[PATCH] dissect: use struct symbol::visited/inspected instead of ::examined/evaluated

[PATCH] dissect: use struct symbol::visited/inspected instead of ::examined/evaluated

[Luc Van Oostenryck]

The dissect client uses struct symbol's fields 'examined' & 'evaluated'
to avoid reprocessing the same symbols. But these fields are used
internally by sparse for type examination & evaluation and despite
dissect not doing these operations explicitly, they can be done
implicitly (for example to handle static assertions or when the
value of a constant expression is needed).

So, add a new field to struct symbol: 'inspected' and use it, as
well as the existing 'visited', instead of 'evaluated' & 'examined'.

Note: when used on the kernel, this patch avoids a lot of warnings:
	"warning: r_member bad sym type=7 kind=0"
	"warning: r_member bad mem->kind = 0"
      and creates substantially more normal output.

Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>
---
 dissect.c | 8 ++++----
 symbol.h  | 1 +
 2 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/dissect.c b/dissect.c
index fd09707dbf67..582e8fc32e46 100644
--- a/dissect.c
+++ b/dissect.c
@@ -204,9 +204,9 @@ static void examine_sym_node(struct symbol *node, struct symbol *parent)
 	struct ident *name = node->ident;
 	struct symbol *base, *dctx;
 
-	if (node->examined)
+	if (node->visited)
 		return;
-	node->examined = 1;
+	node->visited = 1;
 	node->kind = 'v';
 
 	while ((base = node->ctype.base_type) != NULL)
@@ -228,9 +228,9 @@ static void examine_sym_node(struct symbol *node, struct symbol *parent)
 			break;
 
 		case SYM_STRUCT: case SYM_UNION: //case SYM_ENUM:
-			if (base->evaluated)
+			if (base->inspected)
 				return;
-			base->evaluated = 1;
+			base->inspected = 1;
 			base->kind = 's';
 
 			if (!base->symbol_list)
diff --git a/symbol.h b/symbol.h
index c2b60ce91c27..08d1134a7d82 100644
--- a/symbol.h
+++ b/symbol.h
@@ -209,6 +209,7 @@ struct symbol {
 		struct {			/* sparse ctags */
 			char kind;
 			unsigned char visited:1;
+			unsigned char inspected:1;
 		};
 	};
 	pseudo_t pseudo;
-- 
2.28.0

Re: [PATCH] dissect: use struct symbol::visited/inspected instead of ::examined/evaluated

[Oleg Nesterov]

On 07/29, Luc Van Oostenryck wrote:
>
> The dissect client uses struct symbol's fields 'examined' & 'evaluated'
> to avoid reprocessing the same symbols. But these fields are used
> internally by sparse for type examination & evaluation and despite
> dissect not doing these operations explicitly, they can be done
> implicitly

Yes. For example, test_dissect.c calls show_typename() and this can
lead to examine/evaluate.

I didn't bother to fix this because test_dissect.c is the very basic
debugging tool.

> So, add a new field to struct symbol: 'inspected' and use it, as
> well as the existing 'visited', instead of 'evaluated' & 'examined'.

Thanks! Looks good to me.

> Note: when used on the kernel, this patch avoids a lot of warnings:
> 	"warning: r_member bad sym type=7 kind=0"
> 	"warning: r_member bad mem->kind = 0"
>       and creates substantially more normal output.

So this is test-dissect, sindex should be fine even without this patch.

Acked-by: Oleg Nesterov <oleg@redhat.com>

Re: [PATCH] dissect: use struct symbol::visited/inspected instead of ::examined/evaluated

[Luc Van Oostenryck]

On Wed, Jul 29, 2020 at 05:34:13PM +0200, Oleg Nesterov wrote:
> On 07/29, Luc Van Oostenryck wrote:
> >
> > The dissect client uses struct symbol's fields 'examined' & 'evaluated'
> > to avoid reprocessing the same symbols. But these fields are used
> > internally by sparse for type examination & evaluation and despite
> > dissect not doing these operations explicitly, they can be done
> > implicitly
> 
> Yes. For example, test_dissect.c calls show_typename() and this can
> lead to examine/evaluate.
> 
> I didn't bother to fix this because test_dissect.c is the very basic
> debugging tool.
> 
> > So, add a new field to struct symbol: 'inspected' and use it, as
> > well as the existing 'visited', instead of 'evaluated' & 'examined'.
> 
> Thanks! Looks good to me.
> 
> > Note: when used on the kernel, this patch avoids a lot of warnings:
> > 	"warning: r_member bad sym type=7 kind=0"
> > 	"warning: r_member bad mem->kind = 0"
> >       and creates substantially more normal output.
> 
> So this is test-dissect, sindex should be fine even without this patch.

Yes, I only used test-dissect but sindex should be affected too.
The real problem is that, even without the show_typename() from
test-dissect, some symbols can already be examined by __sparse().
In this case dissect.c:examine_sym_node() will be a no-op because
node->examined will already be set. One of the symptoms is node->kind
having a value of 0.

I'll clarify the commit message.

-- Luc