[ltt-dev] [PATCH take2 03/13] read event header from ltt-relay buffer

[Mathieu Desnoyers]

* Lai Jiangshan (laijs at cn.fujitsu.com) wrote:
> we implement ltt_read_event_header() read event header from ltt-relay
> buffer. it does the work oppositely to ltt_write_event_header().
> 

This patch is ready, I'm merging it. Thanks !

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers at polymtl.ca>

> Signed-off-by: Lai Jiangshan <laijs at cn.fujitsu.com>
> ---
> diff --git a/include/linux/ltt-tracer.h b/include/linux/ltt-tracer.h
> index ef91456..42fc47d 100644
> --- a/include/linux/ltt-tracer.h
> +++ b/include/linux/ltt-tracer.h
> @@ -290,6 +290,8 @@ struct ltt_event_header {
>  #define	LTT_RFLAG_ID_SIZE		(1 << 1)
>  #define	LTT_RFLAG_ID_SIZE_TSC		(1 << 2)
>  
> +#define LTT_MAX_SMALL_SIZE		0xFFFFU
> +
>  /*
>   * We use asm/timex.h : cpu_khz/HZ variable in here : we might have to deal
>   * specifically with CPU frequency scaling someday, so using an interpolation
> @@ -359,7 +361,8 @@ static inline size_t ltt_subbuffer_header_size(void)
>   * Alignment of header struct on 32 bits (min arch size, header size)
>   * + sizeof(header struct)  (32-bits)
>   * + (opt) u16 (ext. event id)
> - * + (opt) u16 (event_size) (if event_size == 0xFFFFUL, has ext. event size)
> + * + (opt) u16 (event_size)
> + *             (if event_size == LTT_MAX_SMALL_SIZE, has ext. event size)
>   * + (opt) u32 (ext. event size)
>   * + (opt) u64 full TSC (aligned on min(64-bits, arch size))
>   *
> @@ -385,14 +388,14 @@ static inline unsigned char ltt_get_header_size(
>  	switch (rflags) {
>  	case LTT_RFLAG_ID_SIZE_TSC:
>  		offset += sizeof(u16) + sizeof(u16);
> -		if (data_size >= 0xFFFFU)
> +		if (data_size >= LTT_MAX_SMALL_SIZE)
>  			offset += sizeof(u32);
>  		offset += ltt_align(offset, sizeof(u64));
>  		offset += sizeof(u64);
>  		break;
>  	case LTT_RFLAG_ID_SIZE:
>  		offset += sizeof(u16) + sizeof(u16);
> -		if (data_size >= 0xFFFFU)
> +		if (data_size >= LTT_MAX_SMALL_SIZE)
>  			offset += sizeof(u32);
>  		break;
>  	case LTT_RFLAG_ID:
> @@ -449,14 +452,14 @@ static inline size_t ltt_write_event_header(struct ltt_trace_struct *trace,
>  
>  	switch (rflags) {
>  	case LTT_RFLAG_ID_SIZE_TSC:
> -		small_size = min_t(size_t, event_size, 0xFFFFU);
> +		small_size = min_t(size_t, event_size, LTT_MAX_SMALL_SIZE);
>  		ltt_relay_write(buf, buf_offset,
>  			(u16[]){ (u16)eID }, sizeof(u16));
>  		buf_offset += sizeof(u16);
>  		ltt_relay_write(buf, buf_offset,
>  			(u16[]){ (u16)small_size }, sizeof(u16));
>  		buf_offset += sizeof(u16);
> -		if (small_size == 0xFFFFU) {
> +		if (small_size == LTT_MAX_SMALL_SIZE) {
>  			ltt_relay_write(buf, buf_offset,
>  				(u32[]){ (u32)event_size }, sizeof(u32));
>  			buf_offset += sizeof(u32);
> @@ -467,14 +470,14 @@ static inline size_t ltt_write_event_header(struct ltt_trace_struct *trace,
>  		buf_offset += sizeof(u64);
>  		break;
>  	case LTT_RFLAG_ID_SIZE:
> -		small_size = min_t(size_t, event_size, 0xFFFFU);
> +		small_size = min_t(size_t, event_size, LTT_MAX_SMALL_SIZE);
>  		ltt_relay_write(buf, buf_offset,
>  			(u16[]){ (u16)eID }, sizeof(u16));
>  		buf_offset += sizeof(u16);
>  		ltt_relay_write(buf, buf_offset,
>  			(u16[]){ (u16)small_size }, sizeof(u16));
>  		buf_offset += sizeof(u16);
> -		if (small_size == 0xFFFFU) {
> +		if (small_size == LTT_MAX_SMALL_SIZE) {
>  			ltt_relay_write(buf, buf_offset,
>  				(u32[]){ (u32)event_size }, sizeof(u32));
>  			buf_offset += sizeof(u32);
> @@ -492,6 +495,67 @@ static inline size_t ltt_write_event_header(struct ltt_trace_struct *trace,
>  	return buf_offset;
>  }
>  
> +/*
> + * ltt_read_event_header
> + * buf_offset must aligned on 32 bits
> + */
> +static inline size_t ltt_read_event_header(struct rchan_buf *buf,
> +		long buf_offset, u64 *tsc, u32 *event_size, u16 *eID,
> +		unsigned int *rflags)
> +{
> +	struct ltt_event_header header;
> +	u16 small_size;
> +
> +	ltt_relay_read(buf, buf_offset, &header, sizeof(header));
> +	buf_offset += sizeof(header);
> +
> +	*event_size = INT_MAX;
> +	*eID = header.id_time >> LTT_TSC_BITS;
> +	*tsc = header.id_time & LTT_TSC_MASK;
> +
> +	switch (*eID) {
> +	case 29:
> +		*rflags = LTT_RFLAG_ID_SIZE_TSC;
> +		ltt_relay_read(buf, buf_offset, eID, sizeof(u16));
> +		buf_offset += sizeof(u16);
> +		ltt_relay_read(buf, buf_offset, &small_size, sizeof(u16));
> +		buf_offset += sizeof(u16);
> +		if (small_size == LTT_MAX_SMALL_SIZE) {
> +			ltt_relay_read(buf, buf_offset, event_size,
> +					sizeof(u32));
> +			buf_offset += sizeof(u32);
> +		} else
> +			*event_size = small_size;
> +		buf_offset += ltt_align(buf_offset, sizeof(u64));
> +		ltt_relay_read(buf, buf_offset, tsc, sizeof(u64));
> +		buf_offset += sizeof(u64);
> +		break;
> +	case 30:
> +		*rflags = LTT_RFLAG_ID_SIZE;
> +		ltt_relay_read(buf, buf_offset, eID, sizeof(u16));
> +		buf_offset += sizeof(u16);
> +		ltt_relay_read(buf, buf_offset, &small_size, sizeof(u16));
> +		buf_offset += sizeof(u16);
> +		if (small_size == LTT_MAX_SMALL_SIZE) {
> +			ltt_relay_read(buf, buf_offset, event_size,
> +					sizeof(u32));
> +			buf_offset += sizeof(u32);
> +		} else
> +			*event_size = small_size;
> +		break;
> +	case 31:
> +		*rflags = LTT_RFLAG_ID;
> +		ltt_relay_read(buf, buf_offset, eID, sizeof(u16));
> +		buf_offset += sizeof(u16);
> +		break;
> +	default:
> +		*rflags = 0;
> +		break;
> +	}
> +
> +	return buf_offset;
> +}
> +
>  /* Lockless LTTng */
>  
>  /* Buffer offset macros */
> 
> 
> 
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> 

-- 
Mathieu Desnoyers
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