linux-kernel - [PATCH] module: Fix implicit type conversion

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Date:   Fri, 29 Oct 2021 02:06:09 +0000
From:   Jiasheng Jiang <jiasheng@...as.ac.cn>
To:     jeyu@...nel.org, ast@...nel.org, daniel@...earbox.net,
        andrii@...nel.org, kafai@...com, songliubraving@...com, yhs@...com,
        john.fastabend@...il.com, kpsingh@...nel.org, nathan@...nel.org,
        ndesaulniers@...gle.com
Cc:     linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
        bpf@...r.kernel.org, clang-built-linux@...glegroups.com,
        Jiasheng Jiang <jiasheng@...as.ac.cn>
Subject: [PATCH] module: Fix implicit type conversion

The variable 'cpu' is defined as unsigned int.
However in the for_each_possible_cpu, its values is assigned to -1.
That doesn't make sense and in the cpumask_next() it is implicitly
type conversed to int.
It is universally accepted that the implicit type conversion is
terrible.
Also, having the good programming custom will set an example for
others.
Thus, it might be better to change the definition of 'cpu' from
unsigned int to int.

Fixes: 10fad5e ("percpu, module: implement and use is_kernel/module_percpu_address()")
Signed-off-by: Jiasheng Jiang <jiasheng@...as.ac.cn>
---
 kernel/module.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/module.c b/kernel/module.c
index 927d46c..f10d611 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -632,7 +632,7 @@ static void percpu_modcopy(struct module *mod,
 bool __is_module_percpu_address(unsigned long addr, unsigned long *can_addr)
 {
 	struct module *mod;
-	unsigned int cpu;
+	int cpu;
 
 	preempt_disable();
 
-- 
2.7.4