[PATCH 1/2] module: Fix ERRORs reported by checkpatch.pl

[PATCH 1/2] module: Fix ERRORs reported by checkpatch.pl

[Christophe Leroy]

Checkpatch reports following errors:

ERROR: do not use assignment in if condition
+	if ((colon = strnchr(name, MODULE_NAME_LEN, ':')) != NULL) {

ERROR: do not use assignment in if condition
+		if ((mod = find_module_all(name, colon - name, false)) != NULL)

ERROR: do not use assignment in if condition
+			if ((ret = find_kallsyms_symbol_value(mod, name)) != 0)

ERROR: do not initialise globals to 0
+int modules_disabled = 0;

ERROR: do not use assignment in if condition
+	if (wait_event_interruptible_timeout(module_wq,

Fix them.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
---
 kernel/module/kallsyms.c | 9 ++++++---
 kernel/module/main.c     | 6 +++---
 2 files changed, 9 insertions(+), 6 deletions(-)

diff --git a/kernel/module/kallsyms.c b/kernel/module/kallsyms.c
index 3e11523bc6f6..fe3636bde605 100644
--- a/kernel/module/kallsyms.c
+++ b/kernel/module/kallsyms.c
@@ -457,14 +457,17 @@ unsigned long module_kallsyms_lookup_name(const char *name)
 
 	/* Don't lock: we're in enough trouble already. */
 	preempt_disable();
-	if ((colon = strnchr(name, MODULE_NAME_LEN, ':')) != NULL) {
-		if ((mod = find_module_all(name, colon - name, false)) != NULL)
+	colon = strnchr(name, MODULE_NAME_LEN, ':');
+	if (colon) {
+		mod = find_module_all(name, colon - name, false);
+		if (mod)
 			ret = find_kallsyms_symbol_value(mod, colon + 1);
 	} else {
 		list_for_each_entry_rcu(mod, &modules, list) {
 			if (mod->state == MODULE_STATE_UNFORMED)
 				continue;
-			if ((ret = find_kallsyms_symbol_value(mod, name)) != 0)
+			ret = find_kallsyms_symbol_value(mod, name);
+			if (ret)
 				break;
 		}
 	}
diff --git a/kernel/module/main.c b/kernel/module/main.c
index 0548151dd933..36747941817f 100644
--- a/kernel/module/main.c
+++ b/kernel/module/main.c
@@ -119,7 +119,7 @@ static void mod_update_bounds(struct module *mod)
 }
 
 /* Block module loading/unloading? */
-int modules_disabled = 0;
+int modules_disabled;
 core_param(nomodule, modules_disabled, bint, 0);
 
 /* Waiting for a module to finish initializing? */
@@ -1111,9 +1111,9 @@ resolve_symbol_wait(struct module *mod,
 	const struct kernel_symbol *ksym;
 	char owner[MODULE_NAME_LEN];
 
+	ksym = resolve_symbol(mod, info, name, owner);
 	if (wait_event_interruptible_timeout(module_wq,
-			!IS_ERR(ksym = resolve_symbol(mod, info, name, owner))
-			|| PTR_ERR(ksym) != -EBUSY,
+			!IS_ERR(ksym) || PTR_ERR(ksym) != -EBUSY,
 					     30 * HZ) <= 0) {
 		pr_warn("%s: gave up waiting for init of module %s.\n",
 			mod->name, owner);
-- 
2.35.3

[PATCH 2/2] module: Increase readability of module_kallsyms_lookup_name()

[Christophe Leroy]

module_kallsyms_lookup_name() has several exit conditions but
can't return immediately due to preempt_disable().

Refactor module_kallsyms_lookup_name() to allow returning from
anywhere, and reduce depth.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
---
 kernel/module/kallsyms.c | 38 ++++++++++++++++++++++++--------------
 1 file changed, 24 insertions(+), 14 deletions(-)

diff --git a/kernel/module/kallsyms.c b/kernel/module/kallsyms.c
index fe3636bde605..df0150c467d4 100644
--- a/kernel/module/kallsyms.c
+++ b/kernel/module/kallsyms.c
@@ -448,29 +448,39 @@ unsigned long find_kallsyms_symbol_value(struct module *mod, const char *name)
 	return 0;
 }
 
-/* Look for this name: can be of form module:name. */
-unsigned long module_kallsyms_lookup_name(const char *name)
+static unsigned long __module_kallsyms_lookup_name(const char *name)
 {
 	struct module *mod;
 	char *colon;
-	unsigned long ret = 0;
 
-	/* Don't lock: we're in enough trouble already. */
-	preempt_disable();
 	colon = strnchr(name, MODULE_NAME_LEN, ':');
 	if (colon) {
 		mod = find_module_all(name, colon - name, false);
 		if (mod)
-			ret = find_kallsyms_symbol_value(mod, colon + 1);
-	} else {
-		list_for_each_entry_rcu(mod, &modules, list) {
-			if (mod->state == MODULE_STATE_UNFORMED)
-				continue;
-			ret = find_kallsyms_symbol_value(mod, name);
-			if (ret)
-				break;
-		}
+			return find_kallsyms_symbol_value(mod, colon + 1);
+		return 0;
 	}
+
+	list_for_each_entry_rcu(mod, &modules, list) {
+		unsigned long ret;
+
+		if (mod->state == MODULE_STATE_UNFORMED)
+			continue;
+		ret = find_kallsyms_symbol_value(mod, name);
+		if (ret)
+			return ret;
+	}
+	return 0;
+}
+
+/* Look for this name: can be of form module:name. */
+unsigned long module_kallsyms_lookup_name(const char *name)
+{
+	unsigned long ret;
+
+	/* Don't lock: we're in enough trouble already. */
+	preempt_disable();
+	ret = __module_kallsyms_lookup_name(name);
 	preempt_enable();
 	return ret;
 }
-- 
2.35.3

Re: [PATCH 1/2] module: Fix ERRORs reported by checkpatch.pl

[Joe Perches]

On Sun, 2022-06-12 at 19:44 +0200, Christophe Leroy wrote:
> Checkpatch reports following errors:

There are many conditions that checkpatch reports that do
not need fixing.

checkpatch is a mindless script.  It's not always right.

> Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
[]
> diff --git a/kernel/module/main.c b/kernel/module/main.c
[]
> @@ -1111,9 +1111,9 @@ resolve_symbol_wait(struct module *mod,
>  	const struct kernel_symbol *ksym;
>  	char owner[MODULE_NAME_LEN];
>  
> +	ksym = resolve_symbol(mod, info, name, owner);
>  	if (wait_event_interruptible_timeout(module_wq,

Did you verify this change by looking at the code for
wait_event_interruptible_timeout?

> -			!IS_ERR(ksym = resolve_symbol(mod, info, name, owner))
> -			|| PTR_ERR(ksym) != -EBUSY,
> +			!IS_ERR(ksym) || PTR_ERR(ksym) != -EBUSY,
>  					     30 * HZ) <= 0) {
>  		pr_warn("%s: gave up waiting for init of module %s.\n",
>  			mod->name, owner);