> +
> + pid = tsk->pid;
> + if (act_log_check_ext(bt, what, sector, pid))
> + return;
> + if (bt->prio_mask && !prio_log_check(bt, ioprio))
> + return;
> +
> + cpu = raw_smp_processor_id();
> +
> + if (blk_tracer) {
> + tracing_record_cmdline(current);
> +
> + buffer = blk_tr->array_buffer.buffer;
> + pc = preempt_count();
> + event = trace_buffer_lock_reserve(buffer, TRACE_BLK,
> + sizeof(*t) + pdu_len + cgid_len,
> + 0, pc);
> + if (!event)
> + return;
> + t = ring_buffer_event_data(event);
> + goto record_it;
> + }
> +
> + if (unlikely(tsk->btrace_seq != blktrace_seq))
> + trace_note_tsk_ext(tsk, ioprio);
> +
> + /*
> + * A word about the locking here - we disable interrupts to reserve
> + * some space in the relay per-cpu buffer, to prevent an irq
> + * from coming in and stepping on our toes.
> + */
> + local_irq_save(flags);
> + t = relay_reserve(bt->rchan, sizeof(*t) + pdu_len + cgid_len);
> + if (t) {
> + sequence = per_cpu_ptr(bt->sequence, cpu);
> +
> + t->magic = BLK_IO_TRACE_MAGIC | BLK_IO_TRACE_VERSION_EXT;
> + t->sequence = ++(*sequence);
> + t->time = ktime_to_ns(ktime_get());
> +record_it:
> + /*
> + * These two are not needed in ftrace as they are in the
> + * generic trace_entry, filled by tracing_generic_entry_update,
> + * but for the trace_event->bin() synthesizer benefit we do it
> + * here too.
> + */
> + t->cpu = cpu;
> + t->pid = pid;
> +
> + t->sector = sector;
> + t->bytes = bytes;
> + t->action = what;
> + t->ioprio = ioprio;
> + t->device = bt->dev;
> + t->error = error;
> + t->pdu_len = pdu_len + cgid_len;
> +
> + if (cgid_len)
> + memcpy((void *)t + sizeof(*t), &cgid, cgid_len);
> + if (pdu_len)
> + memcpy((void *)t + sizeof(*t) + cgid_len, pdu_data, pdu_len);
> +
> + if (blk_tracer) {
> + trace_buffer_unlock_commit(blk_tr, buffer, event, 0, pc);
> + return;
> + }
> + }
> +
> + local_irq_restore(flags);
> +}
> +
> static void blk_trace_free(struct blk_trace *bt)
> {
> relay_close(bt->rchan);
>
--
Damien Le Moal
Western Digital Research
