PATCH] tracing: Fix unused tracepoints when module uses only exported ones

PATCH] tracing: Fix unused tracepoints when module uses only exported ones

[Steven Rostedt]

From: Steven Rostedt <rostedt@goodmis.org>

Building the KVM intel module failed to build with UT=1:

no __tracepoint_strings in file: arch/x86/kvm/kvm-intel.o
make[3]: *** [/work/git/test-linux.git/scripts/Makefile.modfinal:62: arch/x86/kvm/kvm-intel.ko] Error 1

The reason is that the module only uses the tracepoints defined and
exported by the main kvm module. The tracepoint-udpate.c code fails the
build if a tracepoint is used, but there's no tracepoints defined. But
this is acceptable in modules if the tracepoints is defined in the vmlinux
proper or another module and exported.

Do not fail to build if a tracepoint is used but no tracepoints are
defined if the code is a module. This should still never happen for the
vmlinux itself.

Fixes: e30f8e61e2518 ("tracing: Add a tracepoint verification check at build time")
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
---
 scripts/tracepoint-update.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/scripts/tracepoint-update.c b/scripts/tracepoint-update.c
index 7f7d90df14ce..90046aedc97b 100644
--- a/scripts/tracepoint-update.c
+++ b/scripts/tracepoint-update.c
@@ -210,6 +210,9 @@ static int process_tracepoints(bool mod, void *addr, const char *fname)
 	}
 
 	if (!tracepoint_data_sec) {
+		/* A module may reference only exported tracepoints */
+		if (mod)
+			return 0;
 		fprintf(stderr,	"no __tracepoint_strings in file: %s\n", fname);
 		return -1;
 	}
-- 
2.51.0

Re: PATCH] tracing: Fix unused tracepoints when module uses only exported ones

[Mathieu Desnoyers]

On 2025-12-08 08:53, Steven Rostedt wrote:
> From: Steven Rostedt <rostedt@goodmis.org>

Missing bracket for [PATCH] in subject.

> 
> Building the KVM intel module failed to build with UT=1:

failed -> fails (present ?)

> 
> no __tracepoint_strings in file: arch/x86/kvm/kvm-intel.o
> make[3]: *** [/work/git/test-linux.git/scripts/Makefile.modfinal:62: arch/x86/kvm/kvm-intel.ko] Error 1
> 
> The reason is that the module only uses the tracepoints defined and
> exported by the main kvm module. The tracepoint-udpate.c code fails the

I guess you mean "tracepoint-update.c" ?

> build if a tracepoint is used, but there's no tracepoints defined. But

tracepoint

> this is acceptable in modules if the tracepoints is defined in the vmlinux

tracepoint

> proper or another module and exported.
> 
> Do not fail to build if a tracepoint is used but no tracepoints are

tracepoint .. is

Thanks,

Mathieu

> defined if the code is a module. This should still never happen for the
> vmlinux itself.
> 
> Fixes: e30f8e61e2518 ("tracing: Add a tracepoint verification check at build time")
> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
> ---
>   scripts/tracepoint-update.c | 3 +++
>   1 file changed, 3 insertions(+)
> 
> diff --git a/scripts/tracepoint-update.c b/scripts/tracepoint-update.c
> index 7f7d90df14ce..90046aedc97b 100644
> --- a/scripts/tracepoint-update.c
> +++ b/scripts/tracepoint-update.c
> @@ -210,6 +210,9 @@ static int process_tracepoints(bool mod, void *addr, const char *fname)
>   	}
>   
>   	if (!tracepoint_data_sec) {
> +		/* A module may reference only exported tracepoints */
> +		if (mod)
> +			return 0;
>   		fprintf(stderr,	"no __tracepoint_strings in file: %s\n", fname);
>   		return -1;
>   	}


-- 
Mathieu Desnoyers
EfficiOS Inc.
https://www.efficios.com

Re: PATCH] tracing: Fix unused tracepoints when module uses only exported ones

[Steven Rostedt]

On Mon, 8 Dec 2025 09:22:48 -0500
Mathieu Desnoyers <mathieu.desnoyers@efficios.com> wrote:

> On 2025-12-08 08:53, Steven Rostedt wrote:
> > From: Steven Rostedt <rostedt@goodmis.org>  
> 
> Missing bracket for [PATCH] in subject.
> 
> > 
> > Building the KVM intel module failed to build with UT=1:  
> 
> failed -> fails (present ?)

After the patch is applied it will be in the past ;-)
> 
> > 
> > no __tracepoint_strings in file: arch/x86/kvm/kvm-intel.o
> > make[3]: *** [/work/git/test-linux.git/scripts/Makefile.modfinal:62: arch/x86/kvm/kvm-intel.ko] Error 1
> > 
> > The reason is that the module only uses the tracepoints defined and
> > exported by the main kvm module. The tracepoint-udpate.c code fails the  
> 
> I guess you mean "tracepoint-update.c" ?

Oops

> 
> > build if a tracepoint is used, but there's no tracepoints defined. But  
> 
> tracepoint

Actually, plural is fine here. Because it means one or more here.


> 
> > this is acceptable in modules if the tracepoints is defined in the vmlinux  
> 
> tracepoint

Actually, it should stay plural (as it is more than one), but needs s/is/are/

> 
> > proper or another module and exported.
> > 
> > Do not fail to build if a tracepoint is used but no tracepoints are  
> 
> tracepoint .. is
> 

Again, plural is OK here, but the other fixes can be done.

Although I see this right after I send a pull request to Linus, but
because I'm currently at the Maintainers Summit with Linus, and I don't
need to test this to fix it, I'll set up another pull request and tell
him to take the second one.

Thanks,

-- Steve


But, because it's just a change log fix and