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    Subject[PATCH 5.15 242/846] perf/arm-cmn: Fix CPU hotplug unregistration
    Date
    From: Robin Murphy <robin.murphy@arm.com>

    [ Upstream commit 56c7c6eaf3eb8ac1ec40d56096c0f2b27250da5f ]

    Attempting to migrate the PMU context after we've unregistered the PMU
    device, or especially if we never successfully registered it in the
    first place, is a woefully bad idea. It's also fundamentally pointless
    anyway. Make sure to unregister an instance from the hotplug handler
    *without* invoking the teardown callback.

    Fixes: 0ba64770a2f2 ("perf: Add Arm CMN-600 PMU driver")
    Signed-off-by: Robin Murphy <robin.murphy@arm.com>
    Link: https://lore.kernel.org/r/2c221d745544774e4b07583b65b5d4d94f7e0fe4.1638530442.git.robin.murphy@arm.com
    Signed-off-by: Will Deacon <will@kernel.org>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    drivers/perf/arm-cmn.c | 5 +++--
    1 file changed, 3 insertions(+), 2 deletions(-)

    diff --git a/drivers/perf/arm-cmn.c b/drivers/perf/arm-cmn.c
    index bc3cba5f8c5dc..400eb7f579dce 100644
    --- a/drivers/perf/arm-cmn.c
    +++ b/drivers/perf/arm-cmn.c
    @@ -1561,7 +1561,8 @@ static int arm_cmn_probe(struct platform_device *pdev)

    err = perf_pmu_register(&cmn->pmu, name, -1);
    if (err)
    - cpuhp_state_remove_instance(arm_cmn_hp_state, &cmn->cpuhp_node);
    + cpuhp_state_remove_instance_nocalls(arm_cmn_hp_state, &cmn->cpuhp_node);
    +
    return err;
    }

    @@ -1572,7 +1573,7 @@ static int arm_cmn_remove(struct platform_device *pdev)
    writel_relaxed(0, cmn->dtc[0].base + CMN_DT_DTC_CTL);

    perf_pmu_unregister(&cmn->pmu);
    - cpuhp_state_remove_instance(arm_cmn_hp_state, &cmn->cpuhp_node);
    + cpuhp_state_remove_instance_nocalls(arm_cmn_hp_state, &cmn->cpuhp_node);
    return 0;
    }

    --
    2.34.1


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