From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-15.5 required=3.0 tests=BAYES_00,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_2 autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id EAF8FC433E6 for ; Sun, 14 Feb 2021 18:12:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BF5CC64E4E for ; Sun, 14 Feb 2021 18:12:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229829AbhBNSMf (ORCPT ); Sun, 14 Feb 2021 13:12:35 -0500 Received: from mail.kernel.org ([198.145.29.99]:55282 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229758AbhBNSMd (ORCPT ); Sun, 14 Feb 2021 13:12:33 -0500 Received: from archlinux (cpc108967-cmbg20-2-0-cust86.5-4.cable.virginm.net [81.101.6.87]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 551FD64E29; Sun, 14 Feb 2021 18:11:50 +0000 (UTC) Date: Sun, 14 Feb 2021 18:11:46 +0000 From: Jonathan Cameron To: William Breathitt Gray Cc: kernel@pengutronix.de, linux-stm32@st-md-mailman.stormreply.com, a.fatoum@pengutronix.de, kamel.bouhara@bootlin.com, gwendal@chromium.org, alexandre.belloni@bootlin.com, david@lechnology.com, linux-iio@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, syednwaris@gmail.com, patrick.havelange@essensium.com, fabrice.gasnier@st.com, mcoquelin.stm32@gmail.com, alexandre.torgue@st.com, o.rempel@pengutronix.de Subject: Re: [PATCH v8 20/22] counter: Implement events_queue_size sysfs attribute Message-ID: <20210214181146.66d43da7@archlinux> In-Reply-To: <013b2b8682ddc3c85038083e6d5567696b6254b3.1613131238.git.vilhelm.gray@gmail.com> References: <013b2b8682ddc3c85038083e6d5567696b6254b3.1613131238.git.vilhelm.gray@gmail.com> X-Mailer: Claws Mail 3.17.8 (GTK+ 2.24.33; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 12 Feb 2021 21:13:44 +0900 William Breathitt Gray wrote: > The events_queue_size sysfs attribute provides a way for users to > dynamically configure the Counter events queue size for the Counter > character device interface. The size is in number of struct > counter_event data structures. The number of elements will be rounded-up > to a power of 2 due to a requirement of the kfifo_alloc function called > during reallocation of the queue. > > Cc: Oleksij Rempel > Signed-off-by: William Breathitt Gray > --- > Documentation/ABI/testing/sysfs-bus-counter | 8 +++++++ > drivers/counter/counter-chrdev.c | 23 +++++++++++++++++++ > drivers/counter/counter-chrdev.h | 2 ++ > drivers/counter/counter-sysfs.c | 25 +++++++++++++++++++++ > 4 files changed, 58 insertions(+) > > diff --git a/Documentation/ABI/testing/sysfs-bus-counter b/Documentation/ABI/testing/sysfs-bus-counter > index 847e96f19d19..f6cb2a8b08a7 100644 > --- a/Documentation/ABI/testing/sysfs-bus-counter > +++ b/Documentation/ABI/testing/sysfs-bus-counter > @@ -212,6 +212,14 @@ Description: > both edges: > Any state transition. > > +What: /sys/bus/counter/devices/counterX/events_queue_size > +KernelVersion: 5.13 > +Contact: linux-iio@vger.kernel.org > +Description: > + Size of the Counter events queue in number of struct > + counter_event data structures. The number of elements will be > + rounded-up to a power of 2. > + > What: /sys/bus/counter/devices/counterX/name > KernelVersion: 5.2 > Contact: linux-iio@vger.kernel.org > diff --git a/drivers/counter/counter-chrdev.c b/drivers/counter/counter-chrdev.c > index 16f02df7f73d..53eea894e13f 100644 > --- a/drivers/counter/counter-chrdev.c > +++ b/drivers/counter/counter-chrdev.c > @@ -375,6 +375,29 @@ void counter_chrdev_remove(struct counter_device *const counter) > cdev_del(&counter->chrdev); > } > > +int counter_chrdev_realloc_queue(struct counter_device *const counter, > + size_t queue_size) > +{ > + int err; > + DECLARE_KFIFO_PTR(events, struct counter_event); > + unsigned long flags; > + > + /* Allocate new events queue */ > + err = kfifo_alloc(&events, queue_size, GFP_ATOMIC); Is there any potential for losing events? > + if (err) > + return err; > + > + raw_spin_lock_irqsave(&counter->events_list_lock, flags); > + > + /* Swap in new events queue */ > + kfifo_free(&counter->events); > + counter->events.kfifo = events.kfifo; > + > + raw_spin_unlock_irqrestore(&counter->events_list_lock, flags); > + > + return 0; > +} > + > static int counter_get_data(struct counter_device *const counter, > const struct counter_comp_node *const comp_node, > u64 *const value) > diff --git a/drivers/counter/counter-chrdev.h b/drivers/counter/counter-chrdev.h > index cf5a318fe540..ff7fb0191852 100644 > --- a/drivers/counter/counter-chrdev.h > +++ b/drivers/counter/counter-chrdev.h > @@ -12,5 +12,7 @@ > int counter_chrdev_add(struct counter_device *const counter, > const dev_t counter_devt); > void counter_chrdev_remove(struct counter_device *const counter); > +int counter_chrdev_realloc_queue(struct counter_device *const counter, > + size_t queue_size); > > #endif /* _COUNTER_CHRDEV_H_ */ > diff --git a/drivers/counter/counter-sysfs.c b/drivers/counter/counter-sysfs.c > index 0cb3dba950bc..9abc821a3871 100644 > --- a/drivers/counter/counter-sysfs.c > +++ b/drivers/counter/counter-sysfs.c > @@ -13,6 +13,7 @@ > #include > #include > > +#include "counter-chrdev.h" > #include "counter-sysfs.h" > > /** > @@ -737,12 +738,30 @@ static int counter_num_counts_read(struct counter_device *counter, u8 *val) > return 0; > } > > +static int counter_events_queue_size_read(struct counter_device *counter, > + u64 *val) > +{ > + *val = counter->events.kfifo.mask + 1; kfifo_size() rather than open coding it? > + return 0; > +} > + > +static int counter_events_queue_size_write(struct counter_device *counter, > + u64 val) > +{ > + return counter_chrdev_realloc_queue(counter, val); > +} > + > static struct counter_comp counter_num_signals_comp = > COUNTER_COMP_DEVICE_U8("num_signals", counter_num_signals_read, NULL); > > static struct counter_comp counter_num_counts_comp = > COUNTER_COMP_DEVICE_U8("num_counts", counter_num_counts_read, NULL); > > +static struct counter_comp counter_events_queue_size_comp = > + COUNTER_COMP_DEVICE_U64("events_queue_size", > + counter_events_queue_size_read, > + counter_events_queue_size_write); > + > static int counter_sysfs_attr_add(struct counter_device *const counter, > struct counter_attribute_group *group) > { > @@ -781,6 +800,12 @@ static int counter_sysfs_attr_add(struct counter_device *const counter, > if (err < 0) > return err; > > + /* Create num_counts attribute */ > + err = counter_attr_create(dev, group, &counter_events_queue_size_comp, > + scope, NULL); > + if (err < 0) > + return err; > + > /* Create an attribute for each extension */ > for (i = 0; i < counter->num_ext; i++) { > ext = counter->ext + i;