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Subject[PATCH 3/5] perf_counter: rework ioctl()s
Corey noticed that ioctl()s on grouped counters didn't work on the whole group.
This extends the ioctl() interface to take a second argument that is
interpreted as a flags field. We then provide PERF_IOC_FLAG_GROUP to toggle
the behaviour.

Having this flag gives the greatest flexibility, allowing you to individually
enable/disable/reset counters in a group, or all together.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
---
include/linux/perf_counter.h | 10 ++--
kernel/perf_counter.c | 104 +++++++++++++++++++++++--------------------
2 files changed, 65 insertions(+), 49 deletions(-)
Index: linux-2.6/kernel/perf_counter.c
===================================================================
--- linux-2.6.orig/kernel/perf_counter.c
+++ linux-2.6/kernel/perf_counter.c
@@ -82,7 +82,7 @@ list_add_counter(struct perf_counter *co
* add it straight to the context's counter list, or to the group
* leader's sibling list:
*/
- if (counter->group_leader == counter)
+ if (group_leader == counter)
list_add_tail(&counter->list_entry, &ctx->counter_list);
else {
list_add_tail(&counter->list_entry, &group_leader->sibling_list);
@@ -385,24 +385,6 @@ static void perf_counter_disable(struct
spin_unlock_irq(&ctx->lock);
}

-/*
- * Disable a counter and all its children.
- */
-static void perf_counter_disable_family(struct perf_counter *counter)
-{
- struct perf_counter *child;
-
- perf_counter_disable(counter);
-
- /*
- * Lock the mutex to protect the list of children
- */
- mutex_lock(&counter->mutex);
- list_for_each_entry(child, &counter->child_list, child_list)
- perf_counter_disable(child);
- mutex_unlock(&counter->mutex);
-}
-
static int
counter_sched_in(struct perf_counter *counter,
struct perf_cpu_context *cpuctx,
@@ -753,24 +735,6 @@ static int perf_counter_refresh(struct p
return 0;
}

-/*
- * Enable a counter and all its children.
- */
-static void perf_counter_enable_family(struct perf_counter *counter)
-{
- struct perf_counter *child;
-
- perf_counter_enable(counter);
-
- /*
- * Lock the mutex to protect the list of children
- */
- mutex_lock(&counter->mutex);
- list_for_each_entry(child, &counter->child_list, child_list)
- perf_counter_enable(child);
- mutex_unlock(&counter->mutex);
-}
-
void __perf_counter_sched_out(struct perf_counter_context *ctx,
struct perf_cpu_context *cpuctx)
{
@@ -1307,31 +1271,79 @@ static unsigned int perf_poll(struct fil

static void perf_counter_reset(struct perf_counter *counter)
{
+ (void)perf_counter_read(counter);
atomic_set(&counter->count, 0);
+ perf_counter_update_userpage(counter);
+}
+
+static void perf_counter_for_each_sibling(struct perf_counter *counter,
+ void (*func)(struct perf_counter *))
+{
+ struct perf_counter_context *ctx = counter->ctx;
+ struct perf_counter *sibling;
+
+ spin_lock_irq(&ctx->lock);
+ counter = counter->group_leader;
+
+ func(counter);
+ list_for_each_entry(sibling, &counter->sibling_list, list_entry)
+ func(sibling);
+ spin_unlock_irq(&ctx->lock);
+}
+
+static void perf_counter_for_each_child(struct perf_counter *counter,
+ void (*func)(struct perf_counter *))
+{
+ struct perf_counter *child;
+
+ mutex_lock(&counter->mutex);
+ func(counter);
+ list_for_each_entry(child, &counter->child_list, child_list)
+ func(child);
+ mutex_unlock(&counter->mutex);
+}
+
+static void perf_counter_for_each(struct perf_counter *counter,
+ void (*func)(struct perf_counter *))
+{
+ struct perf_counter *child;
+
+ mutex_lock(&counter->mutex);
+ perf_counter_for_each_sibling(counter, func);
+ list_for_each_entry(child, &counter->child_list, child_list)
+ perf_counter_for_each_sibling(child, func);
+ mutex_unlock(&counter->mutex);
}

static long perf_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
struct perf_counter *counter = file->private_data;
- int err = 0;
+ void (*func)(struct perf_counter *);
+ u32 flags = arg;

switch (cmd) {
case PERF_COUNTER_IOC_ENABLE:
- perf_counter_enable_family(counter);
+ func = perf_counter_enable;
break;
case PERF_COUNTER_IOC_DISABLE:
- perf_counter_disable_family(counter);
- break;
- case PERF_COUNTER_IOC_REFRESH:
- err = perf_counter_refresh(counter, arg);
+ func = perf_counter_disable;
break;
case PERF_COUNTER_IOC_RESET:
- perf_counter_reset(counter);
+ func = perf_counter_reset;
break;
+
+ case PERF_COUNTER_IOC_REFRESH:
+ return perf_counter_refresh(counter, arg);
default:
- err = -ENOTTY;
+ return -ENOTTY;
}
- return err;
+
+ if (flags & PERF_IOC_FLAG_GROUP)
+ perf_counter_for_each(counter, func);
+ else
+ perf_counter_for_each_child(counter, func);
+
+ return 0;
}

/*
Index: linux-2.6/include/linux/perf_counter.h
===================================================================
--- linux-2.6.orig/include/linux/perf_counter.h
+++ linux-2.6/include/linux/perf_counter.h
@@ -157,10 +157,14 @@ struct perf_counter_hw_event {
/*
* Ioctls that can be done on a perf counter fd:
*/
-#define PERF_COUNTER_IOC_ENABLE _IO ('$', 0)
-#define PERF_COUNTER_IOC_DISABLE _IO ('$', 1)
+#define PERF_COUNTER_IOC_ENABLE _IOW('$', 0, u32)
+#define PERF_COUNTER_IOC_DISABLE _IOW('$', 1, u32)
#define PERF_COUNTER_IOC_REFRESH _IOW('$', 2, u32)
-#define PERF_COUNTER_IOC_RESET _IO ('$', 3)
+#define PERF_COUNTER_IOC_RESET _IOW('$', 3, u32)
+
+enum perf_counter_ioc_flags {
+ PERF_IOC_FLAG_GROUP = 1U << 0,
+};

/*
* Structure of the page that can be mapped via mmap
--



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