diff mbox series

[3/3] modpost: move exit(1) for fatal() to modpost.h

Message ID 20231125103116.797608-3-masahiroy@kernel.org
State New
Headers
Series [1/3] modpost: move __attribute__((format(printf, 2, 3))) to modpost.h |

Commit Message

Masahiro Yamada Nov. 25, 2023, 10:31 a.m. UTC 
  fatal() never returns, but compilers are not aware of this fact because
exit(1) is called within the modpost_log() definition.

Move exit(1) to the fatal() macro so that compilers can identify
unreachable code flows.

Remove the initializer for 'taddr' in section_rel(), as compilers now
recognize this is not an uninitialized bug.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
---

 scripts/mod/modpost.c | 4 +---
 scripts/mod/modpost.h | 2 +-
 2 files changed, 2 insertions(+), 4 deletions(-)

Comments

Nathan Chancellor Nov. 30, 2023, 12:32 a.m. UTC | #1 
On Sat, Nov 25, 2023 at 07:31:16PM +0900, Masahiro Yamada wrote:
> fatal() never returns, but compilers are not aware of this fact because
> exit(1) is called within the modpost_log() definition.
> 
> Move exit(1) to the fatal() macro so that compilers can identify
> unreachable code flows.
> 
> Remove the initializer for 'taddr' in section_rel(), as compilers now
> recognize this is not an uninitialized bug.
> 
> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

While I did not see any warnings when testing, it seems like this patch
should come before patch 2 to avoid any potential problems from dropping
the unreachable code (since the compiler won't be able to infer that
fatal() is __noreturn without this change); doesn't really matter though
so:

Reviewed-by: Nathan Chancellor <nathan@kernel.org>

> ---
> 
>  scripts/mod/modpost.c | 4 +---
>  scripts/mod/modpost.h | 2 +-
>  2 files changed, 2 insertions(+), 4 deletions(-)
> 
> diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
> index 013fc5031bc7..696c583a14ec 100644
> --- a/scripts/mod/modpost.c
> +++ b/scripts/mod/modpost.c
> @@ -84,8 +84,6 @@ void modpost_log(enum loglevel loglevel, const char *fmt, ...)
>  	vfprintf(stderr, fmt, arglist);
>  	va_end(arglist);
>  
> -	if (loglevel == LOG_FATAL)
> -		exit(1);
>  	if (loglevel == LOG_ERROR)
>  		error_occurred = true;
>  }
> @@ -1415,7 +1413,7 @@ static void section_rel(struct module *mod, struct elf_info *elf,
>  
>  	for (rel = start; rel < stop; rel++) {
>  		Elf_Sym *tsym;
> -		Elf_Addr taddr = 0, r_offset;
> +		Elf_Addr taddr, r_offset;
>  		unsigned int r_type, r_sym;
>  		void *loc;
>  
> diff --git a/scripts/mod/modpost.h b/scripts/mod/modpost.h
> index 9fe974dc1a52..aaa67b24775e 100644
> --- a/scripts/mod/modpost.h
> +++ b/scripts/mod/modpost.h
> @@ -215,4 +215,4 @@ modpost_log(enum loglevel loglevel, const char *fmt, ...);
>   */
>  #define warn(fmt, args...)	modpost_log(LOG_WARN, fmt, ##args)
>  #define error(fmt, args...)	modpost_log(LOG_ERROR, fmt, ##args)
> -#define fatal(fmt, args...)	modpost_log(LOG_FATAL, fmt, ##args)
> +#define fatal(fmt, args...)	do { modpost_log(LOG_FATAL, fmt, ##args); exit(1); } while (1)
> -- 
> 2.40.1
>
Masahiro Yamada Dec. 3, 2023, 9:03 a.m. UTC | #2 
On Thu, Nov 30, 2023 at 9:32 AM Nathan Chancellor <nathan@kernel.org> wrote:
>
> On Sat, Nov 25, 2023 at 07:31:16PM +0900, Masahiro Yamada wrote:
> > fatal() never returns, but compilers are not aware of this fact because
> > exit(1) is called within the modpost_log() definition.
> >
> > Move exit(1) to the fatal() macro so that compilers can identify
> > unreachable code flows.
> >
> > Remove the initializer for 'taddr' in section_rel(), as compilers now
> > recognize this is not an uninitialized bug.
> >
> > Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
>
> While I did not see any warnings when testing, it seems like this patch
> should come before patch 2 to avoid any potential problems from dropping
> the unreachable code (since the compiler won't be able to infer that
> fatal() is __noreturn without this change); doesn't really matter though
> so:


My eyes spotted 2/3, but I can swap the patch order
and rephase the patch description because clang can
detect the unreachable code.













> Reviewed-by: Nathan Chancellor <nathan@kernel.org>
>
> > ---
> >
> >  scripts/mod/modpost.c | 4 +---
> >  scripts/mod/modpost.h | 2 +-
> >  2 files changed, 2 insertions(+), 4 deletions(-)
> >
> > diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
> > index 013fc5031bc7..696c583a14ec 100644
> > --- a/scripts/mod/modpost.c
> > +++ b/scripts/mod/modpost.c
> > @@ -84,8 +84,6 @@ void modpost_log(enum loglevel loglevel, const char *fmt, ...)
> >       vfprintf(stderr, fmt, arglist);
> >       va_end(arglist);
> >
> > -     if (loglevel == LOG_FATAL)
> > -             exit(1);
> >       if (loglevel == LOG_ERROR)
> >               error_occurred = true;
> >  }
> > @@ -1415,7 +1413,7 @@ static void section_rel(struct module *mod, struct elf_info *elf,
> >
> >       for (rel = start; rel < stop; rel++) {
> >               Elf_Sym *tsym;
> > -             Elf_Addr taddr = 0, r_offset;
> > +             Elf_Addr taddr, r_offset;
> >               unsigned int r_type, r_sym;
> >               void *loc;
> >
> > diff --git a/scripts/mod/modpost.h b/scripts/mod/modpost.h
> > index 9fe974dc1a52..aaa67b24775e 100644
> > --- a/scripts/mod/modpost.h
> > +++ b/scripts/mod/modpost.h
> > @@ -215,4 +215,4 @@ modpost_log(enum loglevel loglevel, const char *fmt, ...);
> >   */
> >  #define warn(fmt, args...)   modpost_log(LOG_WARN, fmt, ##args)
> >  #define error(fmt, args...)  modpost_log(LOG_ERROR, fmt, ##args)
> > -#define fatal(fmt, args...)  modpost_log(LOG_FATAL, fmt, ##args)
> > +#define fatal(fmt, args...)  do { modpost_log(LOG_FATAL, fmt, ##args); exit(1); } while (1)
> > --
> > 2.40.1
> >
>
diff mbox series

Patch

diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
index 013fc5031bc7..696c583a14ec 100644
--- a/scripts/mod/modpost.c
+++ b/scripts/mod/modpost.c
@@ -84,8 +84,6 @@  void modpost_log(enum loglevel loglevel, const char *fmt, ...)
 	vfprintf(stderr, fmt, arglist);
 	va_end(arglist);
 
-	if (loglevel == LOG_FATAL)
-		exit(1);
 	if (loglevel == LOG_ERROR)
 		error_occurred = true;
 }
@@ -1415,7 +1413,7 @@  static void section_rel(struct module *mod, struct elf_info *elf,
 
 	for (rel = start; rel < stop; rel++) {
 		Elf_Sym *tsym;
-		Elf_Addr taddr = 0, r_offset;
+		Elf_Addr taddr, r_offset;
 		unsigned int r_type, r_sym;
 		void *loc;
 
diff --git a/scripts/mod/modpost.h b/scripts/mod/modpost.h
index 9fe974dc1a52..aaa67b24775e 100644
--- a/scripts/mod/modpost.h
+++ b/scripts/mod/modpost.h
@@ -215,4 +215,4 @@  modpost_log(enum loglevel loglevel, const char *fmt, ...);
  */
 #define warn(fmt, args...)	modpost_log(LOG_WARN, fmt, ##args)
 #define error(fmt, args...)	modpost_log(LOG_ERROR, fmt, ##args)
-#define fatal(fmt, args...)	modpost_log(LOG_FATAL, fmt, ##args)
+#define fatal(fmt, args...)	do { modpost_log(LOG_FATAL, fmt, ##args); exit(1); } while (1)