Hi, Joe
On 12/30/20 1:35 PM, , Joe Perches wrote:
On Wed, 2020-12-30 at 12:13 +0800, Peng Wang wrote:
Some max_length wants to hold as large room as possible to
ensure enough size to tackle with the biggest NR_CPUS. As
an example below:
kernel/cgroup/cpuset.c:
static struct cftype legacy_files[] = {
{
.name = "cpus",
.seq_show = cpuset_common_seq_show,
.write = cpuset_write_resmask,
.max_write_len = (100U + 6 * NR_CPUS),
.private = FILE_CPULIST,
},
...
}
[]
diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
[]
@@ -7022,12 +7022,15 @@ sub process {
# use of NR_CPUS is usually wrong
# ignore definitions of NR_CPUS and usage to define arrays as likely right
+# ignore designated initializers using NR_CPUS
+
if ($line =~ /\bNR_CPUS\b/ &&
$line !~ /^.\s*\s*#\s*if\b.*\bNR_CPUS\b/ &&
$line !~ /^.\s*\s*#\s*define\b.*\bNR_CPUS\b/ &&
$line !~ /^.\s*$Declare\s.*\[[^\]]*NR_CPUS[^\]]*\]/ &&
$line !~ /\[[^\]]*\.\.\.[^\]]*NR_CPUS[^\]]*\]/ &&
- $line !~ /\[[^\]]*NR_CPUS[^\]]*\.\.\.[^\]]*\]/)
+ $line !~ /\[[^\]]*NR_CPUS[^\]]*\.\.\.[^\]]*\]/ &&
+ $line !~ /\s*\..*=.*\bNR_CPUS\b.*,$/)
{
WARN("NR_CPUS",
"usage of NR_CPUS is often wrong - consider using
cpu_possible(), num_possible_cpus(), for_each_possible_cpu(), etc\n" . $herecurr);
I wonder if it's worth it as there just aren't many of these: (6 total)
It does not look that much, but checkpatch.pl makes warning on this
especially when "0 errors, 0 warnings" is needed.
$ git grep -P '\..*=.*\bNR_CPUS\b.*,\s*$'
drivers/firmware/efi/efi.c: .cpu_bitmap = {
[BITS_TO_LONGS(NR__CPUS)] = 0},
drivers/infiniband/hw/hfi1/sdma.c: .max_size = NR_CPUS,
init/init_task.c: .nr_cpus_allowed= NR_CPUS,
kernel/cgroup/cpuset.c: .max_write_len = (100U + 6 * NR_CPUS),
kernel/cgroup/cpuset.c: .max_write_len = (100U + 6 * NR_CPUS),
kernel/sysctl.c: .maxlen = NR_CPUS,
It also seems it might be more sensible as:
$line !~ /^.\s*\.\w+\s*=\s*.*\bNR_CPUS\b/
Aha, this is better!
Will send a v2 patch including this if you don't mind, Thanks.
Which finds a couple more:
$ git grep -P '^\s*\.\w+\s*=\s*.*\bNR_CPUS\b'
arch/arm64/include/asm/processor.h: .fpsimd_cpu = NR_CPUS,
\
arch/powerpc/kernel/prom_init.c: .max_cpus =
cpu_to_be32(NR_CPUS), /* number of cores supported */
drivers/firmware/efi/efi.c: .cpu_bitmap = {
[BITS_TO_LONGS(NR_CPUS)] = 0},
drivers/infiniband/hw/hfi1/sdma.c: .max_size = NR_CPUS,
init/init_task.c: .nr_cpus_allowed= NR_CPUS,
kernel/cgroup/cpuset.c: .max_write_len = (100U + 6 * NR_CPUS),
kernel/cgroup/cpuset.c: .max_write_len = (100U + 6 * NR_CPUS),
kernel/sysctl.c: .maxlen = NR_CPUS,
