On Wed, Feb 26, 2020 at 10:33 AM Alexey Gladkov
[off-list ref] wrote:

On Wed, Feb 26, 2020 at 04:53:45AM +0200, Denis Kaganovich wrote:

quoted

After commit e7e2cb61fa9f1db3429d91ef6accff549500d268, even if real filename
passed - modinfo show info from context (so, I got built-in info from
running
kernel, but asking for new kernel's external module). This behaviour
unobvious
and incompatible with pre-v27. Simple use fake context for filename - IMHO
much less ugly then current results.

Can you give an example of this misbehavior ?

I have a two kernel directories (generic and current) with
modules.builtin.modinfo:

$ ls -1 /lib/modules/{5.2.0-generic,`uname -r`}/modules.builtin.modinfo
/lib/modules/5.2.0-generic/modules.builtin.modinfo
/lib/modules/5.2.0-current/modules.builtin.modinfo

The ext4 module is built into both:

$ tr '\0' '\n' < /lib/modules/`uname -r`/modules.builtin.modinfo |grep ^ext4.description
ext4.description=Fourth Extended Filesystem

$ tr '\0' '\n' < /lib/modules/5.2.0-generic/modules.builtin.modinfo |grep ^ext4.description
ext4.description=Fourth Extended Filesystem

Now I have build this module separately and put it into the tree:

that's why you don't have this problem. If you just build a new
ext4.ko module and give it
in the command line without putting it into the tree, then this
problem would be triggered.

$ ~/p/kmod/tools/modinfo fs/ext4/ext4.ko
filename:       /home/ldmartin/p/gfx-internal/drm-intel-internal/fs/ext4/ext4.ko
modinfo: ERROR: could not get modinfo from 'ext4': No such file or directory

$ modinfo fs/ext4/ext4.ko
filename:       /home/ldmartin/p/gfx-internal/drm-intel-internal/fs/ext4/ext4.ko
softdep:        pre: crc32c
license:        GPL
description:    Fourth Extended Filesystem
author:         Remy Card, Stephen Tweedie, Andrew Morton, Andreas
Dilger, Theodore Ts'o and others
alias:          fs-ext4
alias:          ext3
alias:          fs-ext3
alias:          ext2
alias:          fs-ext2
depends:        mbcache,jbd2
retpoline:      Y
intree:         Y
name:           ext4
vermagic:       5.4.17+ SMP preempt mod_unload

Lucas De Marchi

$ find /lib/modules/{5.2.0-generic,`uname -r`} -name 'ext4.*'
/lib/modules/5.2.0-generic/kernel/fs/ext4/ext4.ko.gz

For current kernel:

$ tools/modinfo ext4 |grep filename
filename: (builtin)

For the other kernel:

$ tools/modinfo -k 5.2.0-generic ext4 |grep filename
filename: /lib/modules/5.2.0-generic/kernel/fs/ext4/ext4.ko.gz

Only the external module is displayed, even if there is a module with the
same name in the modules.builtin.modinfo.

I also have a very old kernel without modules.builtin.modinfo:

$ tools/modinfo -k 4.14.96-generic ext4 |grep filename
filename: /lib/modules/4.14.96-generic/kernel/fs/ext4/ext4.ko.gz

quoted

Signed-off-by: Dzianis Kahanovich <redacted>

--- a/tools/modinfo.c 2020-02-25 13:46:38.181693570 +0300
+++ b/tools/modinfo.c 2020-02-26 05:18:39.393790919 +0300

@@ -359,7 +359,7 @@ static bool is_module_filename(const cha

 static int do_modinfo(int argc, char *argv[])
 {
-     struct kmod_ctx *ctx;
+     struct kmod_ctx *ctx, *ctx0;
      char dirname_buf[PATH_MAX];
      const char *dirname = NULL;
      const char *kversion = NULL;

@@ -437,7 +437,8 @@ static int do_modinfo(int argc, char *ar
      }

      ctx = kmod_new(dirname, &null_config);
-     if (!ctx) {
+     ctx0 = kmod_new("/dev/null", &null_config);
+     if (!ctx || !ctx0) {
              ERR("kmod_new() failed!\n");
              return EXIT_FAILURE;
      }

@@ -448,7 +449,7 @@ static int do_modinfo(int argc, char *ar
              int r;

              if (is_module_filename(name))
-                     r = modinfo_path_do(ctx, name);
+                     r = modinfo_path_do(ctx0, name);
              else
                      r = modinfo_alias_do(ctx, name);

@@ -456,6 +457,7 @@ static int do_modinfo(int argc, char *ar
                      err = r;
      }

+     kmod_unref(ctx0);
      kmod_unref(ctx);
      return err >= 0 ? EXIT_SUCCESS : EXIT_FAILURE;
 }

--
Rgrds, legion

-- 
Lucas De Marchi