On Tue, Jul 6, 2021 at 3:05 PM Andrii Nakryiko <andrii.nakryiko@xxxxxxxxx> wrote: > > On Tue, Jul 6, 2021 at 11:26 AM Yonghong Song <yhs@xxxxxx> wrote: > > > > > > > > On 7/6/21 10:44 AM, SanjayKumar J wrote: > > > task->state is renamed to task->__state in task_struct > > > > Could you add a reference to > > 2f064a59a11f ("sched: Change task_struct::state") > > which added this change? > > > > I think this should go to bpf tree as the change is in linus tree now. > > Could you annotate the tag as "[PATCH bpf]" ("[PATCH bpf v2]")? > > > > Please align comments to the left without margins. > > > > > > > > Signed-off-by: SanjayKumar J <vjsanjay@xxxxxxxxx> > > > > This Singed-off-by is not needed. > > > > You can add my Ack in the next revision: > > Acked-by: Yonghong Song <yhs@xxxxxx> > > > > > > > > Signed-off-by: SanjayKumar J <vjsanjay@xxxxxxxxx> > > > --- > > > tools/bpf/runqslower/runqslower.bpf.c | 2 +- > > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > > > diff --git a/tools/bpf/runqslower/runqslower.bpf.c b/tools/bpf/runqslower/runqslower.bpf.c > > > index 645530ca7e98..ab9353f2fd46 100644 > > > --- a/tools/bpf/runqslower/runqslower.bpf.c > > > +++ b/tools/bpf/runqslower/runqslower.bpf.c > > > @@ -74,7 +74,7 @@ int handle__sched_switch(u64 *ctx) > > > u32 pid; > > > > > > /* ivcsw: treat like an enqueue event and store timestamp */ > > > - if (prev->state == TASK_RUNNING) > > > + if (prev->__state == TASK_RUNNING) > > > > Currently, runqslower.bpf.c uses vmlinux.h. > > I am thinking to use bpf_core_field_exists(), but we need to > > single out task_struct structure from vmlinux.h > > with both state and __state fields, we could make it work > > by *changes* like > > > > #define task_struct task_struct_orig > > #include "vmlinux.h" > > #undef task_struct > > > > struct task_struct { > > ... state; > > ... __state; > > ... > > }; > > > no need for such surgery, recommended way is to use ___suffix to > declare incompatible struct definition: > > struct task_struct___old { > int state; > }; > > Then do casting in BPF code. We don't have to do it in kernel tree's > runqslower, but we'll definitely have to do that for libbpf-tools' > runqslower and runqlat. Question on this topic: state and __state are of different sizes here. IIUC, bpf_core_types_are_compat() does allow size mismatch. But it may cause problems in some cases, no? For example, would some combination make task->state return 32 extra bits from another field and cause confusion? Thanks, Song