Commit-ID: c464c76eec4be587604ca082e8cded7e6b89f3bf
Gitweb: http://git.kernel.org/tip/c464c76eec4be587604ca082e8cded7e6b89f3bf
Author: Yan, Zheng <zheng.z.yan@xxxxxxxxx>
AuthorDate: Tue, 18 Mar 2014 16:56:41 +0800
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Fri, 18 Apr 2014 12:54:45 +0200
perf: Allow building PMU drivers as modules
This patch adds support for building PMU driver as module. It exports
the functions perf_pmu_{register,unregister}() and adds reference tracking
for the PMU driver module.
When the PMU driver is built as a module, each active event of the PMU
holds a reference to the driver module.
Signed-off-by: Yan, Zheng <zheng.z.yan@xxxxxxxxx>
Signed-off-by: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Link: http://lkml.kernel.org/r/1395133004-23205-1-git-send-email-zheng.z.yan@xxxxxxxxx
Cc: eranian@xxxxxxxxxx
Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: linux-kernel@xxxxxxxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
include/linux/perf_event.h | 1 +
kernel/events/core.c | 15 +++++++++++++++
2 files changed, 16 insertions(+)
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 3356abc..af6dcf1 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -172,6 +172,7 @@ struct perf_event;
struct pmu {
struct list_head entry;
+ struct module *module;
struct device *dev;
const struct attribute_group **attr_groups;
const char *name;
diff --git a/kernel/events/core.c b/kernel/events/core.c
index f83a71a..5129b12 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -39,6 +39,7 @@
#include <linux/hw_breakpoint.h>
#include <linux/mm_types.h>
#include <linux/cgroup.h>
+#include <linux/module.h>
#include "internal.h"
@@ -3229,6 +3230,9 @@ static void __free_event(struct perf_event *event)
if (event->ctx)
put_ctx(event->ctx);
+ if (event->pmu)
+ module_put(event->pmu->module);
+
call_rcu(&event->rcu_head, free_event_rcu);
}
static void free_event(struct perf_event *event)
@@ -6551,6 +6555,7 @@ free_pdc:
free_percpu(pmu->pmu_disable_count);
goto unlock;
}
+EXPORT_SYMBOL_GPL(perf_pmu_register);
void perf_pmu_unregister(struct pmu *pmu)
{
@@ -6572,6 +6577,7 @@ void perf_pmu_unregister(struct pmu *pmu)
put_device(pmu->dev);
free_pmu_context(pmu);
}
+EXPORT_SYMBOL_GPL(perf_pmu_unregister);
struct pmu *perf_init_event(struct perf_event *event)
{
@@ -6585,6 +6591,10 @@ struct pmu *perf_init_event(struct perf_event *event)
pmu = idr_find(&pmu_idr, event->attr.type);
rcu_read_unlock();
if (pmu) {
+ if (!try_module_get(pmu->module)) {
+ pmu = ERR_PTR(-ENODEV);
+ goto unlock;
+ }
event->pmu = pmu;
ret = pmu->event_init(event);
if (ret)
@@ -6593,6 +6603,10 @@ struct pmu *perf_init_event(struct perf_event *event)
}
list_for_each_entry_rcu(pmu, &pmus, entry) {
+ if (!try_module_get(pmu->module)) {
+ pmu = ERR_PTR(-ENODEV);
+ goto unlock;
+ }
event->pmu = pmu;
ret = pmu->event_init(event);
if (!ret)
@@ -6771,6 +6785,7 @@ perf_event_alloc(struct perf_event_attr *attr, int cpu,
err_pmu:
if (event->destroy)
event->destroy(event);
+ module_put(pmu->module);
err_ns:
if (event->ns)
put_pid_ns(event->ns);
--
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