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@chris-wilson.co.uk Cc: Sumit Semwal sumit.semwal@linaro.org Cc: Shuah Khan shuahkh@osg.samsung.com Cc: Tejun Heo tj@kernel.org Cc: Daniel Vetter daniel.vetter@ffwll.ch Cc: Andrew Morton akpm@linux-foundation.org Cc: Ingo Molnar mingo@kernel.org Cc: Kees Cook keescook@chromium.org Cc: Thomas Gleixner tglx@linutronix.de Cc: "Paul E. McKenney" paulmck@linux.vnet.ibm.com Cc: Dan Williams dan.j.williams@intel.com Cc: Andrey Ryabinin aryabinin@virtuozzo.com Cc: Davidlohr Bueso dave@stgolabs.net Cc: Nikolay Aleksandrov nikolay@cumulusnetworks.com Cc: "David S. Miller" davem@davemloft.net Cc: "Peter Zijlstra (Intel)" peterz@infradead.org Cc: Rasmus Villemoes linux@rasmusvillemoes.dk Cc: Andy Shevchenko andriy.shevchenko@linux.intel.com Cc: Dmitry Vyukov dvyukov@google.com Cc: Alexander Potapenko glider@google.com Cc: linux-kernel@vger.kernel.org Cc: linux-media@vger.kernel.org Cc: dri-devel@lists.freedesktop.org Cc: linaro-mm-sig@lists.linaro.org --- 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; }