From: Peter Zijlstra <peterz@infradead.org>
To: Jiri Olsa <jolsa@redhat.com>
Cc: CAI Qian <caiqian@redhat.com>, Rob Herring <robh@kernel.org>,
Kan Liang <kan.liang@intel.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
linux-kernel <linux-kernel@vger.kernel.org>,
Ingo Molnar <mingo@kernel.org>
Subject: Re: [4.9-rc1+] intel_uncore builtin + CONFIG_DEBUG_TEST_DRIVER_REMOVE kernel panic
Date: Thu, 20 Oct 2016 11:04:16 +0200 [thread overview]
Message-ID: <20161020090416.GS3102@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <20161020085803.GA31721@krava>
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 */
/* 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.
next prev parent reply other threads:[~2016-10-20 9:04 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <907882571.66590.1476113724660.JavaMail.zimbra@redhat.com>
2016-10-10 15:37 ` kasan inline + CONFIG_DEBUG_TEST_DRIVER_REMOVE kernel panic CAI Qian
2016-10-10 17:09 ` Rob Herring
2016-10-10 18:25 ` CAI Qian
2016-10-10 17:20 ` Greg Kroah-Hartman
2016-10-10 18:15 ` Rob Herring
2016-10-10 18:22 ` CAI Qian
2016-10-10 19:34 ` Rob Herring
2016-10-10 20:09 ` CAI Qian
2016-10-19 14:45 ` [4.9-rc1+] intel_uncore builtin " CAI Qian
2016-10-19 19:19 ` Jiri Olsa
2016-10-19 20:18 ` CAI Qian
2016-10-20 5:39 ` Peter Zijlstra
2016-10-20 8:58 ` Jiri Olsa
2016-10-20 9:04 ` Peter Zijlstra [this message]
2016-10-20 9:42 ` Jiri Olsa
2016-10-20 11:10 ` [PATCH] perf: Protect pmu device removal with pmu_bus_running check " Jiri Olsa
2016-10-20 14:30 ` CAI Qian
2016-10-28 10:10 ` [tip:perf/urgent] perf/core: Protect PMU device removal with a 'pmu_bus_running' check, to fix CONFIG_DEBUG_TEST_DRIVER_REMOVE=y " tip-bot for Jiri Olsa
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