On Thu, 5 Jul 2018 16:13:42 -0600
Mathieu Poirier <mathieu.poirier@xxxxxxxxxx> wrote:
Hi Mathieu,
> This patch adds the mechanic needed for user space to send PMU specific
^^^^^^^^
I think you meant 'mechanism' here: mechanics fix cars :)
> +static void perf_drv_config_replace(struct perf_event *event, void *drv_data)
> +{
> + unsigned long flags;
> + void *old_drv_data;
> + struct pmu_drv_config *drv_config = &event->hw.drv_config;
> +
> + if (!has_drv_config(event))
> + return;
> +
> + /* Children take their configuration from their parent */
> + if (event->parent)
> + return;
> +
> + /* Make sure the PMU doesn't get a handle on the data */
> + raw_spin_lock_irqsave(&drv_config->lock, flags);
> +
> + old_drv_data = drv_config->config;
> + drv_config->config = drv_data;
> +
> + raw_spin_unlock_irqrestore(&drv_config->lock, flags);
> +
> + /* Free PMU private data allocated by pmu::drv_config_validate() */
> + event->pmu->drv_config_free(old_drv_data);
> +}
I got this stacktrace whilst testing a perf tool *without* this series
applied, running on a kernel *with* this series applied:
[ 132.942054] INFO: trying to register non-static key.
[ 132.946964] the code is fine but needs lockdep annotation.
[ 132.952389] turning off the locking correctness validator.
[ 132.957818] CPU: 2 PID: 2835 Comm: perf64-sans Not tainted 4.18.0-rc3-00196-g5b5d957532a8-dirty #146
[ 132.966856] Hardware name: ARM LTD ARM Juno Development Platform/ARM Juno Development Platform, BIOS EDK II Jan 23 2017
[ 132.977527] Call trace:
[ 132.979947] dump_backtrace+0x0/0x1c0
[ 132.983567] show_stack+0x24/0x30
[ 132.986845] dump_stack+0x90/0xb4
[ 132.990122] register_lock_class+0x57c/0x580
[ 132.994343] __lock_acquire.isra.12+0x6c/0x980
[ 132.998736] lock_acquire+0x100/0x1e8
[ 133.002357] _raw_spin_lock_irqsave+0x58/0x78
[ 133.006667] perf_drv_config_replace+0x4c/0x80
[ 133.011061] _free_event+0xbc/0x460
[ 133.014507] put_event+0x2c/0x38
[ 133.017697] perf_event_release_kernel+0x1ac/0x300
[ 133.022434] perf_release+0x10/0x20
[ 133.025883] __fput+0xa8/0x1e0
[ 133.028901] ____fput+0x20/0x30
[ 133.032006] task_work_run+0xa0/0xd0
[ 133.035539] do_notify_resume+0x118/0x120
[ 133.039503] work_pending+0x8/0x10
Is a raw_spin_lock_init missing perhaps?
Thanks,
Kim
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