smp_call_function_single() will allocate an IPI interrupt vector to
the target processor and send a function call request to the interrupt
vector. After the target processor receives the IPI interrupt, it will
execute arm_trbe_remove_coresight_cpu() call request in the interrupt
handler.
According to the device_unregister() stack information, if other process
is useing the device, the down_write() may sleep, and trigger deadlocks
or unexpected errors.
arm_trbe_remove_coresight_cpu
coresight_unregister
device_unregister
device_del
kobject_del
__kobject_del
sysfs_remove_dir
kernfs_remove
down_write ---------> it may sleep
Add a helper arm_trbe_disable_cpu() to disable TRBE precpu irq and reset
per TRBE.
Simply call arm_trbe_remove_coresight_cpu() directly without useing the
smp_call_function_single(), which is the same as registering the TRBE
coresight device.
Fixes: 3fbf7f011f24 ("coresight: sink: Add TRBE driver")
Signed-off-by: Junhao He <[email protected]>
---
drivers/hwtracing/coresight/coresight-trbe.c | 35 +++++++++++---------
1 file changed, 20 insertions(+), 15 deletions(-)
diff --git a/drivers/hwtracing/coresight/coresight-trbe.c b/drivers/hwtracing/coresight/coresight-trbe.c
index 7720619909d6..ce1e6f537b8d 100644
--- a/drivers/hwtracing/coresight/coresight-trbe.c
+++ b/drivers/hwtracing/coresight/coresight-trbe.c
@@ -1225,6 +1225,17 @@ static void arm_trbe_enable_cpu(void *info)
enable_percpu_irq(drvdata->irq, IRQ_TYPE_NONE);
}
+static void arm_trbe_disable_cpu(void *info)
+{
+ struct trbe_drvdata *drvdata = info;
+ struct trbe_cpudata *cpudata = this_cpu_ptr(drvdata->cpudata);
+
+ disable_percpu_irq(drvdata->irq);
+ trbe_reset_local(cpudata);
+ cpudata->drvdata = NULL;
+}
+
+
static void arm_trbe_register_coresight_cpu(struct trbe_drvdata *drvdata, int cpu)
{
struct trbe_cpudata *cpudata = per_cpu_ptr(drvdata->cpudata, cpu);
@@ -1326,18 +1337,12 @@ static void arm_trbe_probe_cpu(void *info)
cpumask_clear_cpu(cpu, &drvdata->supported_cpus);
}
-static void arm_trbe_remove_coresight_cpu(void *info)
+static void arm_trbe_remove_coresight_cpu(struct trbe_drvdata *drvdata, int cpu)
{
- int cpu = smp_processor_id();
- struct trbe_drvdata *drvdata = info;
- struct trbe_cpudata *cpudata = per_cpu_ptr(drvdata->cpudata, cpu);
struct coresight_device *trbe_csdev = coresight_get_percpu_sink(cpu);
- disable_percpu_irq(drvdata->irq);
- trbe_reset_local(cpudata);
if (trbe_csdev) {
coresight_unregister(trbe_csdev);
- cpudata->drvdata = NULL;
coresight_set_percpu_sink(cpu, NULL);
}
}
@@ -1366,8 +1371,12 @@ static int arm_trbe_remove_coresight(struct trbe_drvdata *drvdata)
{
int cpu;
- for_each_cpu(cpu, &drvdata->supported_cpus)
- smp_call_function_single(cpu, arm_trbe_remove_coresight_cpu, drvdata, 1);
+ for_each_cpu(cpu, &drvdata->supported_cpus) {
+ if (cpumask_test_cpu(cpu, &drvdata->supported_cpus))
+ smp_call_function_single(cpu, arm_trbe_disable_cpu, drvdata, 1);
+ if (cpumask_test_cpu(cpu, &drvdata->supported_cpus))
+ arm_trbe_remove_coresight_cpu(drvdata, cpu);
+ }
free_percpu(drvdata->cpudata);
return 0;
}
@@ -1406,12 +1415,8 @@ static int arm_trbe_cpu_teardown(unsigned int cpu, struct hlist_node *node)
{
struct trbe_drvdata *drvdata = hlist_entry_safe(node, struct trbe_drvdata, hotplug_node);
- if (cpumask_test_cpu(cpu, &drvdata->supported_cpus)) {
- struct trbe_cpudata *cpudata = per_cpu_ptr(drvdata->cpudata, cpu);
-
- disable_percpu_irq(drvdata->irq);
- trbe_reset_local(cpudata);
- }
+ if (cpumask_test_cpu(cpu, &drvdata->supported_cpus))
+ arm_trbe_disable_cpu(drvdata);
return 0;
}
--
2.33.0
Hi Junhao
On 14/08/2023 10:38, Junhao He wrote:
> smp_call_function_single() will allocate an IPI interrupt vector to
> the target processor and send a function call request to the interrupt
> vector. After the target processor receives the IPI interrupt, it will
> execute arm_trbe_remove_coresight_cpu() call request in the interrupt
> handler.
>
> According to the device_unregister() stack information, if other process
> is useing the device, the down_write() may sleep, and trigger deadlocks
> or unexpected errors.
>
> arm_trbe_remove_coresight_cpu
> coresight_unregister
> device_unregister
> device_del
> kobject_del
> __kobject_del
> sysfs_remove_dir
> kernfs_remove
> down_write ---------> it may sleep
>
> Add a helper arm_trbe_disable_cpu() to disable TRBE precpu irq and reset
> per TRBE.
> Simply call arm_trbe_remove_coresight_cpu() directly without useing the
> smp_call_function_single(), which is the same as registering the TRBE
> coresight device.
>
> Fixes: 3fbf7f011f24 ("coresight: sink: Add TRBE driver")
> Signed-off-by: Junhao He <[email protected]>
> ---
> drivers/hwtracing/coresight/coresight-trbe.c | 35 +++++++++++---------
> 1 file changed, 20 insertions(+), 15 deletions(-)
>
> diff --git a/drivers/hwtracing/coresight/coresight-trbe.c b/drivers/hwtracing/coresight/coresight-trbe.c
> index 7720619909d6..ce1e6f537b8d 100644
> --- a/drivers/hwtracing/coresight/coresight-trbe.c
> +++ b/drivers/hwtracing/coresight/coresight-trbe.c
> @@ -1225,6 +1225,17 @@ static void arm_trbe_enable_cpu(void *info)
> enable_percpu_irq(drvdata->irq, IRQ_TYPE_NONE);
> }
>
> +static void arm_trbe_disable_cpu(void *info)
> +{
> + struct trbe_drvdata *drvdata = info;
> + struct trbe_cpudata *cpudata = this_cpu_ptr(drvdata->cpudata);
> +
> + disable_percpu_irq(drvdata->irq);
> + trbe_reset_local(cpudata);
> + cpudata->drvdata = NULL;
> +}
> +
> +
> static void arm_trbe_register_coresight_cpu(struct trbe_drvdata *drvdata, int cpu)
> {
> struct trbe_cpudata *cpudata = per_cpu_ptr(drvdata->cpudata, cpu);
> @@ -1326,18 +1337,12 @@ static void arm_trbe_probe_cpu(void *info)
> cpumask_clear_cpu(cpu, &drvdata->supported_cpus);
> }
>
> -static void arm_trbe_remove_coresight_cpu(void *info)
> +static void arm_trbe_remove_coresight_cpu(struct trbe_drvdata *drvdata, int cpu)
> {
> - int cpu = smp_processor_id();
> - struct trbe_drvdata *drvdata = info;
> - struct trbe_cpudata *cpudata = per_cpu_ptr(drvdata->cpudata, cpu);
> struct coresight_device *trbe_csdev = coresight_get_percpu_sink(cpu);
>
> - disable_percpu_irq(drvdata->irq);
> - trbe_reset_local(cpudata);
> if (trbe_csdev) {
> coresight_unregister(trbe_csdev);
> - cpudata->drvdata = NULL;
> coresight_set_percpu_sink(cpu, NULL);
I am a bit concerned about "resetting" the sink from a different CPU.
Could we instead, schedule a delayed work to unregister the trbe_csdev?
Suzuki
> }
> }
> @@ -1366,8 +1371,12 @@ static int arm_trbe_remove_coresight(struct trbe_drvdata *drvdata)
> {
> int cpu;
>
> - for_each_cpu(cpu, &drvdata->supported_cpus)
> - smp_call_function_single(cpu, arm_trbe_remove_coresight_cpu, drvdata, 1);
> + for_each_cpu(cpu, &drvdata->supported_cpus) {
> + if (cpumask_test_cpu(cpu, &drvdata->supported_cpus))
> + smp_call_function_single(cpu, arm_trbe_disable_cpu, drvdata, 1);
> + if (cpumask_test_cpu(cpu, &drvdata->supported_cpus))
> + arm_trbe_remove_coresight_cpu(drvdata, cpu);
> + }
> free_percpu(drvdata->cpudata);
> return 0;
> }
> @@ -1406,12 +1415,8 @@ static int arm_trbe_cpu_teardown(unsigned int cpu, struct hlist_node *node)
> {
> struct trbe_drvdata *drvdata = hlist_entry_safe(node, struct trbe_drvdata, hotplug_node);
>
> - if (cpumask_test_cpu(cpu, &drvdata->supported_cpus)) {
> - struct trbe_cpudata *cpudata = per_cpu_ptr(drvdata->cpudata, cpu);
> -
> - disable_percpu_irq(drvdata->irq);
> - trbe_reset_local(cpudata);
> - }
> + if (cpumask_test_cpu(cpu, &drvdata->supported_cpus))
> + arm_trbe_disable_cpu(drvdata);
> return 0;
> }
>
Hi Suzuki
On 2023/8/14 18:34, Suzuki K Poulose wrote:
> Hi Junhao
>
> On 14/08/2023 10:38, Junhao He wrote:
>> smp_call_function_single() will allocate an IPI interrupt vector to
>> the target processor and send a function call request to the interrupt
>> vector. After the target processor receives the IPI interrupt, it will
>> execute arm_trbe_remove_coresight_cpu() call request in the interrupt
>> handler.
>>
>> According to the device_unregister() stack information, if other process
>> is useing the device, the down_write() may sleep, and trigger deadlocks
>> or unexpected errors.
>>
>> arm_trbe_remove_coresight_cpu
>> coresight_unregister
>> device_unregister
>> device_del
>> kobject_del
>> __kobject_del
>> sysfs_remove_dir
>> kernfs_remove
>> down_write ---------> it may sleep
>>
>> Add a helper arm_trbe_disable_cpu() to disable TRBE precpu irq and reset
>> per TRBE.
>> Simply call arm_trbe_remove_coresight_cpu() directly without useing the
>> smp_call_function_single(), which is the same as registering the TRBE
>> coresight device.
>>
>> Fixes: 3fbf7f011f24 ("coresight: sink: Add TRBE driver")
>> Signed-off-by: Junhao He <[email protected]>
>> ---
>> drivers/hwtracing/coresight/coresight-trbe.c | 35 +++++++++++---------
>> 1 file changed, 20 insertions(+), 15 deletions(-)
>>
>> diff --git a/drivers/hwtracing/coresight/coresight-trbe.c
>> b/drivers/hwtracing/coresight/coresight-trbe.c
>> index 7720619909d6..ce1e6f537b8d 100644
>> --- a/drivers/hwtracing/coresight/coresight-trbe.c
>> +++ b/drivers/hwtracing/coresight/coresight-trbe.c
>> @@ -1225,6 +1225,17 @@ static void arm_trbe_enable_cpu(void *info)
>> enable_percpu_irq(drvdata->irq, IRQ_TYPE_NONE);
>> }
>> +static void arm_trbe_disable_cpu(void *info)
>> +{
>> + struct trbe_drvdata *drvdata = info;
>> + struct trbe_cpudata *cpudata = this_cpu_ptr(drvdata->cpudata);
>> +
>> + disable_percpu_irq(drvdata->irq);
>> + trbe_reset_local(cpudata);
>> + cpudata->drvdata = NULL;
>> +}
>> +
>> +
>> static void arm_trbe_register_coresight_cpu(struct trbe_drvdata
>> *drvdata, int cpu)
>> {
>> struct trbe_cpudata *cpudata = per_cpu_ptr(drvdata->cpudata, cpu);
>> @@ -1326,18 +1337,12 @@ static void arm_trbe_probe_cpu(void *info)
>> cpumask_clear_cpu(cpu, &drvdata->supported_cpus);
>> }
>> -static void arm_trbe_remove_coresight_cpu(void *info)
>> +static void arm_trbe_remove_coresight_cpu(struct trbe_drvdata
>> *drvdata, int cpu)
>> {
>> - int cpu = smp_processor_id();
>> - struct trbe_drvdata *drvdata = info;
>> - struct trbe_cpudata *cpudata = per_cpu_ptr(drvdata->cpudata, cpu);
>> struct coresight_device *trbe_csdev =
>> coresight_get_percpu_sink(cpu);
>> - disable_percpu_irq(drvdata->irq);
>> - trbe_reset_local(cpudata);
>> if (trbe_csdev) {
>> coresight_unregister(trbe_csdev);
>> - cpudata->drvdata = NULL;
>> coresight_set_percpu_sink(cpu, NULL);
>
> I am a bit concerned about "resetting" the sink from a different CPU.
> Could we instead, schedule a delayed work to unregister the trbe_csdev?
Yes, I will try to do that.
Sorry for my following questions.
As you mean, do we need to take the same care when setting the percpu sink
in the register trbe_csdev ?
Best regards,
Junhao.
>
>
>> }
>> }
>> @@ -1366,8 +1371,12 @@ static int arm_trbe_remove_coresight(struct
>> trbe_drvdata *drvdata)
>> {
>> int cpu;
>> - for_each_cpu(cpu, &drvdata->supported_cpus)
>> - smp_call_function_single(cpu, arm_trbe_remove_coresight_cpu,
>> drvdata, 1);
>> + for_each_cpu(cpu, &drvdata->supported_cpus) {
>> + if (cpumask_test_cpu(cpu, &drvdata->supported_cpus))
>> + smp_call_function_single(cpu, arm_trbe_disable_cpu,
>> drvdata, 1);
>> + if (cpumask_test_cpu(cpu, &drvdata->supported_cpus))
>> + arm_trbe_remove_coresight_cpu(drvdata, cpu);
>> + }
>> free_percpu(drvdata->cpudata);
>> return 0;
>> }
>> @@ -1406,12 +1415,8 @@ static int arm_trbe_cpu_teardown(unsigned int
>> cpu, struct hlist_node *node)
>> {
>> struct trbe_drvdata *drvdata = hlist_entry_safe(node, struct
>> trbe_drvdata, hotplug_node);
>> - if (cpumask_test_cpu(cpu, &drvdata->supported_cpus)) {
>> - struct trbe_cpudata *cpudata = per_cpu_ptr(drvdata->cpudata,
>> cpu);
>> -
>> - disable_percpu_irq(drvdata->irq);
>> - trbe_reset_local(cpudata);
>> - }
>> + if (cpumask_test_cpu(cpu, &drvdata->supported_cpus))
>> + arm_trbe_disable_cpu(drvdata);
>> return 0;
>> }
>
>
> .
>
On 14/08/2023 14:32, hejunhao wrote:
> Hi Suzuki
>
>
> On 2023/8/14 18:34, Suzuki K Poulose wrote:
>> Hi Junhao
>>
>> On 14/08/2023 10:38, Junhao He wrote:
>>> smp_call_function_single() will allocate an IPI interrupt vector to
>>> the target processor and send a function call request to the interrupt
>>> vector. After the target processor receives the IPI interrupt, it will
>>> execute arm_trbe_remove_coresight_cpu() call request in the interrupt
>>> handler.
>>>
>>> According to the device_unregister() stack information, if other process
>>> is useing the device, the down_write() may sleep, and trigger deadlocks
>>> or unexpected errors.
>>>
>>> arm_trbe_remove_coresight_cpu
>>> coresight_unregister
>>> device_unregister
>>> device_del
>>> kobject_del
>>> __kobject_del
>>> sysfs_remove_dir
>>> kernfs_remove
>>> down_write ---------> it may sleep
>>>
>>> Add a helper arm_trbe_disable_cpu() to disable TRBE precpu irq and reset
>>> per TRBE.
>>> Simply call arm_trbe_remove_coresight_cpu() directly without useing the
>>> smp_call_function_single(), which is the same as registering the TRBE
>>> coresight device.
>>>
>>> Fixes: 3fbf7f011f24 ("coresight: sink: Add TRBE driver")
>>> Signed-off-by: Junhao He <[email protected]>
>>> ---
>>> drivers/hwtracing/coresight/coresight-trbe.c | 35 +++++++++++---------
>>> 1 file changed, 20 insertions(+), 15 deletions(-)
>>>
>>> diff --git a/drivers/hwtracing/coresight/coresight-trbe.c
>>> b/drivers/hwtracing/coresight/coresight-trbe.c
>>> index 7720619909d6..ce1e6f537b8d 100644
>>> --- a/drivers/hwtracing/coresight/coresight-trbe.c
>>> +++ b/drivers/hwtracing/coresight/coresight-trbe.c
>>> @@ -1225,6 +1225,17 @@ static void arm_trbe_enable_cpu(void *info)
>>> enable_percpu_irq(drvdata->irq, IRQ_TYPE_NONE);
>>> }
>>> +static void arm_trbe_disable_cpu(void *info)
>>> +{
>>> + struct trbe_drvdata *drvdata = info;
>>> + struct trbe_cpudata *cpudata = this_cpu_ptr(drvdata->cpudata);
>>> +
>>> + disable_percpu_irq(drvdata->irq);
>>> + trbe_reset_local(cpudata);
>>> + cpudata->drvdata = NULL;
>>> +}
>>> +
>>> +
>>> static void arm_trbe_register_coresight_cpu(struct trbe_drvdata
>>> *drvdata, int cpu)
>>> {
>>> struct trbe_cpudata *cpudata = per_cpu_ptr(drvdata->cpudata, cpu);
>>> @@ -1326,18 +1337,12 @@ static void arm_trbe_probe_cpu(void *info)
>>> cpumask_clear_cpu(cpu, &drvdata->supported_cpus);
>>> }
>>> -static void arm_trbe_remove_coresight_cpu(void *info)
>>> +static void arm_trbe_remove_coresight_cpu(struct trbe_drvdata
>>> *drvdata, int cpu)
>>> {
>>> - int cpu = smp_processor_id();
>>> - struct trbe_drvdata *drvdata = info;
>>> - struct trbe_cpudata *cpudata = per_cpu_ptr(drvdata->cpudata, cpu);
>>> struct coresight_device *trbe_csdev =
>>> coresight_get_percpu_sink(cpu);
>>> - disable_percpu_irq(drvdata->irq);
>>> - trbe_reset_local(cpudata);
>>> if (trbe_csdev) {
>>> coresight_unregister(trbe_csdev);
>>> - cpudata->drvdata = NULL;
>>> coresight_set_percpu_sink(cpu, NULL);
>>
>> I am a bit concerned about "resetting" the sink from a different CPU.
>> Could we instead, schedule a delayed work to unregister the trbe_csdev?
>
> Yes, I will try to do that.
> Sorry for my following questions.
> As you mean, do we need to take the same care when setting the percpu sink
> in the register trbe_csdev ?
Apologies, having taken another look, we set the percpu_sink for
a cpu outside smp_call_function(). So, I think your patch is fine.
>
> Best regards,
> Junhao.
>
>>
>>
>>> }
>>> }
>>> @@ -1366,8 +1371,12 @@ static int arm_trbe_remove_coresight(struct
>>> trbe_drvdata *drvdata)
>>> {
>>> int cpu;
>>> - for_each_cpu(cpu, &drvdata->supported_cpus)
>>> - smp_call_function_single(cpu, arm_trbe_remove_coresight_cpu,
>>> drvdata, 1);
>>> + for_each_cpu(cpu, &drvdata->supported_cpus) {
>>> + if (cpumask_test_cpu(cpu, &drvdata->supported_cpus))
>>> + smp_call_function_single(cpu, arm_trbe_disable_cpu,
>>> drvdata, 1);
>>> + if (cpumask_test_cpu(cpu, &drvdata->supported_cpus))
>>> + arm_trbe_remove_coresight_cpu(drvdata, cpu);
Do we need to test the cpu here in both places ? We already check that
in the loop entry. The reason why we repeat the check during the probe,
is to skip any CPUs that may have a TRBE not accessible.
Suzuki
>>> + }
>>> free_percpu(drvdata->cpudata);
>>> return 0;
>>> }
>>> @@ -1406,12 +1415,8 @@ static int arm_trbe_cpu_teardown(unsigned int
>>> cpu, struct hlist_node *node)
>>> {
>>> struct trbe_drvdata *drvdata = hlist_entry_safe(node, struct
>>> trbe_drvdata, hotplug_node);
>>> - if (cpumask_test_cpu(cpu, &drvdata->supported_cpus)) {
>>> - struct trbe_cpudata *cpudata = per_cpu_ptr(drvdata->cpudata,
>>> cpu);
>>> -
>>> - disable_percpu_irq(drvdata->irq);
>>> - trbe_reset_local(cpudata);
>>> - }
>>> + if (cpumask_test_cpu(cpu, &drvdata->supported_cpus))
>>> + arm_trbe_disable_cpu(drvdata);
>>> return 0;
>>> }
>>
>>
>> .
>>
>
Hi Suzuki
On 2023/8/15 6:57, Suzuki K Poulose wrote:
> On 14/08/2023 14:32, hejunhao wrote:
>> Hi Suzuki
>>
>>
>> On 2023/8/14 18:34, Suzuki K Poulose wrote:
>>> Hi Junhao
>>>
>>> On 14/08/2023 10:38, Junhao He wrote:
>>>> smp_call_function_single() will allocate an IPI interrupt vector to
>>>> the target processor and send a function call request to the interrupt
>>>> vector. After the target processor receives the IPI interrupt, it will
>>>> execute arm_trbe_remove_coresight_cpu() call request in the interrupt
>>>> handler.
>>>>
>>>> According to the device_unregister() stack information, if other
>>>> process
>>>> is useing the device, the down_write() may sleep, and trigger
>>>> deadlocks
>>>> or unexpected errors.
>>>>
>>>> arm_trbe_remove_coresight_cpu
>>>> coresight_unregister
>>>> device_unregister
>>>> device_del
>>>> kobject_del
>>>> __kobject_del
>>>> sysfs_remove_dir
>>>> kernfs_remove
>>>> down_write ---------> it may sleep
>>>>
>>>> Add a helper arm_trbe_disable_cpu() to disable TRBE precpu irq and
>>>> reset
>>>> per TRBE.
>>>> Simply call arm_trbe_remove_coresight_cpu() directly without useing
>>>> the
>>>> smp_call_function_single(), which is the same as registering the TRBE
>>>> coresight device.
>>>>
>>>> Fixes: 3fbf7f011f24 ("coresight: sink: Add TRBE driver")
>>>> Signed-off-by: Junhao He <[email protected]>
>>>> ---
>>>> drivers/hwtracing/coresight/coresight-trbe.c | 35
>>>> +++++++++++---------
>>>> 1 file changed, 20 insertions(+), 15 deletions(-)
>>>>
>>>> diff --git a/drivers/hwtracing/coresight/coresight-trbe.c
>>>> b/drivers/hwtracing/coresight/coresight-trbe.c
>>>> index 7720619909d6..ce1e6f537b8d 100644
>>>> --- a/drivers/hwtracing/coresight/coresight-trbe.c
>>>> +++ b/drivers/hwtracing/coresight/coresight-trbe.c
>>>> @@ -1225,6 +1225,17 @@ static void arm_trbe_enable_cpu(void *info)
>>>> enable_percpu_irq(drvdata->irq, IRQ_TYPE_NONE);
>>>> }
>>>> +static void arm_trbe_disable_cpu(void *info)
>>>> +{
>>>> + struct trbe_drvdata *drvdata = info;
>>>> + struct trbe_cpudata *cpudata = this_cpu_ptr(drvdata->cpudata);
>>>> +
>>>> + disable_percpu_irq(drvdata->irq);
>>>> + trbe_reset_local(cpudata);
>>>> + cpudata->drvdata = NULL;
>>>> +}
>>>> +
>>>> +
>>>> static void arm_trbe_register_coresight_cpu(struct trbe_drvdata
>>>> *drvdata, int cpu)
>>>> {
>>>> struct trbe_cpudata *cpudata = per_cpu_ptr(drvdata->cpudata,
>>>> cpu);
>>>> @@ -1326,18 +1337,12 @@ static void arm_trbe_probe_cpu(void *info)
>>>> cpumask_clear_cpu(cpu, &drvdata->supported_cpus);
>>>> }
>>>> -static void arm_trbe_remove_coresight_cpu(void *info)
>>>> +static void arm_trbe_remove_coresight_cpu(struct trbe_drvdata
>>>> *drvdata, int cpu)
>>>> {
>>>> - int cpu = smp_processor_id();
>>>> - struct trbe_drvdata *drvdata = info;
>>>> - struct trbe_cpudata *cpudata = per_cpu_ptr(drvdata->cpudata,
>>>> cpu);
>>>> struct coresight_device *trbe_csdev =
>>>> coresight_get_percpu_sink(cpu);
>>>> - disable_percpu_irq(drvdata->irq);
>>>> - trbe_reset_local(cpudata);
>>>> if (trbe_csdev) {
>>>> coresight_unregister(trbe_csdev);
>>>> - cpudata->drvdata = NULL;
>>>> coresight_set_percpu_sink(cpu, NULL);
>>>
>>> I am a bit concerned about "resetting" the sink from a different CPU.
>>> Could we instead, schedule a delayed work to unregister the trbe_csdev?
>>
>> Yes, I will try to do that.
>> Sorry for my following questions.
>> As you mean, do we need to take the same care when setting the percpu
>> sink
>> in the register trbe_csdev ?
>
> Apologies, having taken another look, we set the percpu_sink for
> a cpu outside smp_call_function(). So, I think your patch is fine.
>
>
>>
>> Best regards,
>> Junhao.
>>
>>>
>>>
>>>> }
>>>> }
>>>> @@ -1366,8 +1371,12 @@ static int arm_trbe_remove_coresight(struct
>>>> trbe_drvdata *drvdata)
>>>> {
>>>> int cpu;
>>>> - for_each_cpu(cpu, &drvdata->supported_cpus)
>>>> - smp_call_function_single(cpu,
>>>> arm_trbe_remove_coresight_cpu, drvdata, 1);
>>>> + for_each_cpu(cpu, &drvdata->supported_cpus) {
>>>> + if (cpumask_test_cpu(cpu, &drvdata->supported_cpus))
>>>> + smp_call_function_single(cpu, arm_trbe_disable_cpu,
>>>> drvdata, 1);
>>>> + if (cpumask_test_cpu(cpu, &drvdata->supported_cpus))
>>>> + arm_trbe_remove_coresight_cpu(drvdata, cpu);
>
> Do we need to test the cpu here in both places ? We already check that
> in the loop entry. The reason why we repeat the check during the probe,
> is to skip any CPUs that may have a TRBE not accessible.
>
> Suzuki
>
Ok, Will fix in next version.
Best regards,
Junhao.
>
>>>> + }
>>>> free_percpu(drvdata->cpudata);
>>>> return 0;
>>>> }
>>>> @@ -1406,12 +1415,8 @@ static int arm_trbe_cpu_teardown(unsigned
>>>> int cpu, struct hlist_node *node)
>>>> {
>>>> struct trbe_drvdata *drvdata = hlist_entry_safe(node, struct
>>>> trbe_drvdata, hotplug_node);
>>>> - if (cpumask_test_cpu(cpu, &drvdata->supported_cpus)) {
>>>> - struct trbe_cpudata *cpudata =
>>>> per_cpu_ptr(drvdata->cpudata, cpu);
>>>> -
>>>> - disable_percpu_irq(drvdata->irq);
>>>> - trbe_reset_local(cpudata);
>>>> - }
>>>> + if (cpumask_test_cpu(cpu, &drvdata->supported_cpus))
>>>> + arm_trbe_disable_cpu(drvdata);
>>>> return 0;
>>>> }
>>>
>>>
>>> .
>>>
>>
>
>
> .
>