[PATCH] init: Remove strlcat() and sprintf() from do_one_initcall()

[PATCH] init: Remove strlcat() and sprintf() from do_one_initcall()

[Thorsten Blum]

In preparation for removing strlcat() from the kernel [1], format the
warning directly in WARN(). This also removes the temporary 64-byte
buffer and the sprintf() call while preserving the warning text.

Link: https://github.com/KSPP/linux/issues/370 [1]
Signed-off-by: Thorsten Blum <blum@kernel.org>
---
 init/main.c | 21 +++++++++++----------
 1 file changed, 11 insertions(+), 10 deletions(-)

diff --git a/init/main.c b/init/main.c
index 93a2b12976f0..430b403e0880 100644
--- a/init/main.c
+++ b/init/main.c
@@ -1397,7 +1397,8 @@ static inline void do_trace_initcall_level(const char *level)
 int __init_or_module do_one_initcall(initcall_t fn)
 {
 	int count = preempt_count();
-	char msgbuf[64];
+	bool preempt_imbalanced;
+	bool irqs_left_disabled;
 	int ret;
 
 	if (initcall_blacklisted(fn))
@@ -1407,17 +1408,17 @@ int __init_or_module do_one_initcall(initcall_t fn)
 	ret = fn();
 	do_trace_initcall_finish(fn, ret);
 
-	msgbuf[0] = 0;
-
-	if (preempt_count() != count) {
-		sprintf(msgbuf, "preemption imbalance ");
+	preempt_imbalanced = preempt_count() != count;
+	if (preempt_imbalanced)
 		preempt_count_set(count);
-	}
-	if (irqs_disabled()) {
-		strlcat(msgbuf, "disabled interrupts ", sizeof(msgbuf));
+
+	irqs_left_disabled = irqs_disabled();
+	if (irqs_left_disabled)
 		local_irq_enable();
-	}
-	WARN(msgbuf[0], "initcall %pS returned with %s\n", fn, msgbuf);
+
+	WARN(preempt_imbalanced || irqs_left_disabled, "initcall %pS returned with %s%s\n", fn,
+	     preempt_imbalanced ? "preemption imbalance " : "",
+	     irqs_left_disabled ? "disabled interrupts " : "");
 
 	add_latent_entropy();
 	return ret;

Re: [PATCH] init: Remove strlcat() and sprintf() from do_one_initcall()

[David Laight]

On Sat, 14 Nov 2026 12:05:31 +0100
Thorsten Blum <blum@kernel.org> wrote:

> In preparation for removing strlcat() from the kernel [1], format the
> warning directly in WARN(). This also removes the temporary 64-byte
> buffer and the sprintf() call while preserving the warning text.
> 
> Link: https://github.com/KSPP/linux/issues/370 [1]
> Signed-off-by: Thorsten Blum <blum@kernel.org>

This one actually makes sense!
I might have used 'const char *' variables and removed the ' ' before
the '\n'. But:

Reviewed-by: David Laight <david.laight.linux@gmail.com>

> ---
>  init/main.c | 21 +++++++++++----------
>  1 file changed, 11 insertions(+), 10 deletions(-)
> 
> diff --git a/init/main.c b/init/main.c
> index 93a2b12976f0..430b403e0880 100644
> --- a/init/main.c
> +++ b/init/main.c
> @@ -1397,7 +1397,8 @@ static inline void do_trace_initcall_level(const char *level)
>  int __init_or_module do_one_initcall(initcall_t fn)
>  {
>  	int count = preempt_count();
> -	char msgbuf[64];
> +	bool preempt_imbalanced;
> +	bool irqs_left_disabled;
>  	int ret;
>  
>  	if (initcall_blacklisted(fn))
> @@ -1407,17 +1408,17 @@ int __init_or_module do_one_initcall(initcall_t fn)
>  	ret = fn();
>  	do_trace_initcall_finish(fn, ret);
>  
> -	msgbuf[0] = 0;
> -
> -	if (preempt_count() != count) {
> -		sprintf(msgbuf, "preemption imbalance ");
> +	preempt_imbalanced = preempt_count() != count;
> +	if (preempt_imbalanced)
>  		preempt_count_set(count);
> -	}
> -	if (irqs_disabled()) {
> -		strlcat(msgbuf, "disabled interrupts ", sizeof(msgbuf));
> +
> +	irqs_left_disabled = irqs_disabled();
> +	if (irqs_left_disabled)
>  		local_irq_enable();
> -	}
> -	WARN(msgbuf[0], "initcall %pS returned with %s\n", fn, msgbuf);
> +
> +	WARN(preempt_imbalanced || irqs_left_disabled, "initcall %pS returned with %s%s\n", fn,
> +	     preempt_imbalanced ? "preemption imbalance " : "",
> +	     irqs_left_disabled ? "disabled interrupts " : "");
>  
>  	add_latent_entropy();
>  	return ret;
>