[PATCH bpf v4 1/3] bpf: Factor out stack_map_build_id_set_ip() in stackmap.c

[Ihor Solodrai <ihor.solodrai@linux.dev>]

Factor out a small helper from stack_map_get_build_id_offset() in
preparation for adding a sleepable build ID resolution path.

No functional changes.

Acked-by: Mykyta Yatsenko <yatsenko@meta.com>
Signed-off-by: Ihor Solodrai <ihor.solodrai@linux.dev>
---
 kernel/bpf/stackmap.c | 21 ++++++++++++---------
 1 file changed, 12 insertions(+), 9 deletions(-)

diff --git a/kernel/bpf/stackmap.c b/kernel/bpf/stackmap.c
index da3d328f5c15..4ef0fd06cea5 100644
--- a/kernel/bpf/stackmap.c
+++ b/kernel/bpf/stackmap.c
@@ -152,6 +152,12 @@ static int fetch_build_id(struct vm_area_struct *vma, unsigned char *build_id, b
 			 : build_id_parse_nofault(vma, build_id, NULL);
 }
 
+static inline void stack_map_build_id_set_ip(struct bpf_stack_build_id *id)
+{
+	id->status = BPF_STACK_BUILD_ID_IP;
+	memset(id->build_id, 0, BUILD_ID_SIZE_MAX);
+}
+
 /*
  * Expects all id_offs[i].ip values to be set to correct initial IPs.
  * They will be subsequently:
@@ -165,23 +171,21 @@ static int fetch_build_id(struct vm_area_struct *vma, unsigned char *build_id, b
 static void stack_map_get_build_id_offset(struct bpf_stack_build_id *id_offs,
 					  u32 trace_nr, bool user, bool may_fault)
 {
-	int i;
 	struct mmap_unlock_irq_work *work = NULL;
 	bool irq_work_busy = bpf_mmap_unlock_get_irq_work(&work);
+	bool has_user_ctx = user && current && current->mm;
 	struct vm_area_struct *vma, *prev_vma = NULL;
 	const char *prev_build_id;
+	int i;
 
 	/* If the irq_work is in use, fall back to report ips. Same
 	 * fallback is used for kernel stack (!user) on a stackmap with
 	 * build_id.
 	 */
-	if (!user || !current || !current->mm || irq_work_busy ||
-	    !mmap_read_trylock(current->mm)) {
+	if (!has_user_ctx || irq_work_busy || !mmap_read_trylock(current->mm)) {
 		/* cannot access current->mm, fall back to ips */
-		for (i = 0; i < trace_nr; i++) {
-			id_offs[i].status = BPF_STACK_BUILD_ID_IP;
-			memset(id_offs[i].build_id, 0, BUILD_ID_SIZE_MAX);
-		}
+		for (i = 0; i < trace_nr; i++)
+			stack_map_build_id_set_ip(&id_offs[i]);
 		return;
 	}
 
@@ -196,8 +200,7 @@ static void stack_map_get_build_id_offset(struct bpf_stack_build_id *id_offs,
 		vma = find_vma(current->mm, ip);
 		if (!vma || fetch_build_id(vma, id_offs[i].build_id, may_fault)) {
 			/* per entry fall back to ips */
-			id_offs[i].status = BPF_STACK_BUILD_ID_IP;
-			memset(id_offs[i].build_id, 0, BUILD_ID_SIZE_MAX);
+			stack_map_build_id_set_ip(&id_offs[i]);
 			continue;
 		}
 build_id_valid:
-- 
2.54.0