From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757135AbbJVKGi (ORCPT ); Thu, 22 Oct 2015 06:06:38 -0400 Received: from mout.kundenserver.de ([212.227.17.24]:60651 "EHLO mout.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756988AbbJVKGg (ORCPT ); Thu, 22 Oct 2015 06:06:36 -0400 From: Arnd Bergmann To: Eric Auger Cc: eric.auger@st.com, alex.williamson@redhat.com, b.reynal@virtualopensystems.com, linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org, christoffer.dall@linaro.org, linux-kernel@vger.kernel.org, patches@linaro.org Subject: Re: [PATCH v2 1/6] vfio: platform: add capability to register a reset function Date: Thu, 22 Oct 2015 12:06:02 +0200 Message-ID: <4039449.LR9NiiaAaC@wuerfel> User-Agent: KMail/4.11.5 (Linux/3.16.0-10-generic; KDE/4.11.5; x86_64; ; ) In-Reply-To: <1445506922-6005-2-git-send-email-eric.auger@linaro.org> References: <1445506922-6005-1-git-send-email-eric.auger@linaro.org> <1445506922-6005-2-git-send-email-eric.auger@linaro.org> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" X-Provags-ID: V03:K0:sWiI+Y8zkozTbJZ5q5I5QAxpJu1KDijPoG7K1Gfi223CjFNs36W SfeNg6pUOnIj7BTi5AeXM0J0cHF1Pyuk2lA+x6Vh2YFm1NsalWtCMwKVc/5a7w8wSDDXh9X Ndvd/FuDRquleLEAqn2w8Kon0qIZzjxuN8rELGM+O6EDQY5WL5QyJ9ak5xxF0ZyvyOlnb8x /9g6u+6XjiQkwHb9gn0Pw== X-UI-Out-Filterresults: notjunk:1;V01:K0:utMzLVEAUs0=:2aA+6t/e+iLPmnXbNeLHEx JrqIOKDdAyVNFM7Cwc3n36fYsK+nb0bZ9J/NGwa2IhhlkLGn2XPus4MpsiUDixHyCg39yxKdc scBZRmlUaPEf7nzfb3kgiB7g7YrHmiPZ+JMwAwvlkkQPSaN3DaL55ysafnzQuYw6ff1gySus2 0Vtt2vDgNGKXHMsTR6kzcMBjDwHUoc5DeDhnW+0yuNmw9fPJYsXI86ZzKCINkirvo/to/A5JH VnxsJ9SyfyPMBEX8LbXqINhWG2wTm6miK1rZiXflZTbnpPnDafD+uaYtRk15kWCFdoTSG3OeX SPp6bjIqX4NyP4ToXfRp/edaDIIrJEPNerdw9p1C/+6VFkMvg7bXzMeA9Jb6LzOqe1CWOqlFA 0A1fYMu4vpZvLgdY6y1QN4umJAOnxdm6HTDXH1q5mFWphUjr6ZXVZkcmidPja01Og5vVtud4a BArl1W6tOGo42U4dBzhht5QM4RYKEu60yTzvjbu3A935SW7fTEblEPkr7i81zvHMr6uEQuKhP uiBhiW1KFyLjbFwD7B9g2S0nvq1uCIG/9oyvPibPHtGW0elvjZX5VwrrwMu4livSkAZdaw90U 12HosJk665Ui9iVvdoT+EfXRWzzRl/MCCgxChk4YbJbh+VbvzJPNcNfTJRu9v9/bNpZLJNqz7 bVzAmXULI8piWmrVW6xYqahaae1U5i5TwnTsV/KLcQ36Yq4nMQwX5opTDFiefDOFEE2VZKAyJ mQSV8VP390a0nTMo Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thursday 22 October 2015 11:41:57 Eric Auger wrote: > In preparation for subsequent changes in reset function lookup, > lets introduce a dynamic list of reset combos (compat string, > reset module, reset function). The list can be populated/voided with > two new functions, vfio_platform_register/unregister_reset. Those are > not yet used in this patch. > > Signed-off-by: Eric Auger Looks correct to me now, just a little style comments. > drivers/vfio/platform/vfio_platform_common.c | 77 +++++++++++++++++++++++++++ > drivers/vfio/platform/vfio_platform_private.h | 7 +++ > 2 files changed, 84 insertions(+) > > diff --git a/drivers/vfio/platform/vfio_platform_common.c b/drivers/vfio/platform/vfio_platform_common.c > index e43efb5..52a4c7b 100644 > --- a/drivers/vfio/platform/vfio_platform_common.c > +++ b/drivers/vfio/platform/vfio_platform_common.c > @@ -23,6 +23,15 @@ > > #include "vfio_platform_private.h" > > +struct vfio_platform_reset_node { > + struct list_head link; > + char *compat; > + struct module *owner; > + vfio_platform_reset_fn_t reset; > +}; > + > +static LIST_HEAD(reset_list); > +static DEFINE_MUTEX(reset_lock); > static DEFINE_MUTEX(driver_lock); I wonder if having a single mutex here would be enough. If you don't expect drivers to register/unregister a lot, you could just use driver_lock here as well. > static const struct vfio_platform_reset_combo reset_lookup_table[] = { > @@ -573,3 +582,71 @@ struct vfio_platform_device *vfio_platform_remove_common(struct device *dev) > return vdev; > } > EXPORT_SYMBOL_GPL(vfio_platform_remove_common); > + > +int vfio_platform_register_reset(struct module *reset_owner, > + const char *compat, > + vfio_platform_reset_fn_t reset) > +{ > + struct vfio_platform_reset_node *node, *iter; > + bool found = false; > + > + mutex_lock(&reset_lock); > + list_for_each_entry(iter, &reset_list, link) { > + if (!strcmp(iter->compat, compat)) { > + found = true; > + break; > + } > + } > + if (found) { > + mutex_unlock(&reset_lock); > + return -EINVAL; > + } This seems to be an unnecesssary safeguard. I would not bother with the search, or otherwise do a WARN_ON here. > + node = kmalloc(sizeof(*node), GFP_KERNEL); > + if (!node) { > + mutex_unlock(&reset_lock); > + return -ENOMEM; > + } > + > + node->compat = kstrdup(compat, GFP_KERNEL); > + if (!node->compat) { > + kfree(node); > + mutex_unlock(&reset_lock); > + return -ENOMEM; > + } If you hold a lock, it's better to use a goto for handling errors and put the unlock and kfree there. I think it can be avoided entirely here though: It should be safe to define the interface as keeping a reference on the string and not do a kstrdup here. I would expect users to pass a string literal. We could even go as far as defining the entire interface as a shim, like #define vfio_platform_register_reset(__compat, __reset) \ static struct vfio_platform_reset_node __reset ## _node = { \ .owner = THIS_MODULE, \ .compat = __compat, \ .reset = __reset, \ }; \ __vfio_platform_register_reset(&__reset ## node); to make the function really simple. Arnd