From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Mehta, Sohil" Subject: Re: [PATCH v3 2/2] iommu/amd: Add basic debugfs infrastructure for AMD IOMMU Date: Wed, 18 Apr 2018 07:27:28 +0000 Message-ID: <1524036520.2747.31.camel@intel.com> References: <152302042701.47565.17954813724758433858.stgit@sosxen2.amd.com> <152302067362.47565.628887796165116844.stgit@sosxen2.amd.com> <1523664612.2747.13.camel@intel.com> <1524031122.4031.5.camel@hxt-semitech.com> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Return-path: In-Reply-To: <1524031122.4031.5.camel-PT9Dzx9SjPiXmMXjJBpWqg@public.gmane.org> Content-Language: en-US Content-ID: <1D07B9325DA45C4BAB58AB717D0D9AC3-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Errors-To: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org To: "shunyong.yang-PT9Dzx9SjPiXmMXjJBpWqg@public.gmane.org" , "gary.hook-5C7GfCeVMHo@public.gmane.org" , "iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org" , "ghook-5C7GfCeVMHo@public.gmane.org" Cc: "linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" List-Id: iommu@lists.linux-foundation.org T24gV2VkLCAyMDE4LTA0LTE4IGF0IDA1OjU4ICswMDAwLCBZYW5nLCBTaHVueW9uZyB3cm90ZToN Cj4gSGksIEdhcnkgYW5kIFNvaGlsLA0KPiANCj4gT24gVHVlLCAyMDE4LTA0LTE3IGF0IDEzOjM4 IC0wNDAwLCBIb29rLCBHYXJ5IHdyb3RlOg0KPiA+IE9uIDQvMTMvMjAxOCA4OjA4IFBNLCBNZWh0 YSwgU29oaWwgd3JvdGU6DQo+ID4gPsKgDQo+ID4gPiBPbiBGcmksIDIwMTgtMDQtMDYgYXQgMDg6 MTcgLTA1MDAsIEdhcnkgUiBIb29rIHdyb3RlOg0KPiA+ID4gPsKgDQo+ID4gPiA+IMKgwqANCj4g PiA+ID4gKw0KPiA+ID4gPiArdm9pZCBhbWRfaW9tbXVfZGVidWdmc19zZXR1cChzdHJ1Y3QgYW1k X2lvbW11ICppb21tdSkNCj4gPiA+ID4gK3sNCj4gPiA+ID4gK8KgY2hhciBuYW1lW01BWF9OQU1F X0xFTiArIDFdOw0KPiA+ID4gPiArwqBzdHJ1Y3QgZGVudHJ5ICpkX3RvcDsNCj4gPiA+ID4gKw0K PiA+ID4gPiArwqBpZiAoIWRlYnVnZnNfaW5pdGlhbGl6ZWQoKSkNCj4gPiA+IFByb2JhYmx5IG5v dCBuZWVkZWQuDQo+ID4gUmlnaHQuDQo+IA0KPiBXaGVuIHdpbGwgdGhpcyBjaGVjayBpcyBuZWVk ZWQ/DQo+IElNTywgdGhpcyBmdW5jdGlvbiBpcyB0byBjaGVjayBkZWJ1Z2ZzIHJlYWR5IHN0YXR1 cyBiZWZvcmUgd2Ugd2FudCB0bw0KPiB1c2UgZGVidWdmcy4gSSBqdXN0IHdhbnQgdG8gdW5kZXJz dGFuZCB3aGVuIHdlIHNob3VsZCB1c2UNCj4gZGVidWdmc19pbml0aWFsaXplZCgpOw0KPiANCg0K WW91IGFyZSByaWdodCBkZWJ1Z2ZzX2luaXRpYWxpemVkKCkgY2FuIGJlIHVzZWQgdG8gY2hlY2sg aWYgZGVidWdmcyBpcw0KcmVhZHkuIEhvd2V2ZXIgaW4gdGhpcyBjYXNlIHdlIGNhbiBhbHNvIHJl bHkgb24gZGVidWdmc19jcmVhdGVfZGlyKCkNCndoaWNoIGlzIGNhbGxlZCBpbiBpb21tdV9kZWJ1 ZnNfc2V0dXAoKS4NCg0KZGVidWdmc19jcmVhdGVfZGlyKCkgc2F5czoNCg0KwqAqIElmIGRlYnVn ZnMgaXMgbm90IGVuYWJsZWQgaW4gdGhlIGtlcm5lbCwgdGhlIHZhbHVlIC0lRU5PREVWIHdpbGwg YmUNCsKgKiByZXR1cm5lZC4NCg0KU29oaWwNCg0KPiBUaGFua3MuDQo+IFNodW55b25nLg0KPiAN Cj4gPsKgDQo+ID4gPsKgDQo+ID4gPsKgDQo+ID4gPiA+wqANCj4gPiA+ID4gK8KgwqDCoMKgwqDC oMKgwqDCoHJldHVybjsNCj4gPiA+ID4gKw0KPiA+ID4gPiArwqBtdXRleF9sb2NrKCZhbWRfaW9t bXVfZGVidWdmc19sb2NrKTsNCj4gPiA+ID4gK8KgaWYgKCFhbWRfaW9tbXVfZGVidWdmcykgew0K PiA+ID4gPiArwqDCoMKgwqDCoMKgwqDCoMKgZF90b3AgPSBpb21tdV9kZWJ1Z2ZzX3NldHVwKCk7 DQo+ID4gPiA+ICvCoMKgwqDCoMKgwqDCoMKgwqBpZiAoZF90b3ApDQo+ID4gPiA+ICvCoMKgwqDC oMKgwqDCoMKgwqDCoMKgwqDCoMKgwqDCoMKgYW1kX2lvbW11X2RlYnVnZnMgPQ0KPiA+ID4gPiBk ZWJ1Z2ZzX2NyZWF0ZV9kaXIoImFtZCIsIGRfdG9wKTsNCj4gPiA+ID4gK8KgfQ0KPiA+ID4gPiAr wqBtdXRleF91bmxvY2soJmFtZF9pb21tdV9kZWJ1Z2ZzX2xvY2spOwpfX19fX19fX19fX19fX19f X19fX19fX19fX19fX19fX19fX19fX19fX19fX19fXwppb21tdSBtYWlsaW5nIGxpc3QKaW9tbXVA bGlzdHMubGludXgtZm91bmRhdGlvbi5vcmcKaHR0cHM6Ly9saXN0cy5saW51eGZvdW5kYXRpb24u b3JnL21haWxtYW4vbGlzdGluZm8vaW9tbXU= From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753213AbeDRH1c (ORCPT ); Wed, 18 Apr 2018 03:27:32 -0400 Received: from mga05.intel.com ([192.55.52.43]:24374 "EHLO mga05.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753112AbeDRH1a (ORCPT ); Wed, 18 Apr 2018 03:27:30 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.48,464,1517904000"; d="scan'208";a="47859825" From: "Mehta, Sohil" To: "shunyong.yang@hxt-semitech.com" , "gary.hook@amd.com" , "iommu@lists.linux-foundation.org" , "ghook@amd.com" CC: "linux-kernel@vger.kernel.org" Subject: Re: [PATCH v3 2/2] iommu/amd: Add basic debugfs infrastructure for AMD IOMMU Thread-Topic: [PATCH v3 2/2] iommu/amd: Add basic debugfs infrastructure for AMD IOMMU Thread-Index: AQHT04THDyVaDNNW7k6hYyQjJLsxvaQFs/wAgADO9QCAABkcAA== Date: Wed, 18 Apr 2018 07:27:28 +0000 Message-ID: <1524036520.2747.31.camel@intel.com> References: <152302042701.47565.17954813724758433858.stgit@sosxen2.amd.com> <152302067362.47565.628887796165116844.stgit@sosxen2.amd.com> <1523664612.2747.13.camel@intel.com> <1524031122.4031.5.camel@hxt-semitech.com> In-Reply-To: <1524031122.4031.5.camel@hxt-semitech.com> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [172.25.110.4] Content-Type: text/plain; charset="utf-8" Content-ID: <1D07B9325DA45C4BAB58AB717D0D9AC3@intel.com> MIME-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from base64 to 8bit by mail.home.local id w3I7Rljc010564 On Wed, 2018-04-18 at 05:58 +0000, Yang, Shunyong wrote: > Hi, Gary and Sohil, > > On Tue, 2018-04-17 at 13:38 -0400, Hook, Gary wrote: > > On 4/13/2018 8:08 PM, Mehta, Sohil wrote: > > >  > > > On Fri, 2018-04-06 at 08:17 -0500, Gary R Hook wrote: > > > >  > > > >    > > > > + > > > > +void amd_iommu_debugfs_setup(struct amd_iommu *iommu) > > > > +{ > > > > + char name[MAX_NAME_LEN + 1]; > > > > + struct dentry *d_top; > > > > + > > > > + if (!debugfs_initialized()) > > > Probably not needed. > > Right. > > When will this check is needed? > IMO, this function is to check debugfs ready status before we want to > use debugfs. I just want to understand when we should use > debugfs_initialized(); > You are right debugfs_initialized() can be used to check if debugfs is ready. However in this case we can also rely on debugfs_create_dir() which is called in iommu_debufs_setup(). debugfs_create_dir() says:  * If debugfs is not enabled in the kernel, the value -%ENODEV will be  * returned. Sohil > Thanks. > Shunyong. > > >  > > >  > > >  > > > >  > > > > +         return; > > > > + > > > > + mutex_lock(&amd_iommu_debugfs_lock); > > > > + if (!amd_iommu_debugfs) { > > > > +         d_top = iommu_debugfs_setup(); > > > > +         if (d_top) > > > > +                 amd_iommu_debugfs = > > > > debugfs_create_dir("amd", d_top); > > > > + } > > > > + mutex_unlock(&amd_iommu_debugfs_lock);