* [PATCH] coresight: etmv4: Fix CPU power management setup in probe() function.
@ 2020-06-23 20:46 Mike Leach
2020-06-29 20:36 ` Mathieu Poirier
0 siblings, 1 reply; 2+ messages in thread
From: Mike Leach @ 2020-06-23 20:46 UTC (permalink / raw)
To: linux-arm-kernel, coresight, mathieu.poirier; +Cc: Mike Leach, suzuki.poulose
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() 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: f188b5e76aae ("coresight: etm4x: Save/restore state across CPU low power states")
Fixes: e9f5d63f84fe ("hwtracing/coresight-etm4x: Use cpuhp_setup_state_nocalls_cpuslocked()")
Fixes: 58eb457be028 ("etm4x: Convert to hotplug state machine")
Signed-off-by: Mike Leach <mike.leach@linaro.org>
---
drivers/hwtracing/coresight/coresight-etm4x.c | 79 ++++++++++++-------
1 file changed, 51 insertions(+), 28 deletions(-)
diff --git a/drivers/hwtracing/coresight/coresight-etm4x.c b/drivers/hwtracing/coresight/coresight-etm4x.c
index 919b76fa49c4..4dd59de440de 100644
--- a/drivers/hwtracing/coresight/coresight-etm4x.c
+++ b/drivers/hwtracing/coresight/coresight-etm4x.c
@@ -1407,18 +1407,56 @@ 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))
+ if (--etm4_count == 0) {
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)
@@ -1475,24 +1513,15 @@ 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_pm_setup_cpuslocked();
+ cpus_read_unlock();
- ret = etm4_cpu_pm_register();
- if (ret)
- goto err_arch_supported;
+ /* etm4_pm_setup does its own cleanup - just exit on error here */
+ if (ret) {
+ etmdrvdata[drvdata->cpu] = NULL;
+ return ret;
}
- cpus_read_unlock();
-
if (etm4_arch_supported(drvdata->arch) == false) {
ret = -EINVAL;
goto err_arch_supported;
@@ -1544,13 +1573,7 @@ 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;
}
--
2.17.1
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^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] coresight: etmv4: Fix CPU power management setup in probe() function.
2020-06-23 20:46 [PATCH] coresight: etmv4: Fix CPU power management setup in probe() function Mike Leach
@ 2020-06-29 20:36 ` Mathieu Poirier
0 siblings, 0 replies; 2+ messages in thread
From: Mathieu Poirier @ 2020-06-29 20:36 UTC (permalink / raw)
To: Mike Leach; +Cc: coresight, linux-arm-kernel, suzuki.poulose
Hi Mike,
On Tue, Jun 23, 2020 at 09:46:06PM +0100, Mike Leach wrote:
> 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() 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: f188b5e76aae ("coresight: etm4x: Save/restore state across CPU low power states")
> Fixes: e9f5d63f84fe ("hwtracing/coresight-etm4x: Use cpuhp_setup_state_nocalls_cpuslocked()")
> Fixes: 58eb457be028 ("etm4x: Convert to hotplug state machine")
>
> Signed-off-by: Mike Leach <mike.leach@linaro.org>
> ---
> drivers/hwtracing/coresight/coresight-etm4x.c | 79 ++++++++++++-------
> 1 file changed, 51 insertions(+), 28 deletions(-)
>
> diff --git a/drivers/hwtracing/coresight/coresight-etm4x.c b/drivers/hwtracing/coresight/coresight-etm4x.c
> index 919b76fa49c4..4dd59de440de 100644
> --- a/drivers/hwtracing/coresight/coresight-etm4x.c
> +++ b/drivers/hwtracing/coresight/coresight-etm4x.c
> @@ -1407,18 +1407,56 @@ 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);
The 80 character limit per line has been relaxed to 100 in the 5.8 cycle. As
such you can arrange CPUHP_AP_ARM_CORESIGHT_STARTING the same way you did below
with CPUHP_AP_ONLINE_DYN without getting yelled at by checkpatch.
> +
> + 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))
> + if (--etm4_count == 0) {
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)
> @@ -1475,24 +1513,15 @@ 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_pm_setup_cpuslocked();
> + cpus_read_unlock();
>
> - ret = etm4_cpu_pm_register();
> - if (ret)
> - goto err_arch_supported;
> + /* etm4_pm_setup does its own cleanup - just exit on error here */
s/etm4_pm_setup/etm4_pm_setup_cpuslocked()
Otherwise this is a good cleanup.
Thanks,
Mathieu
> + if (ret) {
> + etmdrvdata[drvdata->cpu] = NULL;
> + return ret;
> }
>
> - cpus_read_unlock();
> -
> if (etm4_arch_supported(drvdata->arch) == false) {
> ret = -EINVAL;
> goto err_arch_supported;
> @@ -1544,13 +1573,7 @@ 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;
> }
>
> --
> 2.17.1
>
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2020-06-23 20:46 [PATCH] coresight: etmv4: Fix CPU power management setup in probe() function Mike Leach
2020-06-29 20:36 ` Mathieu Poirier
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