Hi Andre, On Thu, 5 Feb 2009 10:03:31 +0100, Andre Prendel wrote: > Sysfs directory of the hwmon devices contains directories and symlinks. > > Here is the output on my Thinkpad: > > andre at ubuntu:/sys/class/hwmon/hwmon0/device$ ls -l > insgesamt 0 > lrwxrwxrwx 1 root root 0 2009-02-04 19:44 bus -> ../../../bus/platform > lrwxrwxrwx 1 root root 0 2009-02-04 19:42 driver -> > ../../../bus/platform/drivers/thinkpad_hwmon > -r--r--r-- 1 root root 4096 2009-02-04 19:44 fan1_input > lrwxrwxrwx 1 root root 0 2009-02-04 19:44 hwmon:hwmon0 -> > ../../../class/hwmon/hwmon0 > -r--r--r-- 1 root root 4096 2009-02-04 19:44 modalias > -r--r--r-- 1 root root 4096 2009-02-04 19:44 name > drwxr-xr-x 2 root root 0 2009-02-04 19:44 power > -rw-r--r-- 1 root root 4096 2009-02-04 19:44 pwm1 > -rw-r--r-- 1 root root 4096 2009-02-04 19:44 pwm1_enable > lrwxrwxrwx 1 root root 0 2009-02-04 19:42 subsystem -> > ../../../bus/platform > -r--r--r-- 1 root root 4096 2009-02-04 19:44 temp10_input > -r--r--r-- 1 root root 4096 2009-02-04 19:44 temp11_input > -r--r--r-- 1 root root 4096 2009-02-04 19:44 temp12_input > [...] > > IMO we can ignore them looking for subfeatures (in > sensors_read_dynamic_chip()), can't we? What problem are you trying to solve? > I assume there are no hidden files in the directory, right? That's the > reason why I have removed this from condition. I've never seen hidden files in sysfs except for sections in /sys/module. But the purpose of the original code was merely to skip "." and ".." anyway, not hidden files. > > Any comments or improvements? > > --- > --- lm-sensors-dev/lib/sysfs.c 2009-01-26 17:43:43.000000000 +0100 > +++ my-sensors-dev/lib/sysfs.c 2009-02-04 21:59:44.000000000 +0100 > @@ -360,7 +360,8 @@ static int sensors_read_dynamic_chip(sen > char *name = ent->d_name; > int nr; > > - if (ent->d_name[0] == '.') > + /* Skip directories and symlinks. */ > + if (ent->d_type == DT_DIR || ent->d_type == DT_LNK) > continue; > > sftype = sensors_subfeature_get_type(name, &nr); Links must always be handled with care, sometimes sysfs turns directories into links or vice-versa and it has broken user-space code in the past. But I guess we can safely assume that device attributes will never be links? If you really care about performance (and I guess that's the sole purpose of your patch) then it's faster to check for ent->d_type != DT_REG. You can also move "name = ent->d_name" after this test to make the fast path even faster. Out of curiosity, did you actually measure any performance improvement with your patch? -- Jean Delvare
