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ARM: 6975/1: pmu: reject duplicate PMU registrations

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Currently, the PMU reservation framework allows for multiple PMUs of
the same type to register themselves. This can lead to a bug with the
sequence:

register_pmu(pmu1);
reserve_pmu(pmu_type);
register_pmu(pmu2);
release_pmu(pmu1);

Here, pmu1 cannot be released, and pmu2 cannot be reserved.

This patch modifies register_pmu to reject registrations where a PMU is
already present, preventing this problem. PMUs which can have multiple
instances should not use the PMU reservation framework.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Jamie Iles <jamie@jamieiles.com>
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This commit is contained in:
Mark Rutland 2011-06-22 15:32:48 +01:00 committed by Russell King
parent f12482c939
commit ae0c3751ab
1 changed files with 6 additions and 6 deletions
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12
arch/arm/kernel/pmu.c
View file

@ -34,13 +34,13 @@ static int __devinit pmu_register(struct platform_device *pdev,
return -EINVAL;
}
if (pmu_devices[type])
pr_warning("registering new PMU device type %d overwrites "
"previous registration!\n", type);
else
pr_info("registered new PMU device of type %d\n",
type);
if (pmu_devices[type]) {
pr_warning("rejecting duplicate registration of PMU device "
"type %d.", type);
return -ENOSPC;
}
pr_info("registered new PMU device of type %d\n", type);
pmu_devices[type] = pdev;
return 0;
}