On Tue, 11 Jun 2013 18:42:39 +0200, Robert Richter wrote:
> From: Robert Richter <robert.rich...@linaro.org>
>
> Expose persistent events in the system to userland using sysfs. Perf
> tools are able to read existing pmu events from sysfs. Now we use a
> persistent pmu as an event container containing all registered
> persistent events of the system. This patch adds dynamically
> registration of persistent events to sysfs. E.g. something like this:
>
>
> /sys/bus/event_source/devices/persistent/events/mce_record:persistent,config=106
> /sys/bus/event_source/devices/persistent/format/persistent:attr5:23
>
> Perf tools need to support the attr<num> syntax that is added in a
> separate patch set. With it we are able to run perf tool commands to
> read persistent events, e.g.:
>
> # perf record -e persistent/mce_record/ sleep 10
> # perf top -e persistent/mce_record/
>
> [ Document attr<index> syntax in sysfs ABI ]
> Reported-by: Jiri Olsa <jo...@redhat.com>
> Signed-off-by: Robert Richter <robert.rich...@linaro.org>
> Signed-off-by: Robert Richter <r...@kernel.org>
> ---
[SNIP]
> +static int pers_event_sysfs_register(struct pers_event *event)
> +{
> + struct device_attribute *attr = &event->sysfs.attr;
> + int idx;
> +
> + *attr = (struct device_attribute)__ATTR(, 0444, pers_event_sysfs_show,
> + NULL);
> + attr->attr.name = event->name;
When I added another persistent event with this API, I got an WARNING
from lockdep like this:
[ 0.432506] BUG: key ffff88040946f140 not in .data!
[ 0.432581] ------------[ cut here ]------------
[ 0.432656] WARNING: at /home/namhyung/project/linux/kernel/lockdep.c:2987
lockdep_init_map+0x53d/0x570()
[ 0.432763] DEBUG_LOCKS_WARN_ON(1)
I guess we need the following line here:
sysfs_attr_init(&attr->attr);
Thanks,
Namhyung
> +
> + /* add sysfs attr to events: */
> + for (idx = 0; idx < MAX_EVENTS; idx++) {
> + if (!cmpxchg(persistent_events_attr + idx, NULL, &attr->attr))
> + break;
> + }
> +
> + if (idx >= MAX_EVENTS)
> + return -ENOSPC;
> + if (!idx)
> + EVENTS_GROUP = &persistent_events_group;
> + if (!persistent_pmu.dev)
> + return 0; /* sysfs not yet initialized */
> + if (idx)
> + return sysfs_update_group(&persistent_pmu.dev->kobj,
> + EVENTS_GROUP);
> + return sysfs_create_group(&persistent_pmu.dev->kobj, EVENTS_GROUP);
> +}
>
> static int persistent_pmu_init(struct perf_event *event)
> {
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