Re: [PATCH v3 1/4] coresight: tmc-etr: Do not call smp_processor_id() from preemptible

From: Mathieu Poirier <mathieu.poirier@linaro.org>
To: Suzuki K Poulose <suzuki.poulose@arm.com>
Cc: coresight@lists.linaro.org, robin.murphy@arm.com,
	linux-kernel@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v3 1/4] coresight: tmc-etr: Do not call smp_processor_id() from preemptible
Date: Mon, 3 Jun 2019 13:29:02 -0600	[thread overview]
Message-ID: <20190603192902.GB20462@xps15> (raw)
In-Reply-To: <1559235267-25232-2-git-send-email-suzuki.poulose@arm.com>

On Thu, May 30, 2019 at 05:54:24PM +0100, 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 :

I was in the process of applying this set when I noticed the changelogs are
still referring to numa_node_id(), which is not part of the solution anymore.
Please address in all 4 patches.

Mathieu

> 
>  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 ce0114a..7c81f63 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_NO_NODE : cpu_to_node(event->cpu);
>  
>  	etr_perf = kzalloc_node(sizeof(*etr_perf), GFP_KERNEL, node);
>  	if (!etr_perf)
> -- 
> 2.7.4
> 

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