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Groups > linux.kernel > #1504714
| From | Jiri Olsa <jolsa@redhat.com> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: [4.9-rc1+] intel_uncore builtin + CONFIG_DEBUG_TEST_DRIVER_REMOVE kernel panic |
| Date | 2016-10-20 11:50 +0200 |
| Message-ID | <sui93-5JM-7@gated-at.bofh.it> (permalink) |
| References | (4 earlier) <su0lQ-2yX-47@gated-at.bofh.it> <su4IO-5Ai-39@gated-at.bofh.it> <sueoN-3mL-1@gated-at.bofh.it> <suhmG-5dC-35@gated-at.bofh.it> <suhwm-5w9-23@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
On Thu, Oct 20, 2016 at 11:04:16AM +0200, Peter Zijlstra wrote:
> On Thu, Oct 20, 2016 at 10:58:03AM +0200, Jiri Olsa wrote:
>
> > @@ -8869,11 +8869,15 @@ void perf_pmu_unregister(struct pmu *pmu)
> > free_percpu(pmu->pmu_disable_count);
> > if (pmu->type >= PERF_TYPE_MAX)
> > idr_remove(&pmu_idr, pmu->type);
> > - if (pmu->nr_addr_filters)
> > - device_remove_file(pmu->dev, &dev_attr_nr_addr_filters);
> > - device_del(pmu->dev);
> > - put_device(pmu->dev);
> > + mutex_lock(&pmus_lock);
> > + if (pmu_bus_running) {
> > + if (pmu->nr_addr_filters)
> > + device_remove_file(pmu->dev, &dev_attr_nr_addr_filters);
> > + device_del(pmu->dev);
> > + put_device(pmu->dev);
> > + }
> > free_pmu_context(pmu);
> > + mutex_unlock(&pmus_lock);
> > }
> > EXPORT_SYMBOL_GPL(perf_pmu_unregister);
>
> I think that is still racy..
>
>
> unregister: sysfs_init:
>
> mutex_lock(&pmus_lock);
> list_del_rcu(&pmu->entry);
> mutex_unlock(&pmus_lock);
>
> synchronize_*rcu();
>
> mutex_lock(&pmus_lock);
> list_for_each_entry(pmu, &pmus, entry) {
> /* add device muck */
ah, I thought this part would add the device back.. but it's
already out of the pmu list.. right :-\
thanks,
jirka
> /* will _NOT_ see our PMU */
> }
> pmus_bus_running = 1;
> mutex_unlock(&pmus_lock);
>
> mutex_lock(&pmus_lock);
> if (pmu_bus_running) {
> device_del() /* OOPS */
>
>
> What you want is to read pmu_bus_running in the same pmus_lock section
> as we do the list_del, and then use that local copy later.
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[4.9-rc1+] intel_uncore builtin + CONFIG_DEBUG_TEST_DRIVER_REMOVE kernel panic CAI Qian <caiqian@redhat.com> - 2016-10-19 16:50 +0200
Re: [4.9-rc1+] intel_uncore builtin + CONFIG_DEBUG_TEST_DRIVER_REMOVE kernel panic Jiri Olsa <jolsa@redhat.com> - 2016-10-19 21:30 +0200
Re: [4.9-rc1+] intel_uncore builtin + CONFIG_DEBUG_TEST_DRIVER_REMOVE kernel panic CAI Qian <caiqian@redhat.com> - 2016-10-19 22:20 +0200
Re: [4.9-rc1+] intel_uncore builtin + CONFIG_DEBUG_TEST_DRIVER_REMOVE kernel panic Peter Zijlstra <peterz@infradead.org> - 2016-10-20 07:50 +0200
Re: [4.9-rc1+] intel_uncore builtin + CONFIG_DEBUG_TEST_DRIVER_REMOVE kernel panic Jiri Olsa <jolsa@redhat.com> - 2016-10-20 11:00 +0200
Re: [4.9-rc1+] intel_uncore builtin + CONFIG_DEBUG_TEST_DRIVER_REMOVE kernel panic Peter Zijlstra <peterz@infradead.org> - 2016-10-20 11:10 +0200
Re: [4.9-rc1+] intel_uncore builtin + CONFIG_DEBUG_TEST_DRIVER_REMOVE kernel panic Jiri Olsa <jolsa@redhat.com> - 2016-10-20 11:50 +0200
[PATCH] perf: Protect pmu device removal with pmu_bus_running check CONFIG_DEBUG_TEST_DRIVER_REMOVE kernel panic Jiri Olsa <jolsa@redhat.com> - 2016-10-20 13:20 +0200
Re: [PATCH] perf: Protect pmu device removal with pmu_bus_running check CONFIG_DEBUG_TEST_DRIVER_REMOVE kernel panic CAI Qian <caiqian@redhat.com> - 2016-10-20 16:40 +0200
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