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Revision 0933840acf7b65d6d30a5b6089d882afea57aca3 authored by Jiri Olsa on 20 October 2016, 11:10:11 UTC, committed by Ingo Molnar on 28 October 2016, 09:06:25 UTC 
perf/core: Protect PMU device removal with a 'pmu_bus_running' check, to fix CONFIG_DEBUG_TEST_DRIVER_REMOVE=y kernel panic
 
CAI Qian reported a crash in the PMU uncore device removal code,
enabled by the CONFIG_DEBUG_TEST_DRIVER_REMOVE=y option:

  https://marc.info/?l=linux-kernel&m=147688837328451

The reason for the crash is that perf_pmu_unregister() tries to remove
a PMU device which is not added at this point. We add PMU devices
only after pmu_bus is registered, which happens in the
perf_event_sysfs_init() call and sets the 'pmu_bus_running' flag.

The fix is to get the 'pmu_bus_running' flag state at the point
the PMU is taken out of the PMU list and remove the device
later only if it's set.

Reported-by: CAI Qian <caiqian@redhat.com>
Tested-by: CAI Qian <caiqian@redhat.com>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Kan Liang <kan.liang@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rob Herring <robh@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20161020111011.GA13361@krava
Signed-off-by: Ingo Molnar <mingo@kernel.org>
1 parent 889882b
Raw File
rtc-generic.c 
/* rtc-generic: RTC driver using the generic RTC abstraction
 *
 * Copyright (C) 2008 Kyle McMartin <kyle@mcmartin.ca>
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/time.h>
#include <linux/platform_device.h>
#include <linux/rtc.h>

static int __init generic_rtc_probe(struct platform_device *dev)
{
	struct rtc_device *rtc;
	const struct rtc_class_ops *ops = dev_get_platdata(&dev->dev);

	rtc = devm_rtc_device_register(&dev->dev, "rtc-generic",
					ops, THIS_MODULE);
	if (IS_ERR(rtc))
		return PTR_ERR(rtc);

	platform_set_drvdata(dev, rtc);

	return 0;
}

static struct platform_driver generic_rtc_driver = {
	.driver = {
		.name = "rtc-generic",
	},
};

module_platform_driver_probe(generic_rtc_driver, generic_rtc_probe);

MODULE_AUTHOR("Kyle McMartin <kyle@mcmartin.ca>");
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Generic RTC driver");
MODULE_ALIAS("platform:rtc-generic");
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