On Mon, Sep 20, 2021 at 11:04 PM Muhammad Falak R Wani <falakreyaz@xxxxxxxxx> wrote: > > Simplify libbpf_num_possible_cpus by using sysconf(_SC_NPROCESSORS_CONF) > instead of parsing a file. > This patch is a part of libbpf-1.0 milestone. > > Reference: https://github.com/libbpf/libbpf/issue/383 I've been asking people to use a reference style like this, so that we don't confuse this with proper Linux tags. It's also useful to use "Closes: " keyword to let Github auto-close the issue when this patch eventually is synced into Github. So in this case I'd phrase everything as: "This patch is a part ([0]) of libbpf-1.0 milestone. [0] Closes: https://github.com/libbpf/libbpf/issue/383 Please update in the next revision. Also, keep in mind that we ask to use "[PATCH bpf-next]" prefix when submitting patches against the bpf-next kernel tree. It makes the intent clear and our BPF CI system knows which tree to test against. Thanks. > > Signed-off-by: Muhammad Falak R Wani <falakreyaz@xxxxxxxxx> > --- > tools/lib/bpf/libbpf.c | 16 +++------------- > 1 file changed, 3 insertions(+), 13 deletions(-) > > diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c > index da65a1666a5e..1d730b08ee44 100644 > --- a/tools/lib/bpf/libbpf.c > +++ b/tools/lib/bpf/libbpf.c > @@ -10765,25 +10765,15 @@ int parse_cpu_mask_file(const char *fcpu, bool **mask, int *mask_sz) > > int libbpf_num_possible_cpus(void) > { > - static const char *fcpu = "/sys/devices/system/cpu/possible"; > static int cpus; > - int err, n, i, tmp_cpus; > - bool *mask; > + int tmp_cpus; > > tmp_cpus = READ_ONCE(cpus); > if (tmp_cpus > 0) > return tmp_cpus; > > - err = parse_cpu_mask_file(fcpu, &mask, &n); > - if (err) > - return libbpf_err(err); > - > - tmp_cpus = 0; > - for (i = 0; i < n; i++) { > - if (mask[i]) > - tmp_cpus++; > - } > - free(mask); > + tmp_cpus = sysconf(_SC_NPROCESSORS_CONF); > + /* sysconf sets errno; no need to use libbpf_err */ I'd say it's still a good idea for explicitness and to show that we didn't forget about it :) Plus, if it actually ever fails, we don't want to WRITE_ONCE() here, so please follow the same error handling logic as it was previously with parse_cpu_mask_file. > > WRITE_ONCE(cpus, tmp_cpus); > return tmp_cpus; > -- > 2.17.1 >
