Re: [PATCH v10 13/14] module: Move kdb module related code out of main kdb code

[Christophe Leroy]

Le 07/03/2022 à 18:47, Aaron Tomlin a écrit :
> No functional change.
> 
> This patch migrates the kdb 'lsmod' command support out of main
> kdb code into its own file under kernel/module. In addition to
> the above, a minor style warning i.e. missing a blank line after
> declarations, was resolved too. The new file was added to
> MAINTAINERS.
> 
> Signed-off-by: Aaron Tomlin <atomlin@xxxxxxxxxx>
> ---
>   MAINTAINERS                 |  1 +
>   include/linux/kdb.h         |  1 +
>   kernel/debug/kdb/kdb_main.c | 49 ---------------------------------
>   kernel/module/Makefile      |  1 +
>   kernel/module/kdb.c         | 55 +++++++++++++++++++++++++++++++++++++
>   kernel/module/main.c        |  4 ---
>   6 files changed, 58 insertions(+), 53 deletions(-)
>   create mode 100644 kernel/module/kdb.c
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 195cf1ac2ee8..40c717f93c1a 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -10689,6 +10689,7 @@ F:	drivers/tty/serial/kgdboc.c
>   F:	include/linux/kdb.h
>   F:	include/linux/kgdb.h
>   F:	kernel/debug/
> +F:	kernel/module/kdb.c
>   
>   KHADAS MCU MFD DRIVER
>   M:	Neil Armstrong <narmstrong@xxxxxxxxxxxx>
> diff --git a/include/linux/kdb.h b/include/linux/kdb.h
> index ea0f5e580fac..07dfb6a20a1c 100644
> --- a/include/linux/kdb.h
> +++ b/include/linux/kdb.h
> @@ -222,5 +222,6 @@ enum {
>   
>   extern int kdbgetintenv(const char *, int *);
>   extern int kdb_set(int, const char **);
> +int kdb_lsmod(int argc, const char **argv);
>   
>   #endif	/* !_KDB_H */
> diff --git a/kernel/debug/kdb/kdb_main.c b/kernel/debug/kdb/kdb_main.c
> index 0852a537dad4..f3a30cd5037f 100644
> --- a/kernel/debug/kdb/kdb_main.c
> +++ b/kernel/debug/kdb/kdb_main.c
> @@ -26,7 +26,6 @@
>   #include <linux/utsname.h>
>   #include <linux/vmalloc.h>
>   #include <linux/atomic.h>
> -#include <linux/module.h>
>   #include <linux/moduleparam.h>
>   #include <linux/mm.h>
>   #include <linux/init.h>

No need of linux/module.h here anymore ?

In that case, I see several other files in kernel/debug/kdb/ that 
include linux/module.h

Should it be removed in those files as well ?

> diff --git a/kernel/module/Makefile b/kernel/module/Makefile
> index cf8dcdc6b55f..88f5cdcdb067 100644
> --- a/kernel/module/Makefile
> +++ b/kernel/module/Makefile
> @@ -17,3 +17,4 @@ obj-$(CONFIG_DEBUG_KMEMLEAK) += debug_kmemleak.o
>   obj-$(CONFIG_KALLSYMS) += kallsyms.o
>   obj-$(CONFIG_PROC_FS) += procfs.o
>   obj-$(CONFIG_SYSFS) += sysfs.o
> +obj-$(CONFIG_KGDB_KDB) += kdb.o
> diff --git a/kernel/module/kdb.c b/kernel/module/kdb.c
> new file mode 100644
> index 000000000000..60baeebea3e0
> --- /dev/null
> +++ b/kernel/module/kdb.c
> @@ -0,0 +1,55 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + * Module kdb support
> + *
> + * Copyright (C) 2010 Jason Wessel
> + */
> +
> +#include <linux/module.h>
> +#include <linux/kdb.h>
> +#include "internal.h"
> +
> +/*
> + * kdb_lsmod - This function implements the 'lsmod' command.  Lists
> + *	currently loaded kernel modules.
> + *	Mostly taken from userland lsmod.
> + */
> +int kdb_lsmod(int argc, const char **argv)
> +{
> +	struct module *mod;
> +
> +	if (argc != 0)
> +		return KDB_ARGCOUNT;
> +
> +	kdb_printf("Module                  Size  modstruct     Used by\n");
> +	list_for_each_entry(mod, &modules, list) {
> +		if (mod->state == MODULE_STATE_UNFORMED)
> +			continue;
> +
> +		kdb_printf("%-20s%8u  0x%px ", mod->name,
> +			   mod->core_layout.size, (void *)mod);
> +#ifdef CONFIG_MODULE_UNLOAD
> +		kdb_printf("%4d ", module_refcount(mod));
> +#endif
> +		if (mod->state == MODULE_STATE_GOING)
> +			kdb_printf(" (Unloading)");
> +		else if (mod->state == MODULE_STATE_COMING)
> +			kdb_printf(" (Loading)");
> +		else
> +			kdb_printf(" (Live)");
> +		kdb_printf(" 0x%px", mod->core_layout.base);
> +
> +#ifdef CONFIG_MODULE_UNLOAD
> +		{
> +			struct module_use *use;
> +			kdb_printf(" [ ");
> +			list_for_each_entry(use, &mod->source_list,
> +					    source_list)
> +				kdb_printf("%s ", use->target->name);
> +			kdb_printf("]\n");
> +		}
> +#endif

That's a ugly construct. Could it be a function instead that you call 
from this loop,

Something like:

static void lsmod_in_use(struct module *mod)
{
#ifdef CONFIG_MODULE_UNLOAD
	struct module_use *use;
	kdb_printf(" [ ");
	list_for_each_entry(use, &mod->source_list,
			    source_list)
		kdb_printf("%s ", use->target->name);
	kdb_printf("]\n");
#endif
}


> +	}
> +
> +	return 0;
> +}
> diff --git a/kernel/module/main.c b/kernel/module/main.c
> index b8a59b5c3e3a..bcc4f7a82649 100644
> --- a/kernel/module/main.c
> +++ b/kernel/module/main.c
> @@ -108,10 +108,6 @@ static void mod_update_bounds(struct module *mod)
>   		__mod_update_bounds(mod->init_layout.base, mod->init_layout.size);
>   }
>   
> -#ifdef CONFIG_KGDB_KDB
> -struct list_head *kdb_modules = &modules; /* kdb needs the list of modules */

It should be removed from kernel/debug/kdb/kdb_private.h as well.

> -#endif /* CONFIG_KGDB_KDB */
> -
>   static void module_assert_mutex_or_preempt(void)
>   {
>   #ifdef CONFIG_LOCKDEP