[tip:perfcounters/core] perf_counter: Change pctrl() behaviour

From: tip-bot for Peter Zijlstra
Date: Sun May 24 2009 - 03:03:31 EST

Commit-ID: 082ff5a2767a0679ee543f14883adbafb631ffbe
Gitweb: http://git.kernel.org/tip/082ff5a2767a0679ee543f14883adbafb631ffbe
Author: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
AuthorDate: Sat, 23 May 2009 18:29:00 +0200
Committer: Ingo Molnar <mingo@xxxxxxx>
CommitDate: Sun, 24 May 2009 08:24:08 +0200

perf_counter: Change pctrl() behaviour

Instead of en/dis-abling all counters acting on a particular
task, en/dis- able all counters we created.

[ v2: fix crash on first counter enable ]

Signed-off-by: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Cc: Paul Mackerras <paulus@xxxxxxxxx>
Cc: Corey Ashford <cjashfor@xxxxxxxxxxxxxxxxxx>
Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Cc: John Kacur <jkacur@xxxxxxxxxx>
LKML-Reference: <20090523163012.916937244@xxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxx>


---
include/linux/init_task.h | 10 +++++
include/linux/perf_counter.h | 3 +
include/linux/sched.h | 2 +
kernel/perf_counter.c | 87 +++++++++++------------------------------
4 files changed, 39 insertions(+), 63 deletions(-)

diff --git a/include/linux/init_task.h b/include/linux/init_task.h
index d87247d..353c0ac 100644
--- a/include/linux/init_task.h
+++ b/include/linux/init_task.h
@@ -108,6 +108,15 @@ extern struct group_info init_groups;

extern struct cred init_cred;

+#ifdef CONFIG_PERF_COUNTERS
+# define INIT_PERF_COUNTERS(tsk) \
+ .perf_counter_mutex = \
+ __MUTEX_INITIALIZER(tsk.perf_counter_mutex), \
+ .perf_counter_list = LIST_HEAD_INIT(tsk.perf_counter_list),
+#else
+# define INIT_PERF_COUNTERS(tsk)
+#endif
+
/*
* INIT_TASK is used to set up the first task table, touch at
* your own risk!. Base=0, limit=0x1fffff (=2MB)
@@ -171,6 +180,7 @@ extern struct cred init_cred;
}, \
.dirties = INIT_PROP_LOCAL_SINGLE(dirties), \
INIT_IDS \
+ INIT_PERF_COUNTERS(tsk) \
INIT_TRACE_IRQFLAGS \
INIT_LOCKDEP \
INIT_FTRACE_GRAPH \
diff --git a/include/linux/perf_counter.h b/include/linux/perf_counter.h
index 4ab8050..4159ee5 100644
--- a/include/linux/perf_counter.h
+++ b/include/linux/perf_counter.h
@@ -469,6 +469,9 @@ struct perf_counter {
int oncpu;
int cpu;

+ struct list_head owner_entry;
+ struct task_struct *owner;
+
/* mmap bits */
struct mutex mmap_mutex;
atomic_t mmap_count;
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 9714d45..bc9326d 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1389,6 +1389,8 @@ struct task_struct {
#endif
#ifdef CONFIG_PERF_COUNTERS
struct perf_counter_context *perf_counter_ctxp;
+ struct mutex perf_counter_mutex;
+ struct list_head perf_counter_list;
#endif
#ifdef CONFIG_NUMA
struct mempolicy *mempolicy;
diff --git a/kernel/perf_counter.c b/kernel/perf_counter.c
index 0e97f89..4c86a63 100644
--- a/kernel/perf_counter.c
+++ b/kernel/perf_counter.c
@@ -1076,79 +1076,26 @@ static void perf_counter_cpu_sched_in(struct perf_cpu_context *cpuctx, int cpu)
__perf_counter_sched_in(ctx, cpuctx, cpu);
}

-int perf_counter_task_disable(void)
+int perf_counter_task_enable(void)
{
- struct task_struct *curr = current;
- struct perf_counter_context *ctx = curr->perf_counter_ctxp;
struct perf_counter *counter;
- unsigned long flags;
-
- if (!ctx || !ctx->nr_counters)
- return 0;
-
- local_irq_save(flags);

- __perf_counter_task_sched_out(ctx);
-
- spin_lock(&ctx->lock);
-
- /*
- * Disable all the counters:
- */
- perf_disable();
-
- list_for_each_entry(counter, &ctx->counter_list, list_entry) {
- if (counter->state != PERF_COUNTER_STATE_ERROR) {
- update_group_times(counter);
- counter->state = PERF_COUNTER_STATE_OFF;
- }
- }
-
- perf_enable();
-
- spin_unlock_irqrestore(&ctx->lock, flags);
+ mutex_lock(&current->perf_counter_mutex);
+ list_for_each_entry(counter, &current->perf_counter_list, owner_entry)
+ perf_counter_enable(counter);
+ mutex_unlock(&current->perf_counter_mutex);

return 0;
}

-int perf_counter_task_enable(void)
+int perf_counter_task_disable(void)
{
- struct task_struct *curr = current;
- struct perf_counter_context *ctx = curr->perf_counter_ctxp;
struct perf_counter *counter;
- unsigned long flags;
- int cpu;
-
- if (!ctx || !ctx->nr_counters)
- return 0;
-
- local_irq_save(flags);
- cpu = smp_processor_id();
-
- __perf_counter_task_sched_out(ctx);
-
- spin_lock(&ctx->lock);

- /*
- * Disable all the counters:
- */
- perf_disable();
-
- list_for_each_entry(counter, &ctx->counter_list, list_entry) {
- if (counter->state > PERF_COUNTER_STATE_OFF)
- continue;
- counter->state = PERF_COUNTER_STATE_INACTIVE;
- counter->tstamp_enabled =
- ctx->time - counter->total_time_enabled;
- counter->hw_event.disabled = 0;
- }
- perf_enable();
-
- spin_unlock(&ctx->lock);
-
- perf_counter_task_sched_in(curr, cpu);
-
- local_irq_restore(flags);
+ mutex_lock(&current->perf_counter_mutex);
+ list_for_each_entry(counter, &current->perf_counter_list, owner_entry)
+ perf_counter_disable(counter);
+ mutex_unlock(&current->perf_counter_mutex);

return 0;
}
@@ -1416,6 +1363,11 @@ static int perf_release(struct inode *inode, struct file *file)
perf_counter_remove_from_context(counter);
mutex_unlock(&ctx->mutex);

+ mutex_lock(&counter->owner->perf_counter_mutex);
+ list_del_init(&counter->owner_entry);
+ mutex_unlock(&counter->owner->perf_counter_mutex);
+ put_task_struct(counter->owner);
+
free_counter(counter);
put_context(ctx);

@@ -3272,6 +3224,12 @@ SYSCALL_DEFINE5(perf_counter_open,
perf_install_in_context(ctx, counter, cpu);
mutex_unlock(&ctx->mutex);

+ counter->owner = current;
+ get_task_struct(current);
+ mutex_lock(&current->perf_counter_mutex);
+ list_add_tail(&counter->owner_entry, &current->perf_counter_list);
+ mutex_unlock(&current->perf_counter_mutex);
+
fput_light(counter_file, fput_needed2);

out_fput:
@@ -3488,6 +3446,9 @@ void perf_counter_init_task(struct task_struct *child)

child->perf_counter_ctxp = NULL;

+ mutex_init(&child->perf_counter_mutex);
+ INIT_LIST_HEAD(&child->perf_counter_list);
+
/*
* This is executed from the parent task context, so inherit
* counters that have been marked for cloning.
--
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