Series comparison

From: Geliang Tang <tanggeliang@kylinos.cn>

This patch extracts duplicate code on error path when btf_get_module_btf()
returns NULL from the functions __register_btf_kfunc_id_set() and
register_btf_id_dtor_kfuncs() into a new helper named
register_check_missing_btf() to check CONFIG_DEBUG_INFO_BTF,
CONFIG_DEBUG_INFO_BTF_MODULES and CONFIG_MODULE_ALLOW_BTF_MISMATCH in it.

Signed-off-by: Geliang Tang <tanggeliang@kylinos.cn>
---
 kernel/bpf/btf.c | 43 +++++++++++++++++++++++--------------------
 1 file changed, 23 insertions(+), 20 deletions(-)

diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index XXXXXXX..XXXXXXX 100644
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -XXX,XX +XXX,XX @@
 #include <linux/bsearch.h>
 #include <linux/kobject.h>
 #include <linux/sysfs.h>
+#include <linux/module.h>
 
 #include <net/netfilter/nf_bpf_link.h>
 
@@ -XXX,XX +XXX,XX @@ static struct btf *btf_get_module_btf(const struct module *module)
 	return btf;
 }
 
+static int register_check_missing_btf(const struct module *module, const char *msg)
+{
+	if (!module && IS_ENABLED(CONFIG_DEBUG_INFO_BTF)) {
+		pr_err("missing vmlinux BTF, cannot register %s\n", msg);
+		return -ENOENT;
+	}
+	if (module && IS_ENABLED(CONFIG_DEBUG_INFO_BTF_MODULES)) {
+		if (IS_ENABLED(CONFIG_MODULE_ALLOW_BTF_MISMATCH)) {
+			pr_warn("allow module %s BTF mismatch, skip register %s\n",
+				module->name, msg);
+			return 0;
+		}
+		pr_err("missing module %s BTF, cannot register %s\n", module->name, msg);
+		return -ENOENT;
+	}
+	return 0;
+}
+
 BPF_CALL_4(bpf_btf_find_by_name_kind, char *, name, int, name_sz, u32, kind, int, flags)
 {
 	struct btf *btf = NULL;
@@ -XXX,XX +XXX,XX @@ static int __register_btf_kfunc_id_set(enum btf_kfunc_hook hook,
 	int ret, i;
 
 	btf = btf_get_module_btf(kset->owner);
-	if (!btf) {
-		if (!kset->owner && IS_ENABLED(CONFIG_DEBUG_INFO_BTF)) {
-			pr_err("missing vmlinux BTF, cannot register kfuncs\n");
-			return -ENOENT;
-		}
-		if (kset->owner && IS_ENABLED(CONFIG_DEBUG_INFO_BTF_MODULES))
-			pr_warn("missing module BTF, cannot register kfuncs\n");
-		return 0;
-	}
+	if (!btf)
+		return register_check_missing_btf(kset->owner, "kfuncs");
 	if (IS_ERR(btf))
 		return PTR_ERR(btf);
 
@@ -XXX,XX +XXX,XX @@ int register_btf_id_dtor_kfuncs(const struct btf_id_dtor_kfunc *dtors, u32 add_c
 	int ret;
 
 	btf = btf_get_module_btf(owner);
-	if (!btf) {
-		if (!owner && IS_ENABLED(CONFIG_DEBUG_INFO_BTF)) {
-			pr_err("missing vmlinux BTF, cannot register dtor kfuncs\n");
-			return -ENOENT;
-		}
-		if (owner && IS_ENABLED(CONFIG_DEBUG_INFO_BTF_MODULES)) {
-			pr_err("missing module BTF, cannot register dtor kfuncs\n");
-			return -ENOENT;
-		}
-		return 0;
-	}
+	if (!btf)
+		return register_check_missing_btf(owner, "dtor kfuncs");
 	if (IS_ERR(btf))
 		return PTR_ERR(btf);
 
-- 
2.40.1

From: Geliang Tang <tanggeliang@kylinos.cn>

To let the modules loaded, commit 3de4d22cc9ac ("bpf, btf: Warn but
return no error for NULL btf from __register_btf_kfunc_id_set()")
changes the return value of __register_btf_kfunc_id_set() from -ENOENT
to 0 when btf is NULL.

A better way to do this is to enable CONFIG_MODULE_ALLOW_BTF_MISMATCH.

An error code -ENOENT should indeed be returned when kernel module BTF
mismatch detected except CONFIG_MODULE_ALLOW_BTF_MISMATCH is enabled in
__register_btf_kfunc_id_set().

The same in register_btf_id_dtor_kfuncs(), give the modules a chance
to be loaded when CONFIG_MODULE_ALLOW_BTF_MISMATCH is enabled.

Fixes: 3de4d22cc9ac ("bpf, btf: Warn but return no error for NULL btf from __register_btf_kfunc_id_set()")
Signed-off-by: Geliang Tang <tanggeliang@kylinos.cn>
---
 kernel/bpf/btf.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index XXXXXXX..XXXXXXX 100644
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -XXX,XX +XXX,XX @@ static int __register_btf_kfunc_id_set(enum btf_kfunc_hook hook,
 			pr_err("missing vmlinux BTF, cannot register kfuncs\n");
 			return -ENOENT;
 		}
-		if (kset->owner && IS_ENABLED(CONFIG_DEBUG_INFO_BTF_MODULES))
+		if (kset->owner && IS_ENABLED(CONFIG_DEBUG_INFO_BTF_MODULES) &&
+		    !IS_ENABLED(CONFIG_MODULE_ALLOW_BTF_MISMATCH)) {
 			pr_warn("missing module BTF, cannot register kfuncs\n");
+			return -ENOENT;
+		}
 		return 0;
 	}
 	if (IS_ERR(btf))
@@ -XXX,XX +XXX,XX @@ int register_btf_id_dtor_kfuncs(const struct btf_id_dtor_kfunc *dtors, u32 add_c
 			pr_err("missing vmlinux BTF, cannot register dtor kfuncs\n");
 			return -ENOENT;
 		}
-		if (owner && IS_ENABLED(CONFIG_DEBUG_INFO_BTF_MODULES)) {
+		if (owner && IS_ENABLED(CONFIG_DEBUG_INFO_BTF_MODULES) &&
+		    !IS_ENABLED(CONFIG_MODULE_ALLOW_BTF_MISMATCH)) {
 			pr_err("missing module BTF, cannot register dtor kfuncs\n");
 			return -ENOENT;
 		}
-- 
2.40.1

From: Geliang Tang <tanggeliang@kylinos.cn>

This patch extracts duplicate code on error path when btf_get_module_btf()
returns NULL from the functions __register_btf_kfunc_id_set() and
register_btf_id_dtor_kfuncs() into a new helper named check_btf_kconfigs()
to check CONFIG_DEBUG_INFO_BTF, CONFIG_DEBUG_INFO_BTF_MODULES and
CONFIG_MODULE_ALLOW_BTF_MISMATCH in it.

Signed-off-by: Geliang Tang <tanggeliang@kylinos.cn>
---
 kernel/bpf/btf.c | 42 ++++++++++++++++++------------------------
 1 file changed, 18 insertions(+), 24 deletions(-)

diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index XXXXXXX..XXXXXXX 100644
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -XXX,XX +XXX,XX @@ static struct btf *btf_get_module_btf(const struct module *module)
 	return btf;
 }
 
+static int check_btf_kconfigs(const struct module *module)
+{
+	if (!module && IS_ENABLED(CONFIG_DEBUG_INFO_BTF)) {
+		pr_err("missing vmlinux BTF, cannot register kfuncs\n");
+		return -ENOENT;
+	}
+	if (module && IS_ENABLED(CONFIG_DEBUG_INFO_BTF_MODULES) &&
+	    !IS_ENABLED(CONFIG_MODULE_ALLOW_BTF_MISMATCH)) {
+		pr_err("missing module BTF, cannot register kfuncs\n");
+		return -ENOENT;
+	}
+	return 0;
+}
+
 BPF_CALL_4(bpf_btf_find_by_name_kind, char *, name, int, name_sz, u32, kind, int, flags)
 {
 	struct btf *btf = NULL;
@@ -XXX,XX +XXX,XX @@ static int __register_btf_kfunc_id_set(enum btf_kfunc_hook hook,
 	int ret, i;
 
 	btf = btf_get_module_btf(kset->owner);
-	if (!btf) {
-		if (!kset->owner && IS_ENABLED(CONFIG_DEBUG_INFO_BTF)) {
-			pr_err("missing vmlinux BTF, cannot register kfuncs\n");
-			return -ENOENT;
-		}
-		if (kset->owner && IS_ENABLED(CONFIG_DEBUG_INFO_BTF_MODULES) &&
-		    !IS_ENABLED(CONFIG_MODULE_ALLOW_BTF_MISMATCH)) {
-			pr_warn("missing module BTF, cannot register kfuncs\n");
-			return -ENOENT;
-		}
-		return 0;
-	}
+	if (!btf)
+		return check_btf_kconfigs(kset->owner);
 	if (IS_ERR(btf))
 		return PTR_ERR(btf);
 
@@ -XXX,XX +XXX,XX @@ int register_btf_id_dtor_kfuncs(const struct btf_id_dtor_kfunc *dtors, u32 add_c
 	int ret;
 
 	btf = btf_get_module_btf(owner);
-	if (!btf) {
-		if (!owner && IS_ENABLED(CONFIG_DEBUG_INFO_BTF)) {
-			pr_err("missing vmlinux BTF, cannot register dtor kfuncs\n");
-			return -ENOENT;
-		}
-		if (owner && IS_ENABLED(CONFIG_DEBUG_INFO_BTF_MODULES) &&
-		    !IS_ENABLED(CONFIG_MODULE_ALLOW_BTF_MISMATCH)) {
-			pr_err("missing module BTF, cannot register dtor kfuncs\n");
-			return -ENOENT;
-		}
-		return 0;
-	}
+	if (!btf)
+		return check_btf_kconfigs(owner);
 	if (IS_ERR(btf))
 		return PTR_ERR(btf);
 
-- 
2.40.1