[ltt-dev] [PATCH 05/13] read basic type from ltt-relay buffer

[compudj@krystal.dyndns.org (Mathieu Desnoyers)]

* Lai Jiangshan (laijs at cn.fujitsu.com) wrote:
> 
> we need function read the base type from ltt-relay buffer
> in the kernel for text output
> 
> Signed-off-by: Lai Jiangshan <laijs at cn.fujitsu.com>
> ---
>  ltt-serialize.c |   71 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 71 insertions(+)
> diff --git a/ltt/ltt-serialize.c b/ltt/ltt-serialize.c
> index 5c34899..deb9106 100644
> --- a/ltt/ltt-serialize.c
> +++ b/ltt/ltt-serialize.c
> @@ -531,6 +538,77 @@
>  }
>  EXPORT_SYMBOL_GPL(ltt_serialize_data);
>  
> +static inline u64 serialize_read_base_type(struct rchan_buf *buf, size_t *ppos,

Maybe the name "unserialize" would be more appropriate ?

> +		char trace_size, enum ltt_type trace_type)
> +{
> +	union {
> +		uint8_t  u_8;
> +		uint16_t u_16;
> +		uint32_t u_32;
> +		uint64_t u_64;
> +		int8_t   s_8;
> +		int16_t  s_16;
> +		int32_t  s_32;
> +		int64_t  s_64;
> +	} tmp;
> +	uint64_t value;
> +
> +	if (ltt_get_alignment())

This if () is unneeded. It's already in the ltt_align logic.

> +		*ppos += ltt_align(*ppos, trace_size);
> +
> +	switch (trace_type) {
> +	case LTT_TYPE_SIGNED_INT:
> +		switch (trace_size) {
> +		case 1:
> +			ltt_relay_read(buf, *ppos, &tmp.s_8, trace_size);
> +			value = tmp.s_8;

I think we could separate that in two parts to make the code smaller :

1 - 
ltt_relay_read for u8, u16, u32, u64 (not caring about singedness)

2 - depending on the sign, cast to (s8, s16, s32) and then cast to a
64-bit signed value. Or if it was already 64-bits, no conversion is
needed.

The end result (64-bit signed or unsigned value) should in the end be
casted to a u64.

Mathieu


> +			break;
> +		case 2:
> +			ltt_relay_read(buf, *ppos, &tmp.s_16, trace_size);
> +			value = tmp.s_16;
> +			break;
> +		case 4:
> +			ltt_relay_read(buf, *ppos, &tmp.s_32, trace_size);
> +			value = tmp.s_32;
> +			break;
> +		case 8:
> +			ltt_relay_read(buf, *ppos, &tmp.s_64, trace_size);
> +			value = tmp.s_64;
> +			break;
> +		default:
> +			BUG();
> +		}
> +		break;
> +	case LTT_TYPE_UNSIGNED_INT:
> +		switch (trace_size) {
> +		case 1:
> +			ltt_relay_read(buf, *ppos, &tmp.u_8, trace_size);
> +			value = tmp.u_8;
> +			break;
> +		case 2:
> +			ltt_relay_read(buf, *ppos, &tmp.u_16, trace_size);
> +			value = tmp.u_16;
> +			break;
> +		case 4:
> +			ltt_relay_read(buf, *ppos, &tmp.u_32, trace_size);
> +			value = tmp.u_32;
> +			break;
> +		case 8:
> +			ltt_relay_read(buf, *ppos, &tmp.u_64, trace_size);
> +			value = tmp.u_64;
> +			break;
> +		default:
> +			BUG();
> +		}
> +		break;
> +	default:
> +		BUG();
> +	}
> +
> +	*ppos += trace_size;
> +	return value;
> +}
> +
>  /*
>   * Calculate data size
>   * Assume that the padding for alignment starts at a sizeof(void *) address.
> 
> 
> 
> 
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-- 
Mathieu Desnoyers
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