dma-buf provides an interfaces for receiving notifications from DMA hardware. kfence provides a useful interface for collecting such fences and combining them with other events.

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 | 4 ++++ kernel/async.c | 63 ++++++++++++++++++++++++++++++++++++++++++++++++-- 2 files changed, 65 insertions(+), 2 deletions(-)

diff --git a/include/linux/kfence.h b/include/linux/kfence.h index 82096bfafaa1..d71f30c626ae 100644 --- a/include/linux/kfence.h +++ b/include/linux/kfence.h @@ -15,6 +15,7 @@ #include <linux/wait.h>

struct completion; +struct fence;

struct kfence { wait_queue_head_t wait; @@ -29,6 +30,9 @@ extern int kfence_add(struct kfence *fence, struct kfence *after, gfp_t gfp); extern int kfence_add_completion(struct kfence *fence, struct completion *x, gfp_t gfp); +extern int kfence_add_dma(struct kfence *fence, + struct fence *dma, + 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 db22b890711e..01552d23a916 100644 --- a/kernel/async.c +++ b/kernel/async.c @@ -50,6 +50,7 @@ asynchronous and synchronous parts of the kernel.

#include <linux/async.h> #include <linux/atomic.h> +#include <linux/fence.h> #include <linux/kfence.h> #include <linux/ktime.h> #include <linux/export.h> @@ -122,9 +123,10 @@ static atomic_t entry_count; * allowing multiple pending / signals to be sent before the kfence is * complete. * - * kfence_add() / kfence_add_completion() + * kfence_add() / kfence_add_completion() / kfence_add_dma() * - * sets the kfence to wait upon another fence, or completion respectively. + * sets the kfence to wait upon another fence, completion, or DMA fence + * respectively. * * Unlike completions, kfences are expected to live inside more complex graphs * and form the basis for parallel execution of interdependent and so are @@ -484,6 +486,63 @@ int kfence_add_completion(struct kfence *fence, struct completion *x, gfp_t gfp) } EXPORT_SYMBOL_GPL(kfence_add_completion);

+struct dma_fence_cb { + struct fence_cb base; + struct kfence *fence; +}; + +static void dma_kfence_wake(struct fence *dma, struct fence_cb *data) +{ + struct dma_fence_cb *cb = container_of(data, typeof(*cb), base); + kfence_signal(cb->fence); + kfence_put(cb->fence); + kfree(cb); +} + +/** + * kfence_add_dma - set the fence to wait upon a DMA fence + * @fence: this kfence + * @dma: target DMA fence to wait upon + * @gfp: the allowed allocation type + * + * kfence_add_dma() causes the @fence to wait upon completion of a DMA fence. + * + * Returns 1 if the @fence was successfully to the waitqueue of @dma, 0 + * if @dma was already signaled (and so not added), or a negative error code. + */ +int kfence_add_dma(struct kfence *fence, struct fence *dma, gfp_t gfp) +{ + struct dma_fence_cb *cb; + int ret; + + if (!dma || fence_is_signaled(dma)) + return 0; + + cb = kmalloc(sizeof(*cb), gfp); + if (!cb) { + if (!gfpflags_allow_blocking(gfp)) + return -ENOMEM; + + return fence_wait(dma, false); + } + + cb->fence = kfence_get(fence); + kfence_pending(fence); + + ret = fence_add_callback(dma, &cb->base, dma_kfence_wake); + if (ret == 0) { + /* signal fence add and is pending */ + ret = 1; + } else { + dma_kfence_wake(dma, &cb->base); + if (ret == -ENOENT) /* fence already signaled */ + ret = 0; + } + + return ret; +} +EXPORT_SYMBOL_GPL(kfence_add_dma); + static async_cookie_t lowest_in_progress(struct async_domain *domain) { struct list_head *pending;