kfence_add_delay() is a convenience wrapper around
hrtimer_start_range_ns() to provide a time source for a kfence graph.
Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Cc: Sumit Semwal <sumit.semwal@xxxxxxxxxx>
Cc: Shuah Khan <shuahkh@xxxxxxxxxxxxxxx>
Cc: Tejun Heo <tj@xxxxxxxxxx>
Cc: Daniel Vetter <daniel.vetter@xxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Kees Cook <keescook@xxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: "Paul E. McKenney" <paulmck@xxxxxxxxxxxxxxxxxx>
Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
Cc: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx>
Cc: Davidlohr Bueso <dave@xxxxxxxxxxxx>
Cc: Nikolay Aleksandrov <nikolay@xxxxxxxxxxxxxxxxxxx>
Cc: "David S. Miller" <davem@xxxxxxxxxxxxx>
Cc: "Peter Zijlstra (Intel)" <peterz@xxxxxxxxxxxxx>
Cc: Rasmus Villemoes <linux@xxxxxxxxxxxxxxxxxx>
Cc: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Cc: Alexander Potapenko <glider@xxxxxxxxxx>
Cc: linux-kernel@xxxxxxxxxxxxxxx
Cc: linux-media@xxxxxxxxxxxxxxx
Cc: dri-devel@xxxxxxxxxxxxxxxxxxxxx
Cc: linaro-mm-sig@xxxxxxxxxxxxxxxx
---
include/linux/kfence.h | 5 +++++
kernel/async.c | 60 +++++++++++++++++++++++++++++++++++++++++++++++++-
lib/test-kfence.c | 44 ++++++++++++++++++++++++++++++++++++
3 files changed, 108 insertions(+), 1 deletion(-)
diff --git a/include/linux/kfence.h b/include/linux/kfence.h
index d71f30c626ae..1abec5e6b23c 100644
--- a/include/linux/kfence.h
+++ b/include/linux/kfence.h
@@ -16,6 +16,7 @@
struct completion;
struct fence;
+enum hrtimer_mode;
struct kfence {
wait_queue_head_t wait;
@@ -33,6 +34,10 @@ extern int kfence_add_completion(struct kfence *fence,
extern int kfence_add_dma(struct kfence *fence,
struct fence *dma,
gfp_t gfp);
+extern int kfence_add_delay(struct kfence *fence,
+ clockid_t clock, enum hrtimer_mode mode,
+ ktime_t delay, u64 slack,
+ gfp_t gfp);
extern void kfence_pending(struct kfence *fence);
extern void kfence_signal(struct kfence *fence);
extern void kfence_wait(struct kfence *fence);
diff --git a/kernel/async.c b/kernel/async.c
index 01552d23a916..5d02445e36b7 100644
--- a/kernel/async.c
+++ b/kernel/async.c
@@ -126,7 +126,10 @@ static atomic_t entry_count;
* kfence_add() / kfence_add_completion() / kfence_add_dma()
*
* sets the kfence to wait upon another fence, completion, or DMA fence
- * respectively.
+ * respectively. To set the fence to wait for at least a certain period of
+ * time, or until after a certain point in time, use
+ *
+ * kfence_add_timer()
*
* Unlike completions, kfences are expected to live inside more complex graphs
* and form the basis for parallel execution of interdependent and so are
@@ -543,6 +546,61 @@ int kfence_add_dma(struct kfence *fence, struct fence *dma, gfp_t gfp)
}
EXPORT_SYMBOL_GPL(kfence_add_dma);
+/**
+ * kfence_add_delay - set the fence to wait for a period of time
+ * @fence: this kfence
+ * @clock: which clock to program
+ * @mode: delay given as relative or absolute
+ * @delay: how long or until what time to wait
+ * @slack: how much slack that may be applied to the delay
+ *
+ * kfence_add_delay() causes the @fence to wait for a a period of time, or
+ * until a certain point in time. It is a convenience wrapper around
+ * hrtimer_start_range_ns(). For more details on @clock, @mode, @delay and
+ * @slack please consult the hrtimer documentation.
+ *
+ * Returns 1 if the delay was sucessfuly added to the @fence, or a negative
+ * error code on failure.
+ */
+struct timer_cb {
+ struct hrtimer timer;
+ struct kfence *fence;
+};
+
+static enum hrtimer_restart
+timer_kfence_wake(struct hrtimer *timer)
+{
+ struct timer_cb *cb = container_of(timer, typeof(*cb), timer);
+
+ kfence_signal(cb->fence);
+ kfence_put(cb->fence);
+ kfree(cb);
+
+ return HRTIMER_NORESTART;
+}
+
+int kfence_add_delay(struct kfence *fence,
+ clockid_t clock, enum hrtimer_mode mode,
+ ktime_t delay, u64 slack,
+ gfp_t gfp)
+{
+ struct timer_cb *cb;
+
+ cb = kmalloc(sizeof(*cb), gfp);
+ if (!cb)
+ return -ENOMEM;
+
+ cb->fence = kfence_get(fence);
+ kfence_pending(fence);
+
+ hrtimer_init(&cb->timer, clock, mode);
+ cb->timer.function = timer_kfence_wake;
+
+ hrtimer_start_range_ns(&cb->timer, delay, slack, mode);
+ return 1;
+}
+EXPORT_SYMBOL_GPL(kfence_add_delay);
+
static async_cookie_t lowest_in_progress(struct async_domain *domain)
{
struct list_head *pending;
diff --git a/lib/test-kfence.c b/lib/test-kfence.c
index 0604a27f68b2..782a2cca19c5 100644
--- a/lib/test-kfence.c
+++ b/lib/test-kfence.c
@@ -341,6 +341,44 @@ static int __init test_completion(void)
return 0;
}
+static int __init test_delay(void)
+{
+ struct kfence *fence;
+ ktime_t delay;
+ int ret;
+
+ /* Test use of a hrtimer as an event source for kfences */
+ pr_debug("%s\n", __func__);
+
+ fence = kfence_create(GFP_KERNEL);
+ if (!fence)
+ return -ENOMEM;
+
+ delay = ktime_get();
+
+ ret = kfence_add_delay(fence, CLOCK_MONOTONIC, HRTIMER_MODE_REL,
+ ms_to_ktime(1), 1 << 10,
+ GFP_KERNEL);
+ if (ret < 0)
+ return ret;
+ if (ret == 0)
+ return -EINVAL;
+
+ kfence_signal(fence);
+ kfence_wait(fence);
+
+ delay = ktime_sub(ktime_get(), delay);
+ kfence_put(fence);
+
+ if (!ktime_to_ms(delay)) {
+ pr_err("kfence woke too early, delay was only %lldns\n",
+ (long long)ktime_to_ns(delay));
+ return -EINVAL;
+ }
+
+ return 0;
+}
+
struct task_ipc {
struct work_struct work;
struct completion started;
@@ -509,6 +547,12 @@ static int __init test_kfence_init(void)
return ret;
}
+ ret = test_delay();
+ if (ret < 0) {
+ pr_err("delay failed\n");
+ return ret;
+ }
+
return 0;
}
--
2.8.1
--
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