From mboxrd@z Thu Jan 1 00:00:00 1970 From: Peter Zijlstra Subject: Re: [PATCH v2 04/11] locking/ww_mutex: Set use_ww_ctx even when locking without a context Date: Tue, 6 Dec 2016 16:25:37 +0100 Message-ID: <20161206152537.GV3045@worktop.programming.kicks-ass.net> References: <1480601214-26583-1-git-send-email-nhaehnle@gmail.com> <1480601214-26583-5-git-send-email-nhaehnle@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Return-path: Received: from merlin.infradead.org (merlin.infradead.org [IPv6:2001:4978:20e::2]) by gabe.freedesktop.org (Postfix) with ESMTPS id 9FF0A6E142 for ; Tue, 6 Dec 2016 15:25:49 +0000 (UTC) Content-Disposition: inline In-Reply-To: <1480601214-26583-5-git-send-email-nhaehnle@gmail.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" To: Nicolai =?iso-8859-1?Q?H=E4hnle?= Cc: Maarten Lankhorst , Nicolai =?iso-8859-1?Q?H=E4hnle?= , linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, Ingo Molnar List-Id: dri-devel@lists.freedesktop.org T24gVGh1LCBEZWMgMDEsIDIwMTYgYXQgMDM6MDY6NDdQTSArMDEwMCwgTmljb2xhaSBIw6Robmxl IHdyb3RlOgoKPiBAQCAtNjQwLDEwICs2NDAsMTEgQEAgX19tdXRleF9sb2NrX2NvbW1vbihzdHJ1 Y3QgbXV0ZXggKmxvY2ssIGxvbmcgc3RhdGUsIHVuc2lnbmVkIGludCBzdWJjbGFzcywKPiAgCXN0 cnVjdCBtdXRleF93YWl0ZXIgd2FpdGVyOwo+ICAJdW5zaWduZWQgbG9uZyBmbGFnczsKPiAgCWJv b2wgZmlyc3QgPSBmYWxzZTsKPiAtCXN0cnVjdCB3d19tdXRleCAqd3c7Cj4gIAlpbnQgcmV0Owo+ ICAKPiAtCWlmICh1c2Vfd3dfY3R4KSB7Cj4gKwlpZiAodXNlX3d3X2N0eCAmJiB3d19jdHgpIHsK PiArCQlzdHJ1Y3Qgd3dfbXV0ZXggKnd3Owo+ICsKPiAgCQl3dyA9IGNvbnRhaW5lcl9vZihsb2Nr LCBzdHJ1Y3Qgd3dfbXV0ZXgsIGJhc2UpOwo+ICAJCWlmICh1bmxpa2VseSh3d19jdHggPT0gUkVB RF9PTkNFKHd3LT5jdHgpKSkKPiAgCQkJcmV0dXJuIC1FQUxSRUFEWTsKClNvIEkgZG9uJ3Qgc2Vl IHRoZSBwb2ludCBvZiByZW1vdmluZyAqd3cgZnJvbSB0aGUgZnVuY3Rpb24gc2NvcGUsIHdlIGNh bgpzdGlsbCBjb21wdXRlIHRoYXQgY29udGFpbmVyX29mKCkgZXZlbiBpZiAhd3dfY3R4LCByaWdo dD8gVGhhdCB3b3VsZApzYWZlIGEgdG9uIG9mIGNodXJuIGJlbG93LCBhZGRpbmcgYWxsIHRob3Nl IHN0cnVjdCB3d19tdXRleCBkZWNsYXJhdGlvbnMKYW5kIGNvbnRhaW5lcl9vZigpIGNhc3RzLgoK KGFuZCBub3RlIHRoYXQgdGhlIGNvbnRhaW5lcl9vZigpIGlzIGEgZmFuY3kgTk8tT1AgYmVjYXVz ZSBiYXNlIGlzIHRoZQpmaXJzdCBtZW1iZXIpLgoKPiBAQCAtNjU2LDggKzY1NywxMiBAQCBfX211 dGV4X2xvY2tfY29tbW9uKHN0cnVjdCBtdXRleCAqbG9jaywgbG9uZyBzdGF0ZSwgdW5zaWduZWQg aW50IHN1YmNsYXNzLAo+ICAJICAgIG11dGV4X29wdGltaXN0aWNfc3Bpbihsb2NrLCB3d19jdHgs IHVzZV93d19jdHgsIGZhbHNlKSkgewo+ICAJCS8qIGdvdCB0aGUgbG9jaywgeWF5ISAqLwo+ICAJ CWxvY2tfYWNxdWlyZWQoJmxvY2stPmRlcF9tYXAsIGlwKTsKPiAtCQlpZiAodXNlX3d3X2N0eCkK PiArCQlpZiAodXNlX3d3X2N0eCAmJiB3d19jdHgpIHsKPiArCQkJc3RydWN0IHd3X211dGV4ICp3 dzsKPiArCj4gKwkJCXd3ID0gY29udGFpbmVyX29mKGxvY2ssIHN0cnVjdCB3d19tdXRleCwgYmFz ZSk7Cj4gIAkJCXd3X211dGV4X3NldF9jb250ZXh0X2Zhc3RwYXRoKHd3LCB3d19jdHgpOwo+ICsJ CX0KPiAgCQlwcmVlbXB0X2VuYWJsZSgpOwo+ICAJCXJldHVybiAwOwo+ICAJfQo+IEBAIC03MDIs NyArNzA3LDcgQEAgX19tdXRleF9sb2NrX2NvbW1vbihzdHJ1Y3QgbXV0ZXggKmxvY2ssIGxvbmcg c3RhdGUsIHVuc2lnbmVkIGludCBzdWJjbGFzcywKPiAgCQkJZ290byBlcnI7Cj4gIAkJfQo+ICAK PiAtCQlpZiAodXNlX3d3X2N0eCAmJiB3d19jdHgtPmFjcXVpcmVkID4gMCkgewo+ICsJCWlmICh1 c2Vfd3dfY3R4ICYmIHd3X2N0eCAmJiB3d19jdHgtPmFjcXVpcmVkID4gMCkgewo+ICAJCQlyZXQg PSBfX3d3X211dGV4X2xvY2tfY2hlY2tfc3RhbXAobG9jaywgd3dfY3R4KTsKPiAgCQkJaWYgKHJl dCkKPiAgCQkJCWdvdG8gZXJyOwo+IEBAIC03NDIsOCArNzQ3LDEyIEBAIF9fbXV0ZXhfbG9ja19j b21tb24oc3RydWN0IG11dGV4ICpsb2NrLCBsb25nIHN0YXRlLCB1bnNpZ25lZCBpbnQgc3ViY2xh c3MsCj4gIAkvKiBnb3QgdGhlIGxvY2sgLSBjbGVhbnVwIGFuZCByZWpvaWNlISAqLwo+ICAJbG9j a19hY3F1aXJlZCgmbG9jay0+ZGVwX21hcCwgaXApOwo+ICAKPiAtCWlmICh1c2Vfd3dfY3R4KQo+ ICsJaWYgKHVzZV93d19jdHggJiYgd3dfY3R4KSB7Cj4gKwkJc3RydWN0IHd3X211dGV4ICp3dzsK PiArCj4gKwkJd3cgPSBjb250YWluZXJfb2YobG9jaywgc3RydWN0IHd3X211dGV4LCBiYXNlKTsK PiAgCQl3d19tdXRleF9zZXRfY29udGV4dF9zbG93cGF0aCh3dywgd3dfY3R4KTsKPiArCX0KPiAg Cj4gIAlzcGluX3VubG9ja19tdXRleCgmbG9jay0+d2FpdF9sb2NrLCBmbGFncyk7Cj4gIAlwcmVl bXB0X2VuYWJsZSgpOwoKQWxsIHRoYXQgdGhlbiByZXZlcnRzIHRvOgoKLQlpZiAodXNlX3d3X2N0 eCkKKwlpZiAodXNlX3d3X2N0eCAmJiB3d19jdHgpCgoKX19fX19fX19fX19fX19fX19fX19fX19f X19fX19fX19fX19fX19fX19fX19fX18KZHJpLWRldmVsIG1haWxpbmcgbGlzdApkcmktZGV2ZWxA bGlzdHMuZnJlZWRlc2t0b3Aub3JnCmh0dHBzOi8vbGlzdHMuZnJlZWRlc2t0b3Aub3JnL21haWxt YW4vbGlzdGluZm8vZHJpLWRldmVsCg== From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753567AbcLFP0A (ORCPT ); Tue, 6 Dec 2016 10:26:00 -0500 Received: from merlin.infradead.org ([205.233.59.134]:36852 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753493AbcLFPZ6 (ORCPT ); Tue, 6 Dec 2016 10:25:58 -0500 Date: Tue, 6 Dec 2016 16:25:37 +0100 From: Peter Zijlstra To: Nicolai =?iso-8859-1?Q?H=E4hnle?= Cc: linux-kernel@vger.kernel.org, Nicolai =?iso-8859-1?Q?H=E4hnle?= , Ingo Molnar , Maarten Lankhorst , Daniel Vetter , Chris Wilson , dri-devel@lists.freedesktop.org Subject: Re: [PATCH v2 04/11] locking/ww_mutex: Set use_ww_ctx even when locking without a context Message-ID: <20161206152537.GV3045@worktop.programming.kicks-ass.net> References: <1480601214-26583-1-git-send-email-nhaehnle@gmail.com> <1480601214-26583-5-git-send-email-nhaehnle@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <1480601214-26583-5-git-send-email-nhaehnle@gmail.com> User-Agent: Mutt/1.5.22.1 (2013-10-16) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Dec 01, 2016 at 03:06:47PM +0100, Nicolai Hähnle wrote: > @@ -640,10 +640,11 @@ __mutex_lock_common(struct mutex *lock, long state, unsigned int subclass, > struct mutex_waiter waiter; > unsigned long flags; > bool first = false; > - struct ww_mutex *ww; > int ret; > > - if (use_ww_ctx) { > + if (use_ww_ctx && ww_ctx) { > + struct ww_mutex *ww; > + > ww = container_of(lock, struct ww_mutex, base); > if (unlikely(ww_ctx == READ_ONCE(ww->ctx))) > return -EALREADY; So I don't see the point of removing *ww from the function scope, we can still compute that container_of() even if !ww_ctx, right? That would safe a ton of churn below, adding all those struct ww_mutex declarations and container_of() casts. (and note that the container_of() is a fancy NO-OP because base is the first member). > @@ -656,8 +657,12 @@ __mutex_lock_common(struct mutex *lock, long state, unsigned int subclass, > mutex_optimistic_spin(lock, ww_ctx, use_ww_ctx, false)) { > /* got the lock, yay! */ > lock_acquired(&lock->dep_map, ip); > - if (use_ww_ctx) > + if (use_ww_ctx && ww_ctx) { > + struct ww_mutex *ww; > + > + ww = container_of(lock, struct ww_mutex, base); > ww_mutex_set_context_fastpath(ww, ww_ctx); > + } > preempt_enable(); > return 0; > } > @@ -702,7 +707,7 @@ __mutex_lock_common(struct mutex *lock, long state, unsigned int subclass, > goto err; > } > > - if (use_ww_ctx && ww_ctx->acquired > 0) { > + if (use_ww_ctx && ww_ctx && ww_ctx->acquired > 0) { > ret = __ww_mutex_lock_check_stamp(lock, ww_ctx); > if (ret) > goto err; > @@ -742,8 +747,12 @@ __mutex_lock_common(struct mutex *lock, long state, unsigned int subclass, > /* got the lock - cleanup and rejoice! */ > lock_acquired(&lock->dep_map, ip); > > - if (use_ww_ctx) > + if (use_ww_ctx && ww_ctx) { > + struct ww_mutex *ww; > + > + ww = container_of(lock, struct ww_mutex, base); > ww_mutex_set_context_slowpath(ww, ww_ctx); > + } > > spin_unlock_mutex(&lock->wait_lock, flags); > preempt_enable(); All that then reverts to: - if (use_ww_ctx) + if (use_ww_ctx && ww_ctx)