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coresight: etmv4: Fix CPU power management setup in probe() function

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The current probe() function calls a pair of cpuhp_xxx API functions to
setup CPU hotplug handling. The hotplug lock is held for the duration of
the two calls and other CPU related code using cpus_read_lock() /
cpus_read_unlock() calls.

The problem is that on error states, goto: statements bypass the
cpus_read_unlock() call. This code has increased in complexity as the
driver has developed.

This patch introduces a pair of helper functions etm4_pm_setup_cpuslocked()
and etm4_pm_clear() which correct the issues above and group the PM code a
little better.

The two functions etm4_cpu_pm_register() and etm4_cpu_pm_unregister() are
dropped as these call cpu_pm_register_notifier() / ..unregister_notifier()
dependent on CONFIG_CPU_PM - but this define is used to nop these functions
out in the pm headers - so the wrapper functions are superfluous.

Fixes: f188b5e76a ("coresight: etm4x: Save/restore state across CPU low power states")
Fixes: e9f5d63f84 ("hwtracing/coresight-etm4x: Use cpuhp_setup_state_nocalls_cpuslocked()")
Fixes: 58eb457be0 ("hwtracing/coresight-etm4x: Convert to hotplug state machine")
Signed-off-by: Mike Leach <mike.leach@linaro.org>
Cc: stable <stable@vger.kernel.org>
Reviewed-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Link: https://lore.kernel.org/r/20200701160852.2782823-3-mathieu.poirier@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Mike Leach 2020-07-01 10:08:52 -06:00 committed by Greg Kroah-Hartman
parent 6740de9433
commit 9b6a3f3633
1 changed files with 54 additions and 30 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

84
drivers/hwtracing/coresight/coresight-etm4x.c
View File

@ -1388,18 +1388,57 @@ static struct notifier_block etm4_cpu_pm_nb = {
.notifier_call = etm4_cpu_pm_notify,
};
static int etm4_cpu_pm_register(void)
/* Setup PM. Called with cpus locked. Deals with error conditions and counts */
static int etm4_pm_setup_cpuslocked(void)
{
if (IS_ENABLED(CONFIG_CPU_PM))
return cpu_pm_register_notifier(&etm4_cpu_pm_nb);
int ret;
return 0;
if (etm4_count++)
return 0;
ret = cpu_pm_register_notifier(&etm4_cpu_pm_nb);
if (ret)
goto reduce_count;
ret = cpuhp_setup_state_nocalls_cpuslocked(CPUHP_AP_ARM_CORESIGHT_STARTING,
"arm/coresight4:starting",
etm4_starting_cpu, etm4_dying_cpu);
if (ret)
goto unregister_notifier;
ret = cpuhp_setup_state_nocalls_cpuslocked(CPUHP_AP_ONLINE_DYN,
"arm/coresight4:online",
etm4_online_cpu, NULL);
/* HP dyn state ID returned in ret on success */
if (ret > 0) {
hp_online = ret;
return 0;
}
/* failed dyn state - remove others */
cpuhp_remove_state_nocalls_cpuslocked(CPUHP_AP_ARM_CORESIGHT_STARTING);
unregister_notifier:
cpu_pm_unregister_notifier(&etm4_cpu_pm_nb);
reduce_count:
--etm4_count;
return ret;
}
static void etm4_cpu_pm_unregister(void)
static void etm4_pm_clear(void)
{
if (IS_ENABLED(CONFIG_CPU_PM))
cpu_pm_unregister_notifier(&etm4_cpu_pm_nb);
if (--etm4_count != 0)
return;
cpu_pm_unregister_notifier(&etm4_cpu_pm_nb);
cpuhp_remove_state_nocalls(CPUHP_AP_ARM_CORESIGHT_STARTING);
if (hp_online) {
cpuhp_remove_state_nocalls(hp_online);
hp_online = 0;
}
}
static int etm4_probe(struct amba_device *adev, const struct amba_id *id)
@ -1453,24 +1492,15 @@ static int etm4_probe(struct amba_device *adev, const struct amba_id *id)
etm4_init_arch_data, drvdata, 1))
dev_err(dev, "ETM arch init failed\n");
if (!etm4_count++) {
cpuhp_setup_state_nocalls_cpuslocked(CPUHP_AP_ARM_CORESIGHT_STARTING,
"arm/coresight4:starting",
etm4_starting_cpu, etm4_dying_cpu);
ret = cpuhp_setup_state_nocalls_cpuslocked(CPUHP_AP_ONLINE_DYN,
"arm/coresight4:online",
etm4_online_cpu, NULL);
if (ret < 0)
goto err_arch_supported;
hp_online = ret;
ret = etm4_cpu_pm_register();
if (ret)
goto err_arch_supported;
}
ret = etm4_pm_setup_cpuslocked();
cpus_read_unlock();
/* etm4_pm_setup_cpuslocked() does its own cleanup - exit on error */
if (ret) {
etmdrvdata[drvdata->cpu] = NULL;
return ret;
}
if (etm4_arch_supported(drvdata->arch) == false) {
ret = -EINVAL;
goto err_arch_supported;
@ -1517,13 +1547,7 @@ static int etm4_probe(struct amba_device *adev, const struct amba_id *id)
err_arch_supported:
etmdrvdata[drvdata->cpu] = NULL;
if (--etm4_count == 0) {
etm4_cpu_pm_unregister();
cpuhp_remove_state_nocalls(CPUHP_AP_ARM_CORESIGHT_STARTING);
if (hp_online)
cpuhp_remove_state_nocalls(hp_online);
}
etm4_pm_clear();
return ret;
}