From dc3b8ae9d271897e09b27fa4e4e0000de98590d1 Mon Sep 17 00:00:00 2001 From: Arnd Bergmann Date: Fri, 25 May 2018 23:33:20 +0200 Subject: bpf: avoid -Wmaybe-uninitialized 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 Acked-by: Song Liu Signed-off-by: Daniel Borkmann --- kernel/bpf/stackmap.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) diff --git a/kernel/bpf/stackmap.c b/kernel/bpf/stackmap.c index b59ace0f0f09..b675a3f3d141 100644 --- a/kernel/bpf/stackmap.c +++ b/kernel/bpf/stackmap.c @@ -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(¤t->mm->mmap_sem); } else { work->sem = ¤t->mm->mmap_sem; -- cgit v1.2.3-59-g8ed1b