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

[Mathieu Desnoyers]

* Lai Jiangshan (laijs at cn.fujitsu.com) wrote:
> Mathieu Desnoyers wrote:
> > * 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 :
> 
> separate it into 2 functions?
> 

Not necessarily 2 functions. Just separating it in two switch () statements
would do the job.

Mathieu

> > 
> > 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
> > 
> > 
> 
> 
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-- 
Mathieu Desnoyers
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