| Message ID | 20180525213331.2115471-2-arnd@arndb.de |
|---|---|
| State | Accepted, archived |
| Delegated to: | BPF Maintainers |
| Headers | show |
| Series | [net-next,1/2] bpf: btf: avoid -Wreturn-type warning | expand |
> On May 25, 2018, at 2:33 PM, Arnd Bergmann <arnd@arndb.de> wrote: > > 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 <arnd@arndb.de> > --- > 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; > -- > 2.9.0 > Acked-by: Song Liu <songliubraving@fb.com>
On 05/25/2018 11:33 PM, Arnd Bergmann wrote: > 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 <arnd@arndb.de> Applied to bpf-next, thanks Arnd!
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;
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 <arnd@arndb.de> --- kernel/bpf/stackmap.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-)