On Mon, Jun 04, 2018 at 07:47:30PM +0200, Matthias Reichl wrote: > Hi Sean, > > I finally found the time to test your patch series and noticed > 2 issues - comments are inline > > On Sun, May 27, 2018 at 12:24:09PM +0100, Sean Young wrote: > > diff --git a/drivers/media/rc/Kconfig b/drivers/media/rc/Kconfig > > index eb2c3b6eca7f..d5b35a6ba899 100644 > > --- a/drivers/media/rc/Kconfig > > +++ b/drivers/media/rc/Kconfig > > @@ -25,6 +25,19 @@ config LIRC > > passes raw IR to and from userspace, which is needed for > > IR transmitting (aka "blasting") and for the lirc daemon. > > > > +config BPF_LIRC_MODE2 > > + bool "Support for eBPF programs attached to lirc devices" > > + depends on BPF_SYSCALL > > + depends on RC_CORE=y > > Requiring rc-core to be built into the kernel could become > problematic in the future for people using media_build. > > Currently the whole media tree (including rc-core) can be built > as modules so DVB and IR drivers can be replaced by newer versions. > But with rc-core in the kernel things could easily break if internal > data structures are changed. > > Maybe we should add a small layer with a stable API/ABI between > bpf-lirc and rc-core to decouple them? Or would it be possible > to build rc-core with bpf support as a module? Unfortunately bpf cannot be built as a module. > > + depends on LIRC > > + help > > + Allow attaching eBPF programs to a lirc device using the bpf(2) > > + syscall command BPF_PROG_ATTACH. This is supported for raw IR > > + receivers. > > + > > + These eBPF programs can be used to decode IR into scancodes, for > > + IR protocols not supported by the kernel decoders. > > + > > menuconfig RC_DECODERS > > bool "Remote controller decoders" > > depends on RC_CORE > > [...] > > diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c > > index 388d4feda348..3c104113d040 100644 > > --- a/kernel/bpf/syscall.c > > +++ b/kernel/bpf/syscall.c > > @@ -11,6 +11,7 @@ > > */ > > #include <linux/bpf.h> > > #include <linux/bpf_trace.h> > > +#include <linux/bpf_lirc.h> > > #include <linux/btf.h> > > #include <linux/syscalls.h> > > #include <linux/slab.h> > > @@ -1578,6 +1579,8 @@ static int bpf_prog_attach(const union bpf_attr *attr) > > case BPF_SK_SKB_STREAM_PARSER: > > case BPF_SK_SKB_STREAM_VERDICT: > > return sockmap_get_from_fd(attr, BPF_PROG_TYPE_SK_SKB, true); > > + case BPF_LIRC_MODE2: > > + return lirc_prog_attach(attr); > > default: > > return -EINVAL; > > } > > @@ -1648,6 +1651,8 @@ static int bpf_prog_detach(const union bpf_attr *attr) > > case BPF_SK_SKB_STREAM_PARSER: > > case BPF_SK_SKB_STREAM_VERDICT: > > return sockmap_get_from_fd(attr, BPF_PROG_TYPE_SK_SKB, false); > > + case BPF_LIRC_MODE2: > > + return lirc_prog_detach(attr); > > default: > > return -EINVAL; > > } > > @@ -1695,6 +1700,8 @@ static int bpf_prog_query(const union bpf_attr *attr, > > case BPF_CGROUP_SOCK_OPS: > > case BPF_CGROUP_DEVICE: > > break; > > + case BPF_LIRC_MODE2: > > + return lirc_prog_query(attr, uattr); > > When testing this patch series I was wondering why I always got > -EINVAL when trying to query the registered programs. > > Closer inspection revealed that bpf_prog_attach/detach/query and > calls to them in the bpf syscall are in "#ifdef CONFIG_CGROUP_BPF" > blocks - and as I built the kernel without CONFIG_CGROUP_BPF > BPF_PROG_ATTACH/DETACH/QUERY weren't handled in the syscall switch > and I got -EINVAL from the bpf syscall function. > > I haven't checked in detail yet, but it looks to me like > bpf_prog_attach/detach/query could always be built (or when > either cgroup bpf or lirc bpf are enabled) and the #ifdefs moved > inside the switch(). So lirc bpf could be used without cgroup bpf. > Or am I missing something? You are right, this features depends on CONFIG_CGROUP_BPF right now. This also affects the BPF_SK_MSG_VERDICT, BPF_SK_SKB_STREAM_VERDICT and BPF_SK_SKB_STREAM_PARSER type bpf attachments, and as far as I know these shouldn't depend on CONFIG_CGROUP_BPF either. Sean
