From mboxrd@z Thu Jan 1 00:00:00 1970 From: Maarten Lankhorst Subject: Re: [PATCH] dma-buf/sync_file: only enable fence signalling during wait Date: Tue, 12 Jul 2016 10:46:45 +0200 Message-ID: <58ef685f-0308-6828-6e21-ab5fd1302b84@linux.intel.com> References: <1467992691-12442-1-git-send-email-gustavo@padovan.org> <183b15e0-3072-6aa2-7d35-002c20752e0e@linux.intel.com> <20160711202713.GC2565@joana> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Return-path: Received: from mga14.intel.com (mga14.intel.com [192.55.52.115]) by gabe.freedesktop.org (Postfix) with ESMTP id D52E389AAD for ; Tue, 12 Jul 2016 08:46:50 +0000 (UTC) In-Reply-To: <20160711202713.GC2565@joana> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" To: Gustavo Padovan , dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, Daniel Stone , Daniel Vetter , Rob Clark , Greg Hackmann , John Harrison , laurent.pinchart@ideasonboard.com, seanpaul@google.com, marcheu@google.com, m.chehab@samsung.com, Sumit Semwal , Gustavo Padovan List-Id: dri-devel@lists.freedesktop.org T3AgMTEtMDctMTYgb20gMjI6Mjcgc2NocmVlZiBHdXN0YXZvIFBhZG92YW46Cj4gMjAxNi0wNy0x MCBNYWFydGVuIExhbmtob3JzdCA8bWFhcnRlbi5sYW5raG9yc3RAbGludXguaW50ZWwuY29tPjoK Pgo+PiBPcCAwOC0wNy0xNiBvbSAxNzo0NCBzY2hyZWVmIEd1c3Rhdm8gUGFkb3ZhbjoKPj4+IEZy b206IEd1c3Rhdm8gUGFkb3ZhbiA8Z3VzdGF2by5wYWRvdmFuQGNvbGxhYm9yYS5jby51az4KPj4+ Cj4+PiBTaWduYWxsaW5nIGRvZXNuJ3QgbmVlZCB0byBiZSBlbmFibGVkIGF0IHN5bmNfZmlsZSBj cmVhdGlvbiwgaXQgaXMgb25seQo+Pj4gcmVxdWlyZWQgaWYgdXNlcnNwYWNlIHdhaXRpbmcgdGhl IGZlbmNlIHRvIHNpZ25hbCB0aHJvdWdoIHBvbGwoKS4KPj4+Cj4+PiBUaHVzIHdlIGRlbGF5IGZl bmNlX2FkZF9jYWxsYmFjaygpIHVudGlsIHBvbGwgaXMgY2FsbGVkLiBJdCBvbmx5IGFkZHMgdGhl Cj4+PiBjYWxsYmFjayB0aGUgZmlyc3QgdGltZSBwb2xsKCkgaXMgY2FsbGVkLiBUaGlzIGF2b2lk IHJlLWFkZGluZyB0aGUgc2FtZQo+Pj4gY2FsbGJhY2sgbXVsdGlwbGUgdGltZXMuCj4+Pgo+Pj4g djI6IHJlYmFzZSBhbmQgdXBkYXRlIHRvIHdvcmsgd2l0aCBuZXcgZmVuY2Ugc3VwcG9ydCBmb3Ig c3luY19maWxlCj4+Pgo+Pj4gU2lnbmVkLW9mZi1ieTogR3VzdGF2byBQYWRvdmFuIDxndXN0YXZv LnBhZG92YW5AY29sbGFib3JhLmNvLnVrPgo+Pj4gLS0tCj4+PiBUaGlzIHBhdGNoIGFwcGxpZXMg b24gdG9wIG9mIG15IGxhdGVzdCBzeW5jX2ZpbGUgY2hhbmdlcyB0byBzdXBwb3J0Cj4+PiBmZW5j ZV9hcnJheTogaHR0cHM6Ly9sa21sLm9yZy9sa21sLzIwMTYvNy80LzUzNAo+Pj4KPj4+ICBkcml2 ZXJzL2RtYS1idWYvc3luY19maWxlLmMgfCAyMyArKysrKysrKysrKysrKy0tLS0tLS0tLQo+Pj4g IGluY2x1ZGUvbGludXgvc3luY19maWxlLmggICB8ICAyICsrCj4+PiAgMiBmaWxlcyBjaGFuZ2Vk LCAxNiBpbnNlcnRpb25zKCspLCA5IGRlbGV0aW9ucygtKQo+Pj4KPj4+IGRpZmYgLS1naXQgYS9k cml2ZXJzL2RtYS1idWYvc3luY19maWxlLmMgYi9kcml2ZXJzL2RtYS1idWYvc3luY19maWxlLmMK Pj4+IGluZGV4IDYxYTY4N2MuLjFkYjRhNjQgMTAwNjQ0Cj4+PiAtLS0gYS9kcml2ZXJzL2RtYS1i dWYvc3luY19maWxlLmMKPj4+ICsrKyBiL2RyaXZlcnMvZG1hLWJ1Zi9zeW5jX2ZpbGUuYwo+Pj4g QEAgLTg2LDggKzg2LDYgQEAgc3RydWN0IHN5bmNfZmlsZSAqc3luY19maWxlX2NyZWF0ZShzdHJ1 Y3QgZmVuY2UgKmZlbmNlKQo+Pj4gIAkJIGZlbmNlLT5vcHMtPmdldF90aW1lbGluZV9uYW1lKGZl bmNlKSwgZmVuY2UtPmNvbnRleHQsCj4+PiAgCQkgZmVuY2UtPnNlcW5vKTsKPj4+ICAKPj4+IC0J ZmVuY2VfYWRkX2NhbGxiYWNrKGZlbmNlLCAmc3luY19maWxlLT5jYiwgZmVuY2VfY2hlY2tfY2Jf ZnVuYyk7Cj4+PiAtCj4+PiAgCXJldHVybiBzeW5jX2ZpbGU7Cj4+PiAgfQo+Pj4gIEVYUE9SVF9T WU1CT0woc3luY19maWxlX2NyZWF0ZSk7Cj4+PiBAQCAtMjY5LDkgKzI2Nyw2IEBAIHN0YXRpYyBz dHJ1Y3Qgc3luY19maWxlICpzeW5jX2ZpbGVfbWVyZ2UoY29uc3QgY2hhciAqbmFtZSwgc3RydWN0 IHN5bmNfZmlsZSAqYSwKPj4+ICAJCWdvdG8gZXJyOwo+Pj4gIAl9Cj4+PiAgCj4+PiAtCWZlbmNl X2FkZF9jYWxsYmFjayhzeW5jX2ZpbGUtPmZlbmNlLCAmc3luY19maWxlLT5jYiwKPj4+IC0JCQkg ICBmZW5jZV9jaGVja19jYl9mdW5jKTsKPj4+IC0KPj4+ICAJc3RybGNweShzeW5jX2ZpbGUtPm5h bWUsIG5hbWUsIHNpemVvZihzeW5jX2ZpbGUtPm5hbWUpKTsKPj4+ICAJcmV0dXJuIHN5bmNfZmls ZTsKPj4+ICAKPj4+IEBAIC0yODYsNyArMjgxLDYgQEAgc3RhdGljIHZvaWQgc3luY19maWxlX2Zy ZWUoc3RydWN0IGtyZWYgKmtyZWYpCj4+PiAgCXN0cnVjdCBzeW5jX2ZpbGUgKnN5bmNfZmlsZSA9 IGNvbnRhaW5lcl9vZihrcmVmLCBzdHJ1Y3Qgc3luY19maWxlLAo+Pj4gIAkJCQkJCSAgICAga3Jl Zik7Cj4+PiAgCj4+PiAtCWZlbmNlX3JlbW92ZV9jYWxsYmFjayhzeW5jX2ZpbGUtPmZlbmNlLCAm c3luY19maWxlLT5jYik7Cj4+PiAgCWZlbmNlX3B1dChzeW5jX2ZpbGUtPmZlbmNlKTsKPj4+ICAJ a2ZyZWUoc3luY19maWxlKTsKPj4+ICB9Cj4+PiBAQCAtMzA2LDEzICszMDAsMjQgQEAgc3RhdGlj IHVuc2lnbmVkIGludCBzeW5jX2ZpbGVfcG9sbChzdHJ1Y3QgZmlsZSAqZmlsZSwgcG9sbF90YWJs ZSAqd2FpdCkKPj4+ICAKPj4+ICAJcG9sbF93YWl0KGZpbGUsICZzeW5jX2ZpbGUtPndxLCB3YWl0 KTsKPj4+ICAKPj4+ICsJaWYgKCFzeW5jX2ZpbGUtPmVuYWJsZWQpIHsKPj4+ICsJCWZlbmNlX2Fk ZF9jYWxsYmFjayhzeW5jX2ZpbGUtPmZlbmNlLCAmc3luY19maWxlLT5jYiwKPj4+ICsJCQkJICAg ZmVuY2VfY2hlY2tfY2JfZnVuYyk7Cj4+PiArCQlzeW5jX2ZpbGUtPmVuYWJsZWQgPSB0cnVlOwo+ Pj4gKwl9Cj4+IFdvbid0IHRoaXMgYmxvdyB1cCBjb21wbGV0ZWx5IHdpdGggMiB0aHJlYWRzIHBv bGxpbmcgYXQgdGhlIHNhbWUgdGltZT8KPiBJbmRlZWQsIHVzaW5nIGF0b21pYyBvcGVyYXRpb25z IG9uIGVuYWJsZWQgc2hvdWxkIGZpeCB0aGlzLgpObywgaXQgc3RpbGwgd291bGQgYmxvdyB1cCB3 aXRob3V0IGxvY2tpbmcgYXJvdW5kIGZlbmNlX3JlbW92ZS9hZGRfY2FsbGJhY2sgdG9vLi4KClBl cnNvbmFsbHkgSSB3b3VsZCBqdXN0IGFkZCB0aGUgY2FsbGJhY2sgb25jZSwgdGhlbiByZW1vdmUg aXQgaW4gZGVzdHJ1Y3Rvci4KClNvbWV0aGluZyBsaWtlOgoKcG9sbDoKaWYgKCFhdG9taWNfeGNo Zygmc3luY19maWxlLT5lbmFibGVkLCAxKSkgewppZiAoZmVuY2VfYWRkX2NhbGxiYWNrKC4uLikg PCAwKQp3YWtlIHVwIHN5bmNfZmlsZS0+d3EsIGZlbmNlIGlzIHNpZ25hbGVkCn0KCnN5bmNfZmls ZV9mcmVlOgppZiAoYXRvbWljX3JlYWQoJnN5bmNfZmlsZS0+ZW5hYmxlZCkpCmZlbmNlX3JlbW92 ZV9jYWxsYmFjayguLi4pOwoKZmVuY2VfcHV0KCkKCkl0J3Mgbm90IGxpa2UgZmVuY2UgY2FuIGRp c2FibGUgaHcgc2lnbmFsaW5nIHdoZW4gYWxsIGNhbGxiYWNrcyBhcmUgcmVtb3ZlZCBhbnl3YXks Cml0J3MgaGFybWxlc3MgdG8ga2VlcCBpdCBvbiB0aGUgbGlzdC4KCn5NYWFydGVuCl9fX19fX19f X19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fCmRyaS1kZXZlbCBtYWlsaW5n IGxpc3QKZHJpLWRldmVsQGxpc3RzLmZyZWVkZXNrdG9wLm9yZwpodHRwczovL2xpc3RzLmZyZWVk ZXNrdG9wLm9yZy9tYWlsbWFuL2xpc3RpbmZvL2RyaS1kZXZlbAo= From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752336AbcGLIqz (ORCPT ); Tue, 12 Jul 2016 04:46:55 -0400 Received: from mga04.intel.com ([192.55.52.120]:55550 "EHLO mga04.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751592AbcGLIqv (ORCPT ); Tue, 12 Jul 2016 04:46:51 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.28,351,1464678000"; d="scan'208";a="844699179" Subject: Re: [PATCH] dma-buf/sync_file: only enable fence signalling during wait To: Gustavo Padovan , dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, Daniel Stone , Daniel Vetter , Rob Clark , Greg Hackmann , John Harrison , laurent.pinchart@ideasonboard.com, seanpaul@google.com, marcheu@google.com, m.chehab@samsung.com, Sumit Semwal , Gustavo Padovan References: <1467992691-12442-1-git-send-email-gustavo@padovan.org> <183b15e0-3072-6aa2-7d35-002c20752e0e@linux.intel.com> <20160711202713.GC2565@joana> From: Maarten Lankhorst Message-ID: <58ef685f-0308-6828-6e21-ab5fd1302b84@linux.intel.com> Date: Tue, 12 Jul 2016 10:46:45 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.1.1 MIME-Version: 1.0 In-Reply-To: <20160711202713.GC2565@joana> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Op 11-07-16 om 22:27 schreef Gustavo Padovan: > 2016-07-10 Maarten Lankhorst : > >> Op 08-07-16 om 17:44 schreef Gustavo Padovan: >>> From: Gustavo Padovan >>> >>> Signalling doesn't need to be enabled at sync_file creation, it is only >>> required if userspace waiting the fence to signal through poll(). >>> >>> Thus we delay fence_add_callback() until poll is called. It only adds the >>> callback the first time poll() is called. This avoid re-adding the same >>> callback multiple times. >>> >>> v2: rebase and update to work with new fence support for sync_file >>> >>> Signed-off-by: Gustavo Padovan >>> --- >>> This patch applies on top of my latest sync_file changes to support >>> fence_array: https://lkml.org/lkml/2016/7/4/534 >>> >>> drivers/dma-buf/sync_file.c | 23 ++++++++++++++--------- >>> include/linux/sync_file.h | 2 ++ >>> 2 files changed, 16 insertions(+), 9 deletions(-) >>> >>> diff --git a/drivers/dma-buf/sync_file.c b/drivers/dma-buf/sync_file.c >>> index 61a687c..1db4a64 100644 >>> --- a/drivers/dma-buf/sync_file.c >>> +++ b/drivers/dma-buf/sync_file.c >>> @@ -86,8 +86,6 @@ struct sync_file *sync_file_create(struct fence *fence) >>> fence->ops->get_timeline_name(fence), fence->context, >>> fence->seqno); >>> >>> - fence_add_callback(fence, &sync_file->cb, fence_check_cb_func); >>> - >>> return sync_file; >>> } >>> EXPORT_SYMBOL(sync_file_create); >>> @@ -269,9 +267,6 @@ static struct sync_file *sync_file_merge(const char *name, struct sync_file *a, >>> goto err; >>> } >>> >>> - fence_add_callback(sync_file->fence, &sync_file->cb, >>> - fence_check_cb_func); >>> - >>> strlcpy(sync_file->name, name, sizeof(sync_file->name)); >>> return sync_file; >>> >>> @@ -286,7 +281,6 @@ static void sync_file_free(struct kref *kref) >>> struct sync_file *sync_file = container_of(kref, struct sync_file, >>> kref); >>> >>> - fence_remove_callback(sync_file->fence, &sync_file->cb); >>> fence_put(sync_file->fence); >>> kfree(sync_file); >>> } >>> @@ -306,13 +300,24 @@ static unsigned int sync_file_poll(struct file *file, poll_table *wait) >>> >>> poll_wait(file, &sync_file->wq, wait); >>> >>> + if (!sync_file->enabled) { >>> + fence_add_callback(sync_file->fence, &sync_file->cb, >>> + fence_check_cb_func); >>> + sync_file->enabled = true; >>> + } >> Won't this blow up completely with 2 threads polling at the same time? > Indeed, using atomic operations on enabled should fix this. No, it still would blow up without locking around fence_remove/add_callback too.. Personally I would just add the callback once, then remove it in destructor. Something like: poll: if (!atomic_xchg(&sync_file->enabled, 1)) { if (fence_add_callback(...) < 0) wake up sync_file->wq, fence is signaled } sync_file_free: if (atomic_read(&sync_file->enabled)) fence_remove_callback(...); fence_put() It's not like fence can disable hw signaling when all callbacks are removed anyway, it's harmless to keep it on the list. ~Maarten