From: William Breathitt Gray <vilhelm.gray@gmail.com>
To: Jonathan Cameron <jic23@kernel.org>
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
Date: Thu, 18 Feb 2021 19:32:16 +0900 [thread overview]
Message-ID: <YC5CMLuKnXbkZond@shinobu> (raw)
In-Reply-To: <20210214181146.66d43da7@archlinux>
[-- Attachment #1: Type: text/plain, Size: 6471 bytes --]
On Sun, Feb 14, 2021 at 06:11:46PM +0000, Jonathan Cameron wrote:
> On Fri, 12 Feb 2021 21:13:44 +0900
> William Breathitt Gray <vilhelm.gray@gmail.com> 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 <o.rempel@pengutronix.de>
> > Signed-off-by: William Breathitt Gray <vilhelm.gray@gmail.com>
> > ---
> > 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?
We take the events_list_lock down below so we're safe against missing an
event, but past events currently unread in the queue will be lost.
Shortening the size of the queue is inherently a destructive process if
we have more events in the current queue than can fit in the new queue.
Because we a liable to lose some events in such a case, I think it's
best to keep the behavior of this reallocation consistent and have it
provide a fresh empty queue every time, as opposed to sometimes dropping
events and sometimes not.
I also suspect an actual user would be setting the size of their queue
to the required amount before they begin watching events, rather than
adjusting it sporadically during a live operation.
> > + 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 <linux/sysfs.h>
> > #include <linux/types.h>
> >
> > +#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?
Ack.
William Breathitt Gray
> > + 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;
>
[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 833 bytes --]
next prev parent reply other threads:[~2021-02-18 11:55 UTC|newest]
Thread overview: 69+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-12 12:13 [PATCH v8 00/22] Introduce the Counter character device interface William Breathitt Gray
2021-02-12 12:13 ` [PATCH v8 01/22] docs: counter: Consolidate Counter sysfs attributes documentation William Breathitt Gray
2021-02-14 16:57 ` Jonathan Cameron
2021-02-15 11:05 ` William Breathitt Gray
2021-02-20 16:25 ` David Lechner
2021-02-12 12:13 ` [PATCH v8 02/22] docs: counter: Fix spelling William Breathitt Gray
2021-02-20 16:26 ` David Lechner
2021-02-12 12:13 ` [PATCH v8 03/22] counter: 104-quad-8: Return error when invalid mode during ceiling_write William Breathitt Gray
2021-02-20 16:30 ` David Lechner
2021-02-22 2:06 ` William Breathitt Gray
2021-02-12 12:13 ` [PATCH v8 04/22] counter: 104-quad-8: Annotate hardware config module parameter William Breathitt Gray
2021-02-12 12:13 ` [PATCH v8 05/22] counter: 104-quad-8: Add const qualifiers for quad8_preset_register_set William Breathitt Gray
2021-02-12 12:13 ` [PATCH v8 06/22] counter: 104-quad-8: Add const qualifier for functions_list array William Breathitt Gray
2021-02-12 12:13 ` [PATCH v8 07/22] counter: 104-quad-8: Add const qualifier for actions_list array William Breathitt Gray
2021-02-12 12:13 ` [PATCH v8 08/22] counter: ftm-quaddec: " William Breathitt Gray
2021-02-12 12:13 ` [PATCH v8 09/22] counter: Return error code on invalid modes William Breathitt Gray
2021-02-14 17:07 ` Jonathan Cameron
2021-02-20 16:43 ` David Lechner
2021-02-22 4:42 ` William Breathitt Gray
2021-02-12 12:13 ` [PATCH v8 10/22] counter: Standardize to ERANGE for limit exceeded errors William Breathitt Gray
2021-02-14 17:10 ` Jonathan Cameron
2021-02-16 1:26 ` William Breathitt Gray
2021-02-21 14:03 ` Jonathan Cameron
2021-02-20 16:48 ` David Lechner
2021-02-12 12:13 ` [PATCH v8 11/22] counter: Rename counter_signal_value to counter_signal_level William Breathitt Gray
2021-02-20 16:52 ` David Lechner
2021-02-12 12:13 ` [PATCH v8 12/22] counter: Rename counter_count_function to counter_function William Breathitt Gray
2021-02-14 17:13 ` Jonathan Cameron
2021-02-20 16:56 ` David Lechner
2021-02-23 5:14 ` William Breathitt Gray
2021-02-12 12:13 ` [PATCH v8 14/22] counter: Update counter.h comments to reflect sysfs internalization William Breathitt Gray
2021-02-12 12:13 ` [PATCH v8 15/22] docs: counter: Update " William Breathitt Gray
2021-02-12 12:13 ` [PATCH v8 16/22] counter: Move counter enums to uapi header William Breathitt Gray
2021-02-20 23:55 ` David Lechner
2021-02-12 12:13 ` [PATCH v8 17/22] counter: Add character device interface William Breathitt Gray
2021-02-14 18:06 ` Jonathan Cameron
2021-02-24 5:34 ` William Breathitt Gray
2021-02-15 9:24 ` Oleksij Rempel
2021-02-16 1:53 ` William Breathitt Gray
2021-02-12 12:13 ` [PATCH v8 18/22] docs: counter: Document " William Breathitt Gray
2021-02-14 17:48 ` Jonathan Cameron
2021-02-22 10:11 ` Pavel Machek
2021-02-26 0:27 ` William Breathitt Gray
2021-02-26 0:22 ` William Breathitt Gray
2021-02-12 12:13 ` [PATCH v8 19/22] counter: Implement extension*_name sysfs attributes William Breathitt Gray
2021-02-14 18:09 ` Jonathan Cameron
2021-02-19 8:51 ` William Breathitt Gray
2021-02-21 14:05 ` Jonathan Cameron
2021-02-25 23:32 ` William Breathitt Gray
2021-02-27 15:14 ` Jonathan Cameron
2021-02-12 12:13 ` [PATCH v8 20/22] counter: Implement events_queue_size sysfs attribute William Breathitt Gray
2021-02-14 18:11 ` Jonathan Cameron
2021-02-18 10:32 ` William Breathitt Gray [this message]
2021-02-21 15:51 ` Jonathan Cameron
2021-02-26 0:03 ` William Breathitt Gray
2021-02-27 0:14 ` David Lechner
2021-02-27 0:20 ` William Breathitt Gray
2021-02-27 15:18 ` Jonathan Cameron
2021-02-28 2:46 ` William Breathitt Gray
2021-02-12 12:13 ` [PATCH v8 21/22] counter: 104-quad-8: Replace mutex with spinlock William Breathitt Gray
2021-02-14 18:19 ` Jonathan Cameron
2021-02-16 2:16 ` William Breathitt Gray
2021-02-16 19:27 ` Jonathan Cameron
2021-02-18 10:16 ` William Breathitt Gray
2021-02-12 12:13 ` [PATCH v8 22/22] counter: 104-quad-8: Add IRQ support for the ACCES 104-QUAD-8 William Breathitt Gray
2021-02-14 18:24 ` Jonathan Cameron
2021-02-19 9:21 ` William Breathitt Gray
[not found] ` <3fc2580af0efd6312a64a0e107bd6fa758f0d466.1613131238.git.vilhelm.gray@gmail.com>
2021-02-14 17:32 ` [PATCH v8 13/22] counter: Internalize sysfs interface code Jonathan Cameron
2021-02-20 17:50 ` David Lechner
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=YC5CMLuKnXbkZond@shinobu \
--to=vilhelm.gray@gmail.com \
--cc=a.fatoum@pengutronix.de \
--cc=alexandre.belloni@bootlin.com \
--cc=alexandre.torgue@st.com \
--cc=david@lechnology.com \
--cc=fabrice.gasnier@st.com \
--cc=gwendal@chromium.org \
--cc=jic23@kernel.org \
--cc=kamel.bouhara@bootlin.com \
--cc=kernel@pengutronix.de \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-iio@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-stm32@st-md-mailman.stormreply.com \
--cc=mcoquelin.stm32@gmail.com \
--cc=o.rempel@pengutronix.de \
--cc=patrick.havelange@essensium.com \
--cc=syednwaris@gmail.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).