kernel-doc : possible fix for non-fatal perl errors when parsing some function pointers

kernel-doc : possible fix for non-fatal perl errors when parsing some function pointers

[Richard Kennedy]

When running "make htmldocs" I'm seeing some non-fatal perl errors
caused by trying to parse the callback function definitions in
blk-core.c.

The errors are "Use of uninitialized value in concatenation (.)..."

The function pointers are defined without a * i.e. 
int (drv_callback)(struct request *)

The compiler is happy with them, but kernel-doc isn't. 

This patch teaches create_parameterlist in kernel-doc to parse this type
of function pointer definition, but is it the right way to fix the
problem ? The problem only seems to occur in blk-core.c.

However with the patch applied, kernel-doc finds the correct parameter
description for the callback in blk_end_request_callback, which is
doesn't normally.
(the patch is against v2.6.25-rc1)

I thought it would be a bit odd to change to code to use the more normal
form of function pointers just to get the documentation to work, so I
fixed kernel-doc instead - even though this is teaching it to understand
code that might go away (The comment for blk_end_request_callback says
that it should not be used and will removed at some point). 

Any ideas on which is the best way to fix this?
 
Thanks
Richard






diff --git a/scripts/kernel-doc b/scripts/kernel-doc
index 26146cb..68b2e4e 100755
--- a/scripts/kernel-doc
+++ b/scripts/kernel-doc
@@ -1512,13 +1512,13 @@ sub create_parameterlist($$$) {
 	    # corresponding data structures "correctly". Catch it later in
 	    # output_* subs.
 	    push_parameter($arg, "", $file);
-	} elsif ($arg =~ m/\(.*\*/) {
+	} elsif ($arg =~ m/\(.+\)\s*\(/) {
 	    # pointer-to-function
 	    $arg =~ tr/#/,/;
-	    $arg =~ m/[^\(]+\(\*\s*([^\)]+)\)/;
+	    $arg =~ m/[^\(]+\(\*?\s*(\w*)\s*\)/;
 	    $param = $1;
 	    $type = $arg;
-	    $type =~ s/([^\(]+\(\*)$param/$1/;
+	    $type =~ s/([^\(]+\(\*?)$param/$1/;
 	    push_parameter($param, $type, $file);
 	} elsif ($arg) {
 	    $arg =~ s/\s*:\s*/:/g;
--  

Re: kernel-doc : possible fix for non-fatal perl errors when parsing some function pointers

[Randy Dunlap]

On Fri, 15 Feb 2008 17:13:12 +0000 Richard Kennedy wrote:

> When running "make htmldocs" I'm seeing some non-fatal perl errors
> caused by trying to parse the callback function definitions in
> blk-core.c.
> 
> The errors are "Use of uninitialized value in concatenation (.)..."
> 
> The function pointers are defined without a * i.e. 
> int (drv_callback)(struct request *)
> 
> The compiler is happy with them, but kernel-doc isn't. 
> 
> This patch teaches create_parameterlist in kernel-doc to parse this type
> of function pointer definition, but is it the right way to fix the
> problem ? The problem only seems to occur in blk-core.c.
> 
> However with the patch applied, kernel-doc finds the correct parameter
> description for the callback in blk_end_request_callback, which is
> doesn't normally.
> (the patch is against v2.6.25-rc1)
> 
> I thought it would be a bit odd to change to code to use the more normal
> form of function pointers just to get the documentation to work, so I
> fixed kernel-doc instead - even though this is teaching it to understand
> code that might go away (The comment for blk_end_request_callback says
> that it should not be used and will removed at some point). 
> 
> Any ideas on which is the best way to fix this?

Hi Richard,
Thanks for the patch.  I was planning to look into this problem
this weekend.

I think that changing scripts/kernel-doc to accept the current
kernel source tree usage is the right thing to do, even if the
block/blk code is a bit different.  I'll test it a bit and then
push it.

I appreciate the patch.

> diff --git a/scripts/kernel-doc b/scripts/kernel-doc
> index 26146cb..68b2e4e 100755
> --- a/scripts/kernel-doc
> +++ b/scripts/kernel-doc
> @@ -1512,13 +1512,13 @@ sub create_parameterlist($$$) {
>  	    # corresponding data structures "correctly". Catch it later in
>  	    # output_* subs.
>  	    push_parameter($arg, "", $file);
> -	} elsif ($arg =~ m/\(.*\*/) {
> +	} elsif ($arg =~ m/\(.+\)\s*\(/) {
>  	    # pointer-to-function
>  	    $arg =~ tr/#/,/;
> -	    $arg =~ m/[^\(]+\(\*\s*([^\)]+)\)/;
> +	    $arg =~ m/[^\(]+\(\*?\s*(\w*)\s*\)/;
>  	    $param = $1;
>  	    $type = $arg;
> -	    $type =~ s/([^\(]+\(\*)$param/$1/;
> +	    $type =~ s/([^\(]+\(\*?)$param/$1/;
>  	    push_parameter($param, $type, $file);
>  	} elsif ($arg) {
>  	    $arg =~ s/\s*:\s*/:/g;
> --  

---
~Randy

Re: kernel-doc : possible fix for non-fatal perl errors when parsing some function pointers

[Richard Kennedy]

On Fri, 2008-02-15 at 09:21 -0800, Randy Dunlap wrote:
> On Fri, 15 Feb 2008 17:13:12 +0000 Richard Kennedy wrote:
> 
> > When running "make htmldocs" I'm seeing some non-fatal perl errors
> > caused by trying to parse the callback function definitions in
> > blk-core.c.
> > 
> >
> 
> Hi Richard,
> Thanks for the patch.  I was planning to look into this problem
> this weekend.
> 
> I think that changing scripts/kernel-doc to accept the current
> kernel source tree usage is the right thing to do, even if the
> block/blk code is a bit different.  I'll test it a bit and then
> push it.
> 
> I appreciate the patch.
> 
No problem. 

I have given the patch some testing, and the output xml is the same
except for the blk_end_request_callback entry.

But I wonder if it should change to this :-

> -         $type =~ s/([^\(]+\(\*)$param/$1/;
> +         $type =~ s/([^\(]+\(\*?)\s*$param/$1/;

just in case there is some stray whitespace in there.

Richard

> ---
> ~Randy

Re: kernel-doc : possible fix for non-fatal perl errors when parsing some function pointers

[Randy Dunlap]

On Fri, 15 Feb 2008 17:42:24 +0000 Richard Kennedy wrote:

> 
> On Fri, 2008-02-15 at 09:21 -0800, Randy Dunlap wrote:
> > On Fri, 15 Feb 2008 17:13:12 +0000 Richard Kennedy wrote:
> > 
> > > When running "make htmldocs" I'm seeing some non-fatal perl errors
> > > caused by trying to parse the callback function definitions in
> > > blk-core.c.
> > > 
> > >
> > 
> > Hi Richard,
> > Thanks for the patch.  I was planning to look into this problem
> > this weekend.
> > 
> > I think that changing scripts/kernel-doc to accept the current
> > kernel source tree usage is the right thing to do, even if the
> > block/blk code is a bit different.  I'll test it a bit and then
> > push it.
> > 
> > I appreciate the patch.
> > 
> No problem. 
> 
> I have given the patch some testing, and the output xml is the same
> except for the blk_end_request_callback entry.
> 
> But I wonder if it should change to this :-
> 
> > -         $type =~ s/([^\(]+\(\*)$param/$1/;
> > +         $type =~ s/([^\(]+\(\*?)\s*$param/$1/;
> 
> just in case there is some stray whitespace in there.

That should be OK, so I changed that line.

Can I get a Signed-off-by: from you, please?

Thanks,
---
~Randy

Re: kernel-doc : possible fix for non-fatal perl errors when parsing some function pointers

[Richard Kennedy]

On Fri, 2008-02-15 at 14:46 -0800, Randy Dunlap wrote:
> On Fri, 15 Feb 2008 17:42:24 +0000 Richard Kennedy wrote:
> 
> > 
> > On Fri, 2008-02-15 at 09:21 -0800, Randy Dunlap wrote:
> > > On Fri, 15 Feb 2008 17:13:12 +0000 Richard Kennedy wrote:
> > > 
> > > > When running "make htmldocs" I'm seeing some non-fatal perl errors
> > > > caused by trying to parse the callback function definitions in
> > > > blk-core.c.
> > > > 
> > > >
> > > 
> > > Hi Richard,
> > > Thanks for the patch.  I was planning to look into this problem
> > > this weekend.
> > > 
> > > I think that changing scripts/kernel-doc to accept the current
> > > kernel source tree usage is the right thing to do, even if the
> > > block/blk code is a bit different.  I'll test it a bit and then
> > > push it.
> > > 
> > > I appreciate the patch.
> > > 
> > No problem. 
> > 
> > I have given the patch some testing, and the output xml is the same
> > except for the blk_end_request_callback entry.
> > 
> > But I wonder if it should change to this :-
> > 
> > > -         $type =~ s/([^\(]+\(\*)$param/$1/;
> > > +         $type =~ s/([^\(]+\(\*?)\s*$param/$1/;
> > 
> > just in case there is some stray whitespace in there.
> 
> That should be OK, so I changed that line.
> 
> Can I get a Signed-off-by: from you, please?
> 
> Thanks,
> ---
Signed-off-by: Richard Kennedy <richard@rsk.demon.co.uk>

Re: kernel-doc : possible fix for non-fatal perl errors when parsing some function pointers

[Randy Dunlap]

On Fri, 15 Feb 2008 09:21:54 -0800 Randy Dunlap wrote:

> On Fri, 15 Feb 2008 17:13:12 +0000 Richard Kennedy wrote:
> 
> > When running "make htmldocs" I'm seeing some non-fatal perl errors
> > caused by trying to parse the callback function definitions in
> > blk-core.c.
> > 
> > The errors are "Use of uninitialized value in concatenation (.)..."
> > 
> > The function pointers are defined without a * i.e. 
> > int (drv_callback)(struct request *)
> > 
> > The compiler is happy with them, but kernel-doc isn't. 
> > 
> > This patch teaches create_parameterlist in kernel-doc to parse this type
> > of function pointer definition, but is it the right way to fix the
> > problem ? The problem only seems to occur in blk-core.c.
> > 
> > However with the patch applied, kernel-doc finds the correct parameter
> > description for the callback in blk_end_request_callback, which is
> > doesn't normally.
> > (the patch is against v2.6.25-rc1)
> > 
> > I thought it would be a bit odd to change to code to use the more normal
> > form of function pointers just to get the documentation to work, so I
> > fixed kernel-doc instead - even though this is teaching it to understand
> > code that might go away (The comment for blk_end_request_callback says
> > that it should not be used and will removed at some point). 
> > 
> > Any ideas on which is the best way to fix this?
> 
> Hi Richard,
> Thanks for the patch.  I was planning to look into this problem
> this weekend.
> 
> I think that changing scripts/kernel-doc to accept the current
> kernel source tree usage is the right thing to do, even if the
> block/blk code is a bit different.  I'll test it a bit and then
> push it.

I'm not quite happy with the way that these function pointer
parameters are presented.  E.g.,
the callback function above is presented by kernel-doc as:

		int ()(struct request *) drv_callback);
whereas this
		int (drv_callback)(struct request *)
would be much better.  If you could look into massaging that
parameter output, that would be great.  If not, I'll look into
later.


> I appreciate the patch.
> 
> > diff --git a/scripts/kernel-doc b/scripts/kernel-doc
> > index 26146cb..68b2e4e 100755
> > --- a/scripts/kernel-doc
> > +++ b/scripts/kernel-doc
> > @@ -1512,13 +1512,13 @@ sub create_parameterlist($$$) {
> >  	    # corresponding data structures "correctly". Catch it later in
> >  	    # output_* subs.
> >  	    push_parameter($arg, "", $file);
> > -	} elsif ($arg =~ m/\(.*\*/) {
> > +	} elsif ($arg =~ m/\(.+\)\s*\(/) {
> >  	    # pointer-to-function
> >  	    $arg =~ tr/#/,/;
> > -	    $arg =~ m/[^\(]+\(\*\s*([^\)]+)\)/;
> > +	    $arg =~ m/[^\(]+\(\*?\s*(\w*)\s*\)/;
> >  	    $param = $1;
> >  	    $type = $arg;
> > -	    $type =~ s/([^\(]+\(\*)$param/$1/;
> > +	    $type =~ s/([^\(]+\(\*?)$param/$1/;
> >  	    push_parameter($param, $type, $file);
> >  	} elsif ($arg) {
> >  	    $arg =~ s/\s*:\s*/:/g;


---
~Randy

Re: kernel-doc : possible fix for non-fatal perl errors when parsing some function pointers

[Randy Dunlap]

On Fri, 15 Feb 2008 09:44:37 -0800 Randy Dunlap wrote:

> On Fri, 15 Feb 2008 09:21:54 -0800 Randy Dunlap wrote:
> 
> > On Fri, 15 Feb 2008 17:13:12 +0000 Richard Kennedy wrote:
> > 
> > > When running "make htmldocs" I'm seeing some non-fatal perl errors
> > > caused by trying to parse the callback function definitions in
> > > blk-core.c.
> > > 
> > > The errors are "Use of uninitialized value in concatenation (.)..."
> > > 
> > > The function pointers are defined without a * i.e. 
> > > int (drv_callback)(struct request *)
> > > 
> > > The compiler is happy with them, but kernel-doc isn't. 
> > > 
> > > This patch teaches create_parameterlist in kernel-doc to parse this type
> > > of function pointer definition, but is it the right way to fix the
> > > problem ? The problem only seems to occur in blk-core.c.
> > > 
> > > However with the patch applied, kernel-doc finds the correct parameter
> > > description for the callback in blk_end_request_callback, which is
> > > doesn't normally.
> > > (the patch is against v2.6.25-rc1)
> > > 
> > > I thought it would be a bit odd to change to code to use the more normal
> > > form of function pointers just to get the documentation to work, so I
> > > fixed kernel-doc instead - even though this is teaching it to understand
> > > code that might go away (The comment for blk_end_request_callback says
> > > that it should not be used and will removed at some point). 
> > > 
> > > Any ideas on which is the best way to fix this?
> > 
> > Hi Richard,
> > Thanks for the patch.  I was planning to look into this problem
> > this weekend.
> > 
> > I think that changing scripts/kernel-doc to accept the current
> > kernel source tree usage is the right thing to do, even if the
> > block/blk code is a bit different.  I'll test it a bit and then
> > push it.
> 
> I'm not quite happy with the way that these function pointer
> parameters are presented.  E.g.,
> the callback function above is presented by kernel-doc as:
> 
> 		int ()(struct request *) drv_callback);
> whereas this
> 		int (drv_callback)(struct request *)
> would be much better.  If you could look into massaging that
> parameter output, that would be great.  If not, I'll look into
> later.

OK, this is a separate issue, so your patch doesn't need to handle/fix
it.  I'll check your followup email/patch for whitespace etc....


> > I appreciate the patch.
> > 
> > > diff --git a/scripts/kernel-doc b/scripts/kernel-doc
> > > index 26146cb..68b2e4e 100755
> > > --- a/scripts/kernel-doc
> > > +++ b/scripts/kernel-doc
> > > @@ -1512,13 +1512,13 @@ sub create_parameterlist($$$) {
> > >  	    # corresponding data structures "correctly". Catch it later in
> > >  	    # output_* subs.
> > >  	    push_parameter($arg, "", $file);
> > > -	} elsif ($arg =~ m/\(.*\*/) {
> > > +	} elsif ($arg =~ m/\(.+\)\s*\(/) {
> > >  	    # pointer-to-function
> > >  	    $arg =~ tr/#/,/;
> > > -	    $arg =~ m/[^\(]+\(\*\s*([^\)]+)\)/;
> > > +	    $arg =~ m/[^\(]+\(\*?\s*(\w*)\s*\)/;
> > >  	    $param = $1;
> > >  	    $type = $arg;
> > > -	    $type =~ s/([^\(]+\(\*)$param/$1/;
> > > +	    $type =~ s/([^\(]+\(\*?)$param/$1/;
> > >  	    push_parameter($param, $type, $file);
> > >  	} elsif ($arg) {
> > >  	    $arg =~ s/\s*:\s*/:/g;

---
~Randy

Re: kernel-doc : possible fix for non-fatal perl errors when parsing some function pointers

[Richard Kennedy]

On Fri, 2008-02-15 at 09:44 -0800, Randy Dunlap wrote:
> On Fri, 15 Feb 2008 09:21:54 -0800 Randy Dunlap wrote:
> 
> > On Fri, 15 Feb 2008 17:13:12 +0000 Richard Kennedy wrote:
> > 
> > > When running "make htmldocs" I'm seeing some non-fatal perl errors
> > > caused by trying to parse the callback function definitions in
> > > blk-core.c.
> > > 
> > > The errors are "Use of uninitialized value in concatenation (.)..."
> > > 
> > > The function pointers are defined without a * i.e. 
> > > int (drv_callback)(struct request *)
> > > 
> > > The compiler is happy with them, but kernel-doc isn't. 
> > > 
> > > This patch teaches create_parameterlist in kernel-doc to parse this type
> > > of function pointer definition, but is it the right way to fix the
> > > problem ? The problem only seems to occur in blk-core.c.
> > > 
> > > However with the patch applied, kernel-doc finds the correct parameter
> > > description for the callback in blk_end_request_callback, which is
> > > doesn't normally.
> > > (the patch is against v2.6.25-rc1)
> > > 
> > > I thought it would be a bit odd to change to code to use the more normal
> > > form of function pointers just to get the documentation to work, so I
> > > fixed kernel-doc instead - even though this is teaching it to understand
> > > code that might go away (The comment for blk_end_request_callback says
> > > that it should not be used and will removed at some point). 
> > > 
> > > Any ideas on which is the best way to fix this?
> > 
> > Hi Richard,
> > Thanks for the patch.  I was planning to look into this problem
> > this weekend.
> > 
> > I think that changing scripts/kernel-doc to accept the current
> > kernel source tree usage is the right thing to do, even if the
> > block/blk code is a bit different.  I'll test it a bit and then
> > push it.
> 
> I'm not quite happy with the way that these function pointer
> parameters are presented.  E.g.,
> the callback function above is presented by kernel-doc as:
> 
> 		int ()(struct request *) drv_callback);
> whereas this
> 		int (drv_callback)(struct request *)
> would be much better.  If you could look into massaging that
> parameter output, that would be great.  If not, I'll look into
> later.

This simplest thing to do would be

-           push_parameter($param, $type, $file);
+           push_parameter($param, $arg, $file);

but then the function definition in the doc comes out as :- 

..., int (drv_callback)(struct request *)  drv_callback);

which is probably worse.

I don't see a simple way to fix this right now. But I'll let you know if
I come up with anything :)




> > I appreciate the patch.
> > 
> > > diff --git a/scripts/kernel-doc b/scripts/kernel-doc
> > > index 26146cb..68b2e4e 100755
> > > --- a/scripts/kernel-doc
> > > +++ b/scripts/kernel-doc
> > > @@ -1512,13 +1512,13 @@ sub create_parameterlist($$$) {
> > >  	    # corresponding data structures "correctly". Catch it later in
> > >  	    # output_* subs.
> > >  	    push_parameter($arg, "", $file);
> > > -	} elsif ($arg =~ m/\(.*\*/) {
> > > +	} elsif ($arg =~ m/\(.+\)\s*\(/) {
> > >  	    # pointer-to-function
> > >  	    $arg =~ tr/#/,/;
> > > -	    $arg =~ m/[^\(]+\(\*\s*([^\)]+)\)/;
> > > +	    $arg =~ m/[^\(]+\(\*?\s*(\w*)\s*\)/;
> > >  	    $param = $1;
> > >  	    $type = $arg;
> > > -	    $type =~ s/([^\(]+\(\*)$param/$1/;
> > > +	    $type =~ s/([^\(]+\(\*?)$param/$1/;
> > >  	    push_parameter($param, $type, $file);
> > >  	} elsif ($arg) {
> > >  	    $arg =~ s/\s*:\s*/:/g;
> 
> 
> ---
Richard