[1/4] coresight: tmc-etr: Do not call smp_processor_id() from preemptible
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Message ID 1557480663-16759-2-git-send-email-suzuki.poulose@arm.com
State Superseded
Headers show
Series
  • coresight: Do not call smp_processor_id from preemptible contexts
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Commit Message

Suzuki K Poulose May 10, 2019, 9:31 a.m. UTC
Instead of using smp_processor_id() to figure out the node,
use the numa_node_id() for the current CPU node to avoid
splats like :

 BUG: using smp_processor_id() in preemptible [00000000] code: perf/1743
 caller is alloc_etr_buf.isra.6+0x80/0xa0
 CPU: 1 PID: 1743 Comm: perf Not tainted 5.1.0-rc6-147786-g116841e #344
 Hardware name: ARM LTD ARM Juno Development Platform/ARM Juno Development Platform, BIOS EDK II Feb  1 2019
  Call trace:
   dump_backtrace+0x0/0x150
   show_stack+0x14/0x20
   dump_stack+0x9c/0xc4
   debug_smp_processor_id+0x10c/0x110
   alloc_etr_buf.isra.6+0x80/0xa0
   tmc_alloc_etr_buffer+0x12c/0x1f0
   etm_setup_aux+0x1c4/0x230
   rb_alloc_aux+0x1b8/0x2b8
   perf_mmap+0x35c/0x478
   mmap_region+0x34c/0x4f0
   do_mmap+0x2d8/0x418
   vm_mmap_pgoff+0xd0/0xf8
   ksys_mmap_pgoff+0x88/0xf8
   __arm64_sys_mmap+0x28/0x38
   el0_svc_handler+0xd8/0x138
   el0_svc+0x8/0xc

Fixes: 855ab61c16bf70b646 ("coresight: tmc-etr: Refactor function tmc_etr_setup_perf_buf()")
Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
---
 drivers/hwtracing/coresight/coresight-tmc-etr.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

Comments

Robin Murphy May 10, 2019, 10:38 a.m. UTC | #1
Hi Suzuki,

On 10/05/2019 10:31, Suzuki K Poulose wrote:
> Instead of using smp_processor_id() to figure out the node,
> use the numa_node_id() for the current CPU node to avoid
> splats like :
> 
>   BUG: using smp_processor_id() in preemptible [00000000] code: perf/1743
>   caller is alloc_etr_buf.isra.6+0x80/0xa0
>   CPU: 1 PID: 1743 Comm: perf Not tainted 5.1.0-rc6-147786-g116841e #344
>   Hardware name: ARM LTD ARM Juno Development Platform/ARM Juno Development Platform, BIOS EDK II Feb  1 2019
>    Call trace:
>     dump_backtrace+0x0/0x150
>     show_stack+0x14/0x20
>     dump_stack+0x9c/0xc4
>     debug_smp_processor_id+0x10c/0x110
>     alloc_etr_buf.isra.6+0x80/0xa0
>     tmc_alloc_etr_buffer+0x12c/0x1f0
>     etm_setup_aux+0x1c4/0x230
>     rb_alloc_aux+0x1b8/0x2b8
>     perf_mmap+0x35c/0x478
>     mmap_region+0x34c/0x4f0
>     do_mmap+0x2d8/0x418
>     vm_mmap_pgoff+0xd0/0xf8
>     ksys_mmap_pgoff+0x88/0xf8
>     __arm64_sys_mmap+0x28/0x38
>     el0_svc_handler+0xd8/0x138
>     el0_svc+0x8/0xc
> 
> Fixes: 855ab61c16bf70b646 ("coresight: tmc-etr: Refactor function tmc_etr_setup_perf_buf()")
> Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
> Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
> ---
>   drivers/hwtracing/coresight/coresight-tmc-etr.c | 6 ++----
>   1 file changed, 2 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/hwtracing/coresight/coresight-tmc-etr.c b/drivers/hwtracing/coresight/coresight-tmc-etr.c
> index 793639f..cae9d8a 100644
> --- a/drivers/hwtracing/coresight/coresight-tmc-etr.c
> +++ b/drivers/hwtracing/coresight/coresight-tmc-etr.c
> @@ -1323,13 +1323,11 @@ static struct etr_perf_buffer *
>   tmc_etr_setup_perf_buf(struct tmc_drvdata *drvdata, struct perf_event *event,
>   		       int nr_pages, void **pages, bool snapshot)
>   {
> -	int node, cpu = event->cpu;
> +	int node;
>   	struct etr_buf *etr_buf;
>   	struct etr_perf_buffer *etr_perf;
>   
> -	if (cpu == -1)
> -		cpu = smp_processor_id();
> -	node = cpu_to_node(cpu);
> +	node = (event->cpu == -1) ? numa_node_id() : cpu_to_node(event->cpu);

If cpu == -1 represents a "don't care" scenario, it might be clearer to 
just use NUMA_NO_NODE instead, and let the allocator handle it.

Robin.

>   
>   	etr_perf = kzalloc_node(sizeof(*etr_perf), GFP_KERNEL, node);
>   	if (!etr_perf)
>
Suzuki K Poulose May 30, 2019, 3:52 p.m. UTC | #2
Hi Robin,

On 10/05/2019 11:38, Robin Murphy wrote:
> Hi Suzuki,
> 
> On 10/05/2019 10:31, Suzuki K Poulose wrote:
>> Instead of using smp_processor_id() to figure out the node,
>> use the numa_node_id() for the current CPU node to avoid
>> splats like :


>
>> diff --git a/drivers/hwtracing/coresight/coresight-tmc-etr.c b/drivers/hwtracing/coresight/coresight-tmc-etr.c
>> index 793639f..cae9d8a 100644
>> --- a/drivers/hwtracing/coresight/coresight-tmc-etr.c
>> +++ b/drivers/hwtracing/coresight/coresight-tmc-etr.c
>> @@ -1323,13 +1323,11 @@ static struct etr_perf_buffer *
>>    tmc_etr_setup_perf_buf(struct tmc_drvdata *drvdata, struct perf_event *event,
>>    		       int nr_pages, void **pages, bool snapshot)
>>    {
>> -	int node, cpu = event->cpu;
>> +	int node;
>>    	struct etr_buf *etr_buf;
>>    	struct etr_perf_buffer *etr_perf;
>>    
>> -	if (cpu == -1)
>> -		cpu = smp_processor_id();
>> -	node = cpu_to_node(cpu);
>> +	node = (event->cpu == -1) ? numa_node_id() : cpu_to_node(event->cpu);
> 
> If cpu == -1 represents a "don't care" scenario, it might be clearer to
> just use NUMA_NO_NODE instead, and let the allocator handle it.

Thanks for the suggestion, will use that instead

Cheers
Suzuki

Patch
diff mbox series

diff --git a/drivers/hwtracing/coresight/coresight-tmc-etr.c b/drivers/hwtracing/coresight/coresight-tmc-etr.c
index 793639f..cae9d8a 100644
--- a/drivers/hwtracing/coresight/coresight-tmc-etr.c
+++ b/drivers/hwtracing/coresight/coresight-tmc-etr.c
@@ -1323,13 +1323,11 @@  static struct etr_perf_buffer *
 tmc_etr_setup_perf_buf(struct tmc_drvdata *drvdata, struct perf_event *event,
 		       int nr_pages, void **pages, bool snapshot)
 {
-	int node, cpu = event->cpu;
+	int node;
 	struct etr_buf *etr_buf;
 	struct etr_perf_buffer *etr_perf;
 
-	if (cpu == -1)
-		cpu = smp_processor_id();
-	node = cpu_to_node(cpu);
+	node = (event->cpu == -1) ? numa_node_id() : cpu_to_node(event->cpu);
 
 	etr_perf = kzalloc_node(sizeof(*etr_perf), GFP_KERNEL, node);
 	if (!etr_perf)