From: Robin Murphy <robin.murphy@arm.com>
To: Suzuki K Poulose <suzuki.poulose@arm.com>, mathieu.poirier@linaro.org
Cc: coresight@lists.linaro.org, linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 1/4] coresight: tmc-etr: Do not call smp_processor_id() from preemptible
Date: Fri, 10 May 2019 11:38:28 +0100 [thread overview]
Message-ID: <319d4d63-326b-9bb5-6a24-f7aa8ec549f9@arm.com> (raw)
In-Reply-To: <1557480663-16759-2-git-send-email-suzuki.poulose@arm.com>
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)
>
next prev parent reply other threads:[~2019-05-10 10:38 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-05-10 9:30 [PATCH 0/4] coresight: Do not call smp_processor_id from preemptible contexts Suzuki K Poulose
2019-05-10 9:31 ` [PATCH 1/4] coresight: tmc-etr: Do not call smp_processor_id() from preemptible Suzuki K Poulose
2019-05-10 10:38 ` Robin Murphy [this message]
2019-05-30 15:52 ` Suzuki K Poulose
2019-05-10 9:31 ` [PATCH 2/4] coresight: tmc-etr: alloc_perf_buf: Do not call smp_processor_id " Suzuki K Poulose
2019-05-10 9:31 ` [PATCH 3/4] coresight: tmc-etf: " Suzuki K Poulose
2019-05-10 9:31 ` [PATCH 4/4] coresight: etb10: " Suzuki K Poulose
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