bpf: btf: avoid -Wreturn-type warning

The stack_map_get_build_id_offset() function is too long for gcc to track whether 'work' may or may not be initialized at the end of it, leading to a false-positive warning:

kernel/bpf/stackmap.c: In function 'stack_map_get_build_id_offset':
kernel/bpf/stackmap.c:334:13: error: 'work' may be used uninitialized in this function [-Werror=maybe-uninitialized]

This removes the 'in_nmi_ctx' flag and uses the state of that variable itself to see if it got initialized.

Fixes bae77c5eb5b2 ("bpf: enable stackmap with build_id in nmi context")

Signed-off-by Arnd Bergmann <[email protected]>

---
kernel/bpf/stackmap.c | 7 +++----

1 file changed, 3 insertions(+), 4 deletions(-)

kernel/bpf/stackmap.c +3 -4

index b59ace0f0f09..b675a3f3d141 100644
@@ -285,11 +285,10 @@ static void stack_map_get_build_id_offset(struct bpf_stack_build_id *id_offs,
 {
 	int i;
 	struct vm_area_struct *vma;
-	bool in_nmi_ctx = in_nmi();
 	bool irq_work_busy = false;
-	struct stack_map_irq_work *work;
+	struct stack_map_irq_work *work = NULL;
 
-	if (in_nmi_ctx) {
+	if (in_nmi()) {
 		work = this_cpu_ptr(&up_read_work);
 		if (work->irq_work.flags & IRQ_WORK_BUSY)
 			/* cannot queue more up_read, fallback */

@@ -328,7 +327,7 @@ static void stack_map_get_build_id_offset(struct bpf_stack_build_id *id_offs,
 		id_offs[i].status = BPF_STACK_BUILD_ID_VALID;
 	}
 
-	if (!in_nmi_ctx) {
+	if (!work) {
 		up_read(&current->mm->mmap_sem);
 	} else {
 		work->sem = &current->mm->mmap_sem;

Signature · 1 line

2.9.0

The stack_map_get_build_id_offset() function is too long for gcc to track whether 'work' may or may not be initialized at the end of it, leading to a false-positive warning:

kernel/bpf/stackmap.c: In function 'stack_map_get_build_id_offset':
kernel/bpf/stackmap.c:334:13: error: 'work' may be used uninitialized in this function [-Werror=maybe-uninitialized]

This removes the 'in_nmi_ctx' flag and uses the state of that variable itself to see if it got initialized.

Fixes bae77c5eb5b2 ("bpf: enable stackmap with build_id in nmi context")

Signed-off-by Arnd Bergmann <[email protected]>

gcc warns about a noreturn function possibly returning in some configurations:

kernel/bpf/btf.c: In function 'env_type_is_resolve_sink':
kernel/bpf/btf.c:729:1: error: control reaches end of non-void function [-Werror=return-type]

Using BUG() instead of BUG_ON() avoids that warning and otherwise does the exact same thing.

Fixes eb3f595dab40 ("bpf: btf: Validate type reference")

Signed-off-by Arnd Bergmann <[email protected]>

---
kernel/bpf/btf.c | 2 +-

1 file changed, 1 insertion(+), 1 deletion(-)

kernel/bpf/btf.c +1 -1

index 9cbeabb5aca3..2822a0cf4f48 100644
@@ -749,7 +749,7 @@ static bool env_type_is_resolve_sink(const struct btf_verifier_env *env,
 			!btf_type_is_array(next_type) &&
 			!btf_type_is_struct(next_type);
 	default:
-		BUG_ON(1);
+		BUG();
 	}
 }
 

Signature · 1 line

2.9.0

gcc warns about a noreturn function possibly returning in some configurations:

kernel/bpf/btf.c: In function 'env_type_is_resolve_sink':
kernel/bpf/btf.c:729:1: error: control reaches end of non-void function [-Werror=return-type]

Using BUG() instead of BUG_ON() avoids that warning and otherwise does the exact same thing.

Fixes eb3f595dab40 ("bpf: btf: Validate type reference")

Signed-off-by Arnd Bergmann <[email protected]>