Messages in this thread | | | Date | Tue, 3 Apr 2012 12:16:23 +0200 | From | Ingo Molnar <> | Subject | Re: [PATCH] Prevent crash on missing sysfs attribute group |
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* Eric W. Biederman <ebiederm@xmission.com> wrote:
> Ingo Molnar <mingo@kernel.org> writes: > > > * Eric W. Biederman <ebiederm@xmission.com> wrote: > > > >> > Huh, so put repeated, duplicated, inconsistently applied sanity > >> > checks into dozens of sysfs attribute using kernel subsystems? > >> > >> [...] > >> > >> No. I was not talking about every usage site. > > > > Note, I'm not arguing that this isn't a bug in the P4 PMU driver > > - it is clearly a bug and I've applied the fix for it. I'm > > arguing about the escallation vector that this bug takes - that > > is unnecessarily disruptive: > > > > You were talking about: > > > >> >> FIX perf to include sanity checks. > > > > and what the PMU drivers do here is not uncommon at all, and the > > bug (for which I applied the fix and will push to Linus ASAP) is > > not uncommon either: > > > Bugs happen and indirections happen too. perf uses a generic > > PMU driver layer where the lower level layers register > > themselves. There's at least a dozen similar constructs in > > the kernel and you suggest that the right solution is to put > > checks in every one of them, while the nice patch from Bruno > > could catch it too, in one central place? > > What is uncommon is that perf_pmu_register is called from an > early initcall, and then later a device_init call is used to > register the pmu subsystem with sysfs.
This has no relevance to the bug and crash pattern itself whatsoever, so stop blathering about unrelated things.
Not filling out a sysfs object attribute is an *easy* driver level mistake, I've seen it happen on numerous occasions. Not crashing on it in the sysfs layer is an *obvious* debugging helper, and I don't understand why you are even arguing about this.
Thanks,
Ingo
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