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From:   John Hubbard <jhubbard@nvidia.com>
To:     Masahiro Yamada <masahiroy@kernel.org>
CC:     Nick Desaulniers <ndesaulniers@google.com>,
        Nathan Chancellor <nathan@kernel.org>,
        Tom Rix <trix@redhat.com>, Jason Gunthorpe <jgg@nvidia.com>,
        LKML <linux-kernel@vger.kernel.org>,
        clang-built-linux <llvm@lists.linux.dev>,
        John Hubbard <jhubbard@nvidia.com>
Subject: [PATCH v3] gen_compile_commands: handle multiple lines per .mod file
Date:   Mon, 27 Jun 2022 18:23:53 -0700
Message-ID: <20220628012353.13995-1-jhubbard@nvidia.com>
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scripts/clang-tools/gen_compile_commands.py incorrectly assumes that
each .mod file only contains one line. That assumption was correct when
the script was originally created, but commit 9413e7640564 ("kbuild:
split the second line of *.mod into *.usyms") changed the .mod file
format so that there is one entry per line, and potentially many lines.

The problem can be reproduced by using Kbuild to generate
compile_commands.json, like this:

    make CC=clang compile_commands.json

In many cases, the problem might be overlooked because many subsystems
only have one line anyway. However, in some subsystems (Nouveau, with
762 entries, is a notable example) it results in skipping most of the
subsystem.

Fix this by fully processing each .mod file.

Fixes: 9413e7640564 ("kbuild: split the second line of *.mod into *.usyms")
Cc: Masahiro Yamada <masahiroy@kernel.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: John Hubbard <jhubbard@nvidia.com>
---

Link to v2:
https://lore.kernel.org/all/20220616021149.327587-1-jhubbard@nvidia.com/

Changes since v2:

  * Restored a blank line.

  * Rewrote the commit description.

thanks,
John Hubbard


 scripts/clang-tools/gen_compile_commands.py | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/scripts/clang-tools/gen_compile_commands.py b/scripts/clang-tools/gen_compile_commands.py
index 1d1bde1fd45e..47da25b3ba7d 100755
--- a/scripts/clang-tools/gen_compile_commands.py
+++ b/scripts/clang-tools/gen_compile_commands.py
@@ -157,10 +157,10 @@ def cmdfiles_for_modorder(modorder):
             if ext != '.ko':
                 sys.exit('{}: module path must end with .ko'.format(ko))
             mod = base + '.mod'
-	    # The first line of *.mod lists the objects that compose the module.
+            # Read from *.mod, to get a list of objects that compose the module.
             with open(mod) as m:
-                for obj in m.readline().split():
-                    yield to_cmdfile(obj)
+                for mod_line in m:
+                    yield to_cmdfile(mod_line.rstrip())
 
 
 def process_line(root_directory, command_prefix, file_path):
-- 
2.36.1