Mark M. Hoffman wrote: > Hi Jim: > Hi Mark, thanks for taking an interest. > * Jim Cromie <jim.cromie at gmail.com> [2006-07-11 12:33:33 -0600]: > >> from the 18-rc1-mm1 announcement: >> >> - We're getting a relatively large number of crash reports coming out of the >> core sysfs/kobject/driver/bus code, and they're all really hard to diagnose. >> >> I am suspecting that what's happening is that some registration functions >> are failing and the caller is ignoring that failure. The code proceeds and >> crashes much later, in obscure ways. >> >> All these functions return error codes, and we're not checking them. We >> should. So there's a patch which marks all these things as __must_check, >> which causes around 1,500 new warnings. >> >> These are all bugs and they all need to be fixed. >> >> >> >> Many of these 1500 are from lm-sensors modules; >> for example - a single function - device_create_file(), >> is called 1027 times, and 'every' one is a void context return. >> >> grep device_create_file drivers/hwmon/*.c >> >> So, what kinds of errors are possible here ? >> and what should we do if they occur ? >> does it ever happen that only 1 create fails ? >> do/would we care ? (not currently) >> >> These Qs are somewhat rhetorical, theyre at least a heads-up. >> > > I can't resist answering rhetorical questions. ;) > > At least in the context of what Andrew wrote, the calls to device_create_file() > in the hwmon drivers are not the problem. AFAICT, if one or more sysfs files > fail to be created, the worst that might happen is that *maybe* sensors(1) could > crash. Offhand, I can't see how missing sysfs files could lead to a kernel crash. > > At any rate, yes, they're still bugs. > > OTOH, there is a real need to review some of the error checking in the I2C > core - where ignoring status can and does cause kernel panics. See some > recent patches by both Jean and me for examples... and there are more. > > >> FWIW, device_remove_file() is only called 9 times. >> 8 from hwmon/ams.c 1 from hwmon/lm70.c This compares rather sparsely against: [jimc at harpo linux-2.6.18-rc2-mm1-sk]$ grep device_create_file drivers/hwmon/*.c |wc 1027 3046 83340 Is it truly this optional ? >> This doesnt seem to be a problem though, or we'd have heard it by now. >> Specifically - hwmon/pc87360 appears to clean up after itself, >> (or rather sysfs core code does), without any calls to device_remove_file() >> >> soekris:/sys/bus/i2c/devices# ls >> 9191-6620@ >> soekris:/sys/bus/i2c/devices# rmmod pc87360 >> soekris:/sys/bus/i2c/devices# ls >> soekris:/sys/bus/i2c/devices# >> >> >> Ive gone ahead and worked up a patch against pc87360 to >> count-errors-and-warn, which should suffice, at least for short term. >> > > (Hopefully) I'll take a look at this later today. > > dashed-hopes ;-) If you'd rather punt, I'll send it on to lkml, but I suppose Id like to keep it in-channel. > Regards, > > thanks -jimc
