From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from smtp2.goneo.de ([85.220.129.33]:58496 "EHLO smtp2.goneo.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965693AbcIWNfQ (ORCPT ); Fri, 23 Sep 2016 09:35:16 -0400 Content-Type: text/plain; charset=us-ascii Mime-Version: 1.0 (Mac OS X Mail 6.6 \(1510\)) Subject: Re: [PATCH 06/11] dma-buf: Introduce fence_get_rcu_safe() From: Markus Heiser In-Reply-To: <20160923125932.GG3988@dvetter-linux.ger.corp.intel.com> Date: Fri, 23 Sep 2016 15:34:32 +0200 Cc: Chris Wilson , dri-devel@lists.freedesktop.org, intel-gfx@lists.freedesktop.org, Daniel Vetter , Sumit Semwal , linux-media@vger.kernel.org, linaro-mm-sig@lists.linaro.org Content-Transfer-Encoding: 8BIT Message-Id: References: <20160829070834.22296-1-chris@chris-wilson.co.uk> <20160829070834.22296-6-chris@chris-wilson.co.uk> <20160923125932.GG3988@dvetter-linux.ger.corp.intel.com> To: Daniel Vetter Sender: linux-media-owner@vger.kernel.org List-ID: Am 23.09.2016 um 14:59 schrieb Daniel Vetter : >> >> /** >> - * fence_put - decreases refcount of the fence >> - * @fence: [in] fence to reduce refcount of >> + * fence_get_rcu_safe - acquire a reference to an RCU tracked fence >> + * @fence: [in] pointer to fence to increase refcount of >> + * >> + * Function returns NULL if no refcount could be obtained, or the fence. >> + * This function handles acquiring a reference to a fence that may be >> + * reallocated within the RCU grace period (such as with SLAB_DESTROY_BY_RCU), >> + * so long as the caller is using RCU on the pointer to the fence. >> + * >> + * An alternative mechanism is to employ a seqlock to protect a bunch of >> + * fences, such as used by struct reservation_object. When using a seqlock, >> + * the seqlock must be taken before and checked after a reference to the >> + * fence is acquired (as shown here). >> + * >> + * The caller is required to hold the RCU read lock. > > Would be good to cross reference the various fence_get functions a bit > better in the docs. But since the docs aren't yet pulled into the rst/html > output, that doesn't matter that much Hi Daniel ... I'am working on ;-) * http://return42.github.io/sphkerneldoc/linux_src_doc/include/linux/fence_h.html -- Markus From mboxrd@z Thu Jan 1 00:00:00 1970 From: Markus Heiser Subject: Re: [PATCH 06/11] dma-buf: Introduce fence_get_rcu_safe() Date: Fri, 23 Sep 2016 15:34:32 +0200 Message-ID: References: <20160829070834.22296-1-chris@chris-wilson.co.uk> <20160829070834.22296-6-chris@chris-wilson.co.uk> <20160923125932.GG3988@dvetter-linux.ger.corp.intel.com> Mime-Version: 1.0 (Mac OS X Mail 6.6 \(1510\)) Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Return-path: Received: from smtp2.goneo.de (smtp2.goneo.de [85.220.129.33]) by gabe.freedesktop.org (Postfix) with ESMTPS id 5711E6E027 for ; Fri, 23 Sep 2016 13:35:15 +0000 (UTC) In-Reply-To: <20160923125932.GG3988@dvetter-linux.ger.corp.intel.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" To: Daniel Vetter Cc: Daniel Vetter , intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linaro-mm-sig@lists.linaro.org, linux-media@vger.kernel.org List-Id: dri-devel@lists.freedesktop.org CkFtIDIzLjA5LjIwMTYgdW0gMTQ6NTkgc2NocmllYiBEYW5pZWwgVmV0dGVyIDxkYW5pZWxAZmZ3 bGwuY2g+OgoKPj4gCj4+IC8qKgo+PiAtICogZmVuY2VfcHV0IC0gZGVjcmVhc2VzIHJlZmNvdW50 IG9mIHRoZSBmZW5jZQo+PiAtICogQGZlbmNlOglbaW5dCWZlbmNlIHRvIHJlZHVjZSByZWZjb3Vu dCBvZgo+PiArICogZmVuY2VfZ2V0X3JjdV9zYWZlICAtIGFjcXVpcmUgYSByZWZlcmVuY2UgdG8g YW4gUkNVIHRyYWNrZWQgZmVuY2UKPj4gKyAqIEBmZW5jZToJW2luXQlwb2ludGVyIHRvIGZlbmNl IHRvIGluY3JlYXNlIHJlZmNvdW50IG9mCj4+ICsgKgo+PiArICogRnVuY3Rpb24gcmV0dXJucyBO VUxMIGlmIG5vIHJlZmNvdW50IGNvdWxkIGJlIG9idGFpbmVkLCBvciB0aGUgZmVuY2UuCj4+ICsg KiBUaGlzIGZ1bmN0aW9uIGhhbmRsZXMgYWNxdWlyaW5nIGEgcmVmZXJlbmNlIHRvIGEgZmVuY2Ug dGhhdCBtYXkgYmUKPj4gKyAqIHJlYWxsb2NhdGVkIHdpdGhpbiB0aGUgUkNVIGdyYWNlIHBlcmlv ZCAoc3VjaCBhcyB3aXRoIFNMQUJfREVTVFJPWV9CWV9SQ1UpLAo+PiArICogc28gbG9uZyBhcyB0 aGUgY2FsbGVyIGlzIHVzaW5nIFJDVSBvbiB0aGUgcG9pbnRlciB0byB0aGUgZmVuY2UuCj4+ICsg Kgo+PiArICogQW4gYWx0ZXJuYXRpdmUgbWVjaGFuaXNtIGlzIHRvIGVtcGxveSBhIHNlcWxvY2sg dG8gcHJvdGVjdCBhIGJ1bmNoIG9mCj4+ICsgKiBmZW5jZXMsIHN1Y2ggYXMgdXNlZCBieSBzdHJ1 Y3QgcmVzZXJ2YXRpb25fb2JqZWN0LiBXaGVuIHVzaW5nIGEgc2VxbG9jaywKPj4gKyAqIHRoZSBz ZXFsb2NrIG11c3QgYmUgdGFrZW4gYmVmb3JlIGFuZCBjaGVja2VkIGFmdGVyIGEgcmVmZXJlbmNl IHRvIHRoZQo+PiArICogZmVuY2UgaXMgYWNxdWlyZWQgKGFzIHNob3duIGhlcmUpLgo+PiArICoK Pj4gKyAqIFRoZSBjYWxsZXIgaXMgcmVxdWlyZWQgdG8gaG9sZCB0aGUgUkNVIHJlYWQgbG9jay4K PiAKPiBXb3VsZCBiZSBnb29kIHRvIGNyb3NzIHJlZmVyZW5jZSB0aGUgdmFyaW91cyBmZW5jZV9n ZXQgZnVuY3Rpb25zIGEgYml0Cj4gYmV0dGVyIGluIHRoZSBkb2NzLiBCdXQgc2luY2UgdGhlIGRv Y3MgYXJlbid0IHlldCBwdWxsZWQgaW50byB0aGUgcnN0L2h0bWwKPiBvdXRwdXQsIHRoYXQgZG9l c24ndCBtYXR0ZXIgdGhhdCBtdWNoCgpIaSBEYW5pZWwgLi4uIEknYW0gd29ya2luZyBvbiA7LSkK CiogaHR0cDovL3JldHVybjQyLmdpdGh1Yi5pby9zcGhrZXJuZWxkb2MvbGludXhfc3JjX2RvYy9p bmNsdWRlL2xpbnV4L2ZlbmNlX2guaHRtbAoKLS0gTWFya3VzIC0tCl9fX19fX19fX19fX19fX19f X19fX19fX19fX19fX19fX19fX19fX19fX19fX19fCmRyaS1kZXZlbCBtYWlsaW5nIGxpc3QKZHJp LWRldmVsQGxpc3RzLmZyZWVkZXNrdG9wLm9yZwpodHRwczovL2xpc3RzLmZyZWVkZXNrdG9wLm9y Zy9tYWlsbWFuL2xpc3RpbmZvL2RyaS1kZXZlbAo=