linux-kernel - [PATCH v2 2/2] LoongArch: Remove the deprecated notifier hook mechanism

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Message-ID: <BE6A6E80196F688F+20250209050258.2090416-3-wangyuli@uniontech.com>
Date: Sun,  9 Feb 2025 13:02:58 +0800
From: WangYuli <wangyuli@...ontech.com>
To: chenhuacai@...nel.org,
	kernel@...0n.name,
	guanwentao@...ontech.com,
	jiaxun.yang@...goat.com,
	wangyuli@...ontech.com
Cc: loongarch@...ts.linux.dev,
	linux-kernel@...r.kernel.org,
	chenlinxuan@...ontech.com,
	Thomas Gleixner <tglx@...utronix.de>,
	Tianyang Zhang <zhangtianyang@...ngson.cn>,
	Liupu Wang <wangliupu@...ngson.cn>,
	Bibo Mao <maobibo@...ngson.cn>
Subject: [PATCH v2 2/2] LoongArch: Remove the deprecated notifier hook mechanism

The notifier hook mechanism in proc and cpuinfo is actually unnecessary
for LoongArch because it's not used anywhere.

It was originally added to the MIPS code in commit d6d3c9afaab4 ("MIPS:
MT: proc: Add support for printing VPE and TC ids"), and LoongArch
then inherited it.

But as the kernel code stands now, this notifier hook mechanism doesn't
really make sense for either LoongArch or MIPS.

In addition, the seq_file declaration needs to be moved to its proper
place, as only the show_ipi_list() function in smp.c requires it.

Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Tianyang Zhang <zhangtianyang@...ngson.cn>
Cc: Liupu Wang <wangliupu@...ngson.cn>
Cc: Bibo Mao <maobibo@...ngson.cn>
Co-developed-by: Wentao Guan <guanwentao@...ontech.com>
Signed-off-by: Wentao Guan <guanwentao@...ontech.com>
Signed-off-by: Yuli Wang <wangyuli@...ontech.com>
---
 arch/loongarch/include/asm/cpu-info.h | 21 ---------------------
 arch/loongarch/include/asm/smp.h      |  1 +
 arch/loongarch/kernel/proc.c          | 22 ----------------------
 3 files changed, 1 insertion(+), 43 deletions(-)

diff --git a/arch/loongarch/include/asm/cpu-info.h b/arch/loongarch/include/asm/cpu-info.h
index 35e0a230a484..7f5bc0ad9d50 100644
--- a/arch/loongarch/include/asm/cpu-info.h
+++ b/arch/loongarch/include/asm/cpu-info.h
@@ -76,27 +76,6 @@ extern const char *__cpu_full_name[];
 #define cpu_family_string()	__cpu_family[raw_smp_processor_id()]
 #define cpu_full_name_string()	__cpu_full_name[raw_smp_processor_id()]
 
-struct seq_file;
-struct notifier_block;
-
-extern int register_proc_cpuinfo_notifier(struct notifier_block *nb);
-extern int proc_cpuinfo_notifier_call_chain(unsigned long val, void *v);
-
-#define proc_cpuinfo_notifier(fn, pri)					\
-({									\
-	static struct notifier_block fn##_nb = {			\
-		.notifier_call = fn,					\
-		.priority = pri						\
-	};								\
-									\
-	register_proc_cpuinfo_notifier(&fn##_nb);			\
-})
-
-struct proc_cpuinfo_notifier_args {
-	struct seq_file *m;
-	unsigned long n;
-};
-
 static inline bool cpus_are_siblings(int cpua, int cpub)
 {
 	struct cpuinfo_loongarch *infoa = &cpu_data[cpua];
diff --git a/arch/loongarch/include/asm/smp.h b/arch/loongarch/include/asm/smp.h
index 3383c9d24e94..34ba80c312d0 100644
--- a/arch/loongarch/include/asm/smp.h
+++ b/arch/loongarch/include/asm/smp.h
@@ -91,6 +91,7 @@ extern void calculate_cpu_foreign_map(void);
 /*
  * Generate IPI list text
  */
+struct seq_file;
 extern void show_ipi_list(struct seq_file *p, int prec);
 
 static inline void arch_send_call_function_single_ipi(int cpu)
diff --git a/arch/loongarch/kernel/proc.c b/arch/loongarch/kernel/proc.c
index 56a230238c9c..cea30768ae92 100644
--- a/arch/loongarch/kernel/proc.c
+++ b/arch/loongarch/kernel/proc.c
@@ -13,28 +13,12 @@
 #include <asm/processor.h>
 #include <asm/time.h>
 
-/*
- * No lock; only written during early bootup by CPU 0.
- */
-static RAW_NOTIFIER_HEAD(proc_cpuinfo_chain);
-
-int __ref register_proc_cpuinfo_notifier(struct notifier_block *nb)
-{
-	return raw_notifier_chain_register(&proc_cpuinfo_chain, nb);
-}
-
-int proc_cpuinfo_notifier_call_chain(unsigned long val, void *v)
-{
-	return raw_notifier_call_chain(&proc_cpuinfo_chain, val, v);
-}
-
 static int show_cpuinfo(struct seq_file *m, void *v)
 {
 	unsigned long n = (unsigned long) v - 1;
 	unsigned int isa = cpu_data[n].isa_level;
 	unsigned int version = cpu_data[n].processor_id & 0xff;
 	unsigned int fp_version = cpu_data[n].fpu_vers;
-	struct proc_cpuinfo_notifier_args proc_cpuinfo_notifier_args;
 
 #ifdef CONFIG_SMP
 	if (!cpu_online(n))
@@ -97,12 +81,6 @@ static int show_cpuinfo(struct seq_file *m, void *v)
 		      cpu_data[n].watch_ireg_count, cpu_data[n].watch_dreg_count);
 	}
 
-	proc_cpuinfo_notifier_args.m = m;
-	proc_cpuinfo_notifier_args.n = n;
-
-	raw_notifier_call_chain(&proc_cpuinfo_chain, 0,
-				&proc_cpuinfo_notifier_args);
-
 	seq_printf(m, "\n\n");
 
 	return 0;
-- 
2.47.2