Re: [PATCH v2 dwarves 3/5] btf_encoder: rework btf_encoders__*() API to allow traversal of encoders

[Arnaldo Carvalho de Melo <acme@kernel.org>]

Em Mon, Jan 30, 2023 at 11:04:20PM +0100, Jiri Olsa escreveu:
> On Mon, Jan 30, 2023 at 02:29:43PM +0000, Alan Maguire wrote:
> > To coordinate across multiple encoders at collection time, there
> > will be a need to access the set of encoders.  Rework the unused
> > btf_encoders__*() API to facilitate this.
> > 
> > Signed-off-by: Alan Maguire <alan.maguire@oracle.com>
> > ---
> >  btf_encoder.c | 30 ++++++++++++++++++++++--------
> >  btf_encoder.h |  6 ------
> >  2 files changed, 22 insertions(+), 14 deletions(-)
> > 
> > diff --git a/btf_encoder.c b/btf_encoder.c
> > index 44f1905..e20b628 100644
> > --- a/btf_encoder.c
> > +++ b/btf_encoder.c
> > @@ -30,6 +30,7 @@
> >  
> >  #include <errno.h>
> >  #include <stdint.h>
> > +#include <pthread.h>
> >  
> >  struct elf_function {
> >  	const char	*name;
> > @@ -79,21 +80,32 @@ struct btf_encoder {
> >  	} functions;
> >  };
> >  
> > -void btf_encoders__add(struct list_head *encoders, struct btf_encoder *encoder)
> > -{
> > -	list_add_tail(&encoder->node, encoders);
> > -}
> > +static LIST_HEAD(encoders);
> > +static pthread_mutex_t encoders__lock = PTHREAD_MUTEX_INITIALIZER;
> >  
> > -struct btf_encoder *btf_encoders__first(struct list_head *encoders)
> > +/* mutex only needed for add/delete, as this can happen in multiple encoding
> > + * threads.  Traversal of the list is currently confined to thread collection.
> > + */
> > +static void btf_encoders__add(struct btf_encoder *encoder)
> >  {
> > -	return list_first_entry(encoders, struct btf_encoder, node);
> > +	pthread_mutex_lock(&encoders__lock);
> > +	list_add_tail(&encoder->node, &encoders);
> > +	pthread_mutex_unlock(&encoders__lock);
> >  }
> >  
> > -struct btf_encoder *btf_encoders__next(struct btf_encoder *encoder)
> > +#define btf_encoders__for_each_encoder(encoder)		\
> > +	list_for_each_entry(encoder, &encoders, node)
> > +
> > +static void btf_encoders__delete(struct btf_encoder *encoder)
> >  {
> > -	return list_next_entry(encoder, node);
> > +	pthread_mutex_lock(&encoders__lock);
> > +	list_del(&encoder->node);
> > +	pthread_mutex_unlock(&encoders__lock);
> >  }
> >  
> > +#define btf_encoders__for_each_encoder(encoder)			\
> > +	list_for_each_entry(encoder, &encoders, node)
> > +
> 
> there's extra btf_encoders__for_each_encoder define
> 
> hum I'm scratching my head how this compile, probably because it's identical

I removed it, thanks!

- Arnaldo
 
> jirka
> 
> 
> >  #define PERCPU_SECTION ".data..percpu"
> >  
> >  /*
> > @@ -1505,6 +1517,7 @@ struct btf_encoder *btf_encoder__new(struct cu *cu, const char *detached_filenam
> >  
> >  		if (encoder->verbose)
> >  			printf("File %s:\n", cu->filename);
> > +		btf_encoders__add(encoder);
> >  	}
> >  out:
> >  	return encoder;
> > @@ -1519,6 +1532,7 @@ void btf_encoder__delete(struct btf_encoder *encoder)
> >  	if (encoder == NULL)
> >  		return;
> >  
> > +	btf_encoders__delete(encoder);
> >  	__gobuffer__delete(&encoder->percpu_secinfo);
> >  	zfree(&encoder->filename);
> >  	btf__free(encoder->btf);
> > diff --git a/btf_encoder.h b/btf_encoder.h
> > index a65120c..34516bb 100644
> > --- a/btf_encoder.h
> > +++ b/btf_encoder.h
> > @@ -23,12 +23,6 @@ int btf_encoder__encode(struct btf_encoder *encoder);
> >  
> >  int btf_encoder__encode_cu(struct btf_encoder *encoder, struct cu *cu, struct conf_load *conf_load);
> >  
> > -void btf_encoders__add(struct list_head *encoders, struct btf_encoder *encoder);
> > -
> > -struct btf_encoder *btf_encoders__first(struct list_head *encoders);
> > -
> > -struct btf_encoder *btf_encoders__next(struct btf_encoder *encoder);
> > -
> >  struct btf *btf_encoder__btf(struct btf_encoder *encoder);
> >  
> >  int btf_encoder__add_encoder(struct btf_encoder *encoder, struct btf_encoder *other);
> > -- 
> > 1.8.3.1
> > 

-- 

- Arnaldo