[PATCH bpf-next] scripts/bpf: Emit an #error directive known types list needs updating

[PATCH bpf-next] scripts/bpf: Emit an #error directive known types list needs updating

[Jakub Sitnicki]

Make the compiler report a clear error when bpf_helpers_doc.py needs
updating rather than rely on the fact that Clang fails to compile
English:

../../../lib/bpf/bpf_helper_defs.h:2707:1: error: unknown type name 'Unrecognized'
Unrecognized type 'struct bpf_inet_lookup', please add it to known types!

Signed-off-by: Jakub Sitnicki <jakub@cloudflare.com>
---
 scripts/bpf_helpers_doc.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/scripts/bpf_helpers_doc.py b/scripts/bpf_helpers_doc.py
index 7df9ce598ff9..08300bc024da 100755
--- a/scripts/bpf_helpers_doc.py
+++ b/scripts/bpf_helpers_doc.py
@@ -489,7 +489,7 @@ class PrinterHelpers(Printer):
         if t in self.mapped_types:
             return self.mapped_types[t]
         print("")
-        print("Unrecognized type '%s', please add it to known types!" % t)
+        print("#error \"Unrecognized type '%s', please add it to known types!\"" % t)
         sys.exit(1)
 
     seen_helpers = set()
-- 
2.20.1

Re: [PATCH bpf-next] scripts/bpf: Emit an #error directive known types list needs updating

[Daniel Borkmann]

On Wed, Oct 16, 2019 at 10:58:11AM +0200, Jakub Sitnicki wrote:
> Make the compiler report a clear error when bpf_helpers_doc.py needs
> updating rather than rely on the fact that Clang fails to compile
> English:
> 
> ../../../lib/bpf/bpf_helper_defs.h:2707:1: error: unknown type name 'Unrecognized'
> Unrecognized type 'struct bpf_inet_lookup', please add it to known types!
> 
> Signed-off-by: Jakub Sitnicki <jakub@cloudflare.com>

Applied, thanks!

Re: [PATCH bpf-next] scripts/bpf: Emit an #error directive known types list needs updating

[Andrii Nakryiko]

On Wed, Oct 16, 2019 at 6:21 AM Jakub Sitnicki <jakub@cloudflare.com> wrote:
>
> Make the compiler report a clear error when bpf_helpers_doc.py needs
> updating rather than rely on the fact that Clang fails to compile
> English:
>
> ../../../lib/bpf/bpf_helper_defs.h:2707:1: error: unknown type name 'Unrecognized'
> Unrecognized type 'struct bpf_inet_lookup', please add it to known types!
>
> Signed-off-by: Jakub Sitnicki <jakub@cloudflare.com>
> ---
>  scripts/bpf_helpers_doc.py | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/scripts/bpf_helpers_doc.py b/scripts/bpf_helpers_doc.py
> index 7df9ce598ff9..08300bc024da 100755
> --- a/scripts/bpf_helpers_doc.py
> +++ b/scripts/bpf_helpers_doc.py
> @@ -489,7 +489,7 @@ class PrinterHelpers(Printer):
>          if t in self.mapped_types:
>              return self.mapped_types[t]
>          print("")
> -        print("Unrecognized type '%s', please add it to known types!" % t)
> +        print("#error \"Unrecognized type '%s', please add it to known types!\"" % t)

My bad, this was intended to be printed to stderr, not to stdout
output. Can you please do a follow up patch turning this into eprint
instead?

This shouldn't be reported by Clang, rather by tool. And we should
ensure in libbpf's Makefile that bpf_helper_defs.h is deleted on
error. I'll do it a bit later, unless you'll beat me to it.

>          sys.exit(1)
>
>      seen_helpers = set()
> --
> 2.20.1
>

Re: [PATCH bpf-next] scripts/bpf: Emit an #error directive known types list needs updating

[Jakub Sitnicki]

On Wed, Oct 16, 2019 at 10:29 PM CEST, Andrii Nakryiko wrote:
> On Wed, Oct 16, 2019 at 6:21 AM Jakub Sitnicki <jakub@cloudflare.com> wrote:
>>
>> Make the compiler report a clear error when bpf_helpers_doc.py needs
>> updating rather than rely on the fact that Clang fails to compile
>> English:
>>
>> ../../../lib/bpf/bpf_helper_defs.h:2707:1: error: unknown type name 'Unrecognized'
>> Unrecognized type 'struct bpf_inet_lookup', please add it to known types!
>>
>> Signed-off-by: Jakub Sitnicki <jakub@cloudflare.com>
>> ---
>>  scripts/bpf_helpers_doc.py | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/scripts/bpf_helpers_doc.py b/scripts/bpf_helpers_doc.py
>> index 7df9ce598ff9..08300bc024da 100755
>> --- a/scripts/bpf_helpers_doc.py
>> +++ b/scripts/bpf_helpers_doc.py
>> @@ -489,7 +489,7 @@ class PrinterHelpers(Printer):
>>          if t in self.mapped_types:
>>              return self.mapped_types[t]
>>          print("")
>> -        print("Unrecognized type '%s', please add it to known types!" % t)
>> +        print("#error \"Unrecognized type '%s', please add it to known types!\"" % t)
>
> My bad, this was intended to be printed to stderr, not to stdout
> output. Can you please do a follow up patch turning this into eprint
> instead?
>
> This shouldn't be reported by Clang, rather by tool. And we should
> ensure in libbpf's Makefile that bpf_helper_defs.h is deleted on
> error. I'll do it a bit later, unless you'll beat me to it.

This sounds sensible. I could have guessed it. Here's the fix:

https://lore.kernel.org/bpf/20191017094416.7688-1-jakub@cloudflare.com/T/#u

-Jakub