[PATCH v2] softirq: Remove redundant h->action from preempt_count mismatch error

[PATCH v2] softirq: Remove redundant h->action from preempt_count mismatch error

[Enlin Mu]

When a preempt_count mismatch is detected in handle_softirqs(), the
error message currently prints the softirq action handler (h->action).

However, as Thomas Gleixner pointed out, the action handler for a given
softirq vector is always a known, fixed function (e.g., run_timer_softirq
for TIMER_SOFTIRQ). Printing it provides zero diagnostic value. The real
issue typically lies in the functions invoked *within* that handler, not
the handler entry point itself.

Therefore, as suggested by Sebastian Andrzej Siewior, remove h->action
from the print statement entirely to clean up the error message.

Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Suggested-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Enlin Mu <enlin.mu@unisoc.com>
Signed-off-by: Enlin Mu <enlin.mu@linux.dev>
---
v1 -> v2:
  - Instead of changing %p to %pS, remove h->action from the print
    entirely as suggested by Sebastian and Thomas.
  - Update commit message accordingly.

v1: https://lore.kernel.org/all/20260105094133.3542-1-enlin.mu@linux.dev/
---
 kernel/softirq.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/softirq.c b/kernel/softirq.c
index 7980a4a232f9..800d81c57302 100644
--- a/kernel/softirq.c
+++ b/kernel/softirq.c
@@ -645,8 +645,8 @@ static void handle_softirqs(bool ksirqd)
 		h->action();
 		trace_softirq_exit(vec_nr);
 		if (unlikely(prev_count != preempt_count())) {
-			pr_err("huh, entered softirq %u %s %p with preempt_count %08x, exited with %08x?\n",
-			       vec_nr, softirq_to_name[vec_nr], h->action,
+			pr_err("huh, entered softirq %u %s with preempt_count %08x, exited with %08x?\n",
+			       vec_nr, softirq_to_name[vec_nr],
 			       prev_count, preempt_count());
 			preempt_count_set(prev_count);
 		}
-- 
2.39.5

Re: [PATCH v2] softirq: Remove redundant h->action from preempt_count mismatch error

[Sebastian Andrzej Siewior]

On 2026-08-25 09:15:09 [+0800], Enlin Mu wrote:
> When a preempt_count mismatch is detected in handle_softirqs(), the
> error message currently prints the softirq action handler (h->action).
> 
> However, as Thomas Gleixner pointed out, the action handler for a given
> softirq vector is always a known, fixed function (e.g., run_timer_softirq
> for TIMER_SOFTIRQ). Printing it provides zero diagnostic value. The real
> issue typically lies in the functions invoked *within* that handler, not
> the handler entry point itself.
> 
> Therefore, as suggested by Sebastian Andrzej Siewior, remove h->action
> from the print statement entirely to clean up the error message.
> 
> Suggested-by: Thomas Gleixner <tglx@linutronix.de>
> Suggested-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
> Signed-off-by: Enlin Mu <enlin.mu@unisoc.com>
> Signed-off-by: Enlin Mu <enlin.mu@linux.dev>

Reviewed-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>

Sebastian

Re: [PATCH v2] softirq: Remove redundant h->action from preempt_count mismatch error

[Bradley Morgan]

On 25 August 2026 02:15:09 BST, Enlin Mu <enlin.mu@linux.dev> wrote:
>When a preempt_count mismatch is detected in handle_softirqs(), the
>error message currently prints the softirq action handler (h->action).
>
>However, as Thomas Gleixner pointed out, the action handler for a given
>softirq vector is always a known, fixed function (e.g., run_timer_softirq
>for TIMER_SOFTIRQ). Printing it provides zero diagnostic value. The real
>issue typically lies in the functions invoked *within* that handler, not
>the handler entry point itself.
>
>Therefore, as suggested by Sebastian Andrzej Siewior, remove h->action
>from the print statement entirely to clean up the error message.
>
>Suggested-by: Thomas Gleixner <tglx@linutronix.de>
>Suggested-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>

LGTM, thanks,

Reviewed-by: Bradley Morgan <include@grrlz.net>

>Signed-off-by: Enlin Mu <enlin.mu@unisoc.com>
>Signed-off-by: Enlin Mu <enlin.mu@linux.dev>
>---
>v1 -> v2:
>  - Instead of changing %p to %pS, remove h->action from the print
>    entirely as suggested by Sebastian and Thomas.
>  - Update commit message accordingly.
>
>v1: https://lore.kernel.org/all/20260105094133.3542-1-enlin.mu@linux.dev/
>---
> kernel/softirq.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
>diff --git a/kernel/softirq.c b/kernel/softirq.c
>index 7980a4a232f9..800d81c57302 100644
>--- a/kernel/softirq.c
>+++ b/kernel/softirq.c
>@@ -645,8 +645,8 @@ static void handle_softirqs(bool ksirqd)
> 		h->action();
> 		trace_softirq_exit(vec_nr);
> 		if (unlikely(prev_count != preempt_count())) {
>-			pr_err("huh, entered softirq %u %s %p with preempt_count %08x, exited with %08x?\n",
>-			       vec_nr, softirq_to_name[vec_nr], h->action,
>+			pr_err("huh, entered softirq %u %s with preempt_count %08x, exited with %08x?\n",
>+			       vec_nr, softirq_to_name[vec_nr],
> 			       prev_count, preempt_count());
> 			preempt_count_set(prev_count);
> 		}
>

Thanks!