On Wed, Jun 11, 2014 at 06:41:48PM +0300, Alexander Shishkin wrote:
> +static bool exclusive_event_ok(struct perf_event *event,
> + struct perf_event_context *ctx)
> +{
> + struct perf_event *iter_event;
> +
> + if (!(event->pmu->capabilities & PERF_PMU_CAP_EXCLUSIVE))
> + return true;
> +
> + list_for_each_entry(iter_event, &ctx->event_list, event_entry) {
> + if (exclusive_event_match(iter_event, event))
> + return false;
> + }
This list iteration needs either rcu or ctx->lock or ctx->mutex, and the
two callsites below don't have either afaict.
> +
> + return true;
> +}
> +
> /**
> * sys_perf_event_open - open a performance event, associate it to a task/cpu
> *
> @@ -7261,6 +7287,11 @@ SYSCALL_DEFINE5(perf_event_open,
> goto err_alloc;
> }
>
> + if (!exclusive_event_ok(event, ctx)) {
> + err = -EBUSY;
> + goto err_context;
> + }
> +
> if (task) {
> put_task_struct(task);
> task = NULL;
> @@ -7427,6 +7458,13 @@ perf_event_create_kernel_counter(struct
> perf_event_attr *attr, int cpu,
> goto err_free;
> }
>
> + if (!exclusive_event_ok(event, ctx)) {
> + perf_unpin_context(ctx);
> + put_ctx(ctx);
> + err = -EBUSY;
> + goto err_free;
> + }
> +
> WARN_ON_ONCE(ctx->parent_ctx);
> mutex_lock(&ctx->mutex);
> perf_install_in_context(ctx, event, cpu);
> --
> 2.0.0
>
pgpTEFSX3FEZZ.pgp
Description: PGP signature
