From: Pavel Machek <pavel@ucw.cz> To: Jonathan Cameron <jic23@kernel.org> Cc: William Breathitt Gray <vilhelm.gray@gmail.com>, 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 18/22] docs: counter: Document character device interface Date: Mon, 22 Feb 2021 11:11:33 +0100 [thread overview] Message-ID: <20210222101133.GB14587@amd> (raw) In-Reply-To: <20210214174819.6757e2b0@archlinux> [-- Attachment #1: Type: text/plain, Size: 2040 bytes --] Hi! > > +* COUNTER_ENABLE_EVENTS_IOCTL: > > + Enables monitoring the events specified by the Counter watches that > > + were queued by ``COUNTER_ADD_WATCH_IOCTL``. If events are already > > + enabled, the new set of watches replaces the old one. Calling this > > + ioctl also has the effect of clearing the queue of watches added by > > + ``COUNTER_ADD_WATCH_IOCTL``. > > + > > +* COUNTER_DISABLE_EVENTS_IOCTL: > > + Stops monitoring the previously enabled events. > > Is there a way to remove a watch? Is there a way to eat all kernel memory and crash the system by adding too many watches? > > +For example, the following userspace code opens ``/dev/counter0``, > > +configures the ``COUNTER_EVENT_INDEX`` event channel 0 to gather Count 0 > > +and Count 1, and prints out the data as it becomes available on the > > +character device node:: > > + > > Consider adding an example program under tools/ > > > + #include <fcntl.h> > > + #include <linux/counter.h> > > + #include <stdio.h> > > + #include <string.h> > > + #include <sys/ioctl.h> > > + #include <unistd.h> > > + > > + struct counter_watch watches[2] = { > > + { > > + .component.type = COUNTER_COMPONENT_COUNT, > > + .component.scope = COUNTER_SCOPE_COUNT, > > + .component.parent = 0, > > Good to add comments on what these elements actually are? > > + fd = open("/dev/counter0", O_RDWR); > > + > > + ioctl(fd, COUNTER_ADD_WATCH_IOCTL, watches); > > + ioctl(fd, COUNTER_ADD_WATCH_IOCTL, watches + 1); > > + ioctl(fd, COUNTER_ENABLE_EVENTS_IOCTL); > > + for (;;) { > > + read(fd, event_data, sizeof(event_data)); If this goes to tools it really should have error handling and handling of short read. Best regards, Pavel -- http://www.livejournal.com/~pavelmachek [-- Attachment #2: Digital signature --] [-- Type: application/pgp-signature, Size: 181 bytes --]
WARNING: multiple messages have this Message-ID (diff)
From: Pavel Machek <pavel@ucw.cz> To: Jonathan Cameron <jic23@kernel.org> Cc: kamel.bouhara@bootlin.com, gwendal@chromium.org, a.fatoum@pengutronix.de, david@lechnology.com, alexandre.belloni@bootlin.com, linux-iio@vger.kernel.org, patrick.havelange@essensium.com, William Breathitt Gray <vilhelm.gray@gmail.com>, mcoquelin.stm32@gmail.com, linux-kernel@vger.kernel.org, o.rempel@pengutronix.de, kernel@pengutronix.de, fabrice.gasnier@st.com, syednwaris@gmail.com, linux-stm32@st-md-mailman.stormreply.com, linux-arm-kernel@lists.infradead.org, alexandre.torgue@st.com Subject: Re: [PATCH v8 18/22] docs: counter: Document character device interface Date: Mon, 22 Feb 2021 11:11:33 +0100 [thread overview] Message-ID: <20210222101133.GB14587@amd> (raw) In-Reply-To: <20210214174819.6757e2b0@archlinux> [-- Attachment #1.1: Type: text/plain, Size: 2040 bytes --] Hi! > > +* COUNTER_ENABLE_EVENTS_IOCTL: > > + Enables monitoring the events specified by the Counter watches that > > + were queued by ``COUNTER_ADD_WATCH_IOCTL``. If events are already > > + enabled, the new set of watches replaces the old one. Calling this > > + ioctl also has the effect of clearing the queue of watches added by > > + ``COUNTER_ADD_WATCH_IOCTL``. > > + > > +* COUNTER_DISABLE_EVENTS_IOCTL: > > + Stops monitoring the previously enabled events. > > Is there a way to remove a watch? Is there a way to eat all kernel memory and crash the system by adding too many watches? > > +For example, the following userspace code opens ``/dev/counter0``, > > +configures the ``COUNTER_EVENT_INDEX`` event channel 0 to gather Count 0 > > +and Count 1, and prints out the data as it becomes available on the > > +character device node:: > > + > > Consider adding an example program under tools/ > > > + #include <fcntl.h> > > + #include <linux/counter.h> > > + #include <stdio.h> > > + #include <string.h> > > + #include <sys/ioctl.h> > > + #include <unistd.h> > > + > > + struct counter_watch watches[2] = { > > + { > > + .component.type = COUNTER_COMPONENT_COUNT, > > + .component.scope = COUNTER_SCOPE_COUNT, > > + .component.parent = 0, > > Good to add comments on what these elements actually are? > > + fd = open("/dev/counter0", O_RDWR); > > + > > + ioctl(fd, COUNTER_ADD_WATCH_IOCTL, watches); > > + ioctl(fd, COUNTER_ADD_WATCH_IOCTL, watches + 1); > > + ioctl(fd, COUNTER_ENABLE_EVENTS_IOCTL); > > + for (;;) { > > + read(fd, event_data, sizeof(event_data)); If this goes to tools it really should have error handling and handling of short read. Best regards, Pavel -- http://www.livejournal.com/~pavelmachek [-- Attachment #1.2: Digital signature --] [-- Type: application/pgp-signature, Size: 181 bytes --] [-- Attachment #2: Type: text/plain, Size: 176 bytes --] _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2021-02-22 10:14 UTC|newest] Thread overview: 139+ 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 ` William Breathitt Gray 2021-02-12 12:13 ` [PATCH v8 01/22] docs: counter: Consolidate Counter sysfs attributes documentation William Breathitt Gray 2021-02-12 12:13 ` William Breathitt Gray 2021-02-14 16:57 ` Jonathan Cameron 2021-02-14 16:57 ` Jonathan Cameron 2021-02-15 11:05 ` William Breathitt Gray 2021-02-15 11:05 ` William Breathitt Gray 2021-02-20 16:25 ` David Lechner 2021-02-20 16:25 ` David Lechner 2021-02-12 12:13 ` [PATCH v8 02/22] docs: counter: Fix spelling William Breathitt Gray 2021-02-12 12:13 ` William Breathitt Gray 2021-02-20 16:26 ` David Lechner 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 2021-02-12 12:13 ` William Breathitt Gray 2021-02-20 16:30 ` David Lechner 2021-02-20 16:30 ` David Lechner 2021-02-22 2:06 ` William Breathitt Gray 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 ` 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 ` 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 ` 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 ` William Breathitt Gray 2021-02-12 12:13 ` [PATCH v8 08/22] counter: ftm-quaddec: " William Breathitt Gray 2021-02-12 12:13 ` William Breathitt Gray 2021-02-12 12:13 ` [PATCH v8 09/22] counter: Return error code on invalid modes William Breathitt Gray 2021-02-12 12:13 ` William Breathitt Gray 2021-02-14 17:07 ` Jonathan Cameron 2021-02-14 17:07 ` Jonathan Cameron 2021-02-20 16:43 ` David Lechner 2021-02-20 16:43 ` David Lechner 2021-02-22 4:42 ` William Breathitt Gray 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 2021-02-12 12:13 ` William Breathitt Gray 2021-02-14 17:10 ` Jonathan Cameron 2021-02-14 17:10 ` Jonathan Cameron 2021-02-16 1:26 ` William Breathitt Gray 2021-02-16 1:26 ` William Breathitt Gray 2021-02-21 14:03 ` Jonathan Cameron 2021-02-21 14:03 ` Jonathan Cameron 2021-02-20 16:48 ` David Lechner 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 2021-02-12 12:13 ` William Breathitt Gray 2021-02-20 16:52 ` David Lechner 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 2021-02-12 12:13 ` William Breathitt Gray 2021-02-14 17:13 ` Jonathan Cameron 2021-02-14 17:13 ` Jonathan Cameron 2021-02-20 16:56 ` David Lechner 2021-02-20 16:56 ` David Lechner 2021-02-23 5:14 ` William Breathitt Gray 2021-02-23 5:14 ` William Breathitt Gray 2021-02-12 12:13 ` [PATCH v8 13/22] counter: Internalize sysfs interface code William Breathitt Gray 2021-02-14 17:32 ` Jonathan Cameron 2021-02-14 17:32 ` Jonathan Cameron 2021-02-20 17:50 ` David Lechner 2021-02-20 17:50 ` David Lechner 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 ` William Breathitt Gray 2021-02-12 12:13 ` [PATCH v8 15/22] docs: counter: Update " William Breathitt Gray 2021-02-12 12:13 ` William Breathitt Gray 2021-02-12 12:13 ` [PATCH v8 16/22] counter: Move counter enums to uapi header William Breathitt Gray 2021-02-12 12:13 ` William Breathitt Gray 2021-02-20 23:55 ` David Lechner 2021-02-20 23:55 ` David Lechner 2021-02-12 12:13 ` [PATCH v8 17/22] counter: Add character device interface William Breathitt Gray 2021-02-12 12:13 ` William Breathitt Gray 2021-02-14 18:06 ` Jonathan Cameron 2021-02-14 18:06 ` Jonathan Cameron 2021-02-24 5:34 ` William Breathitt Gray 2021-02-24 5:34 ` William Breathitt Gray 2021-02-15 9:24 ` Oleksij Rempel 2021-02-15 9:24 ` Oleksij Rempel 2021-02-16 1:53 ` William Breathitt Gray 2021-02-16 1:53 ` William Breathitt Gray 2021-02-12 12:13 ` [PATCH v8 18/22] docs: counter: Document " William Breathitt Gray 2021-02-12 12:13 ` William Breathitt Gray 2021-02-14 17:48 ` Jonathan Cameron 2021-02-14 17:48 ` Jonathan Cameron 2021-02-22 10:11 ` Pavel Machek [this message] 2021-02-22 10:11 ` Pavel Machek 2021-02-26 0:27 ` William Breathitt Gray 2021-02-26 0:27 ` William Breathitt Gray 2021-02-26 0:22 ` 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 2021-02-12 12:13 ` William Breathitt Gray 2021-02-14 18:09 ` Jonathan Cameron 2021-02-14 18:09 ` Jonathan Cameron 2021-02-19 8:51 ` William Breathitt Gray 2021-02-19 8:51 ` William Breathitt Gray 2021-02-21 14:05 ` Jonathan Cameron 2021-02-21 14:05 ` Jonathan Cameron 2021-02-25 23:32 ` William Breathitt Gray 2021-02-25 23:32 ` William Breathitt Gray 2021-02-27 15:14 ` Jonathan Cameron 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 2021-02-12 12:13 ` William Breathitt Gray 2021-02-14 18:11 ` Jonathan Cameron 2021-02-14 18:11 ` Jonathan Cameron 2021-02-18 10:32 ` William Breathitt Gray 2021-02-18 10:32 ` William Breathitt Gray 2021-02-21 15:51 ` Jonathan Cameron 2021-02-21 15:51 ` Jonathan Cameron 2021-02-26 0:03 ` William Breathitt Gray 2021-02-26 0:03 ` William Breathitt Gray 2021-02-27 0:14 ` David Lechner 2021-02-27 0:14 ` David Lechner 2021-02-27 0:20 ` William Breathitt Gray 2021-02-27 0:20 ` William Breathitt Gray 2021-02-27 15:18 ` Jonathan Cameron 2021-02-27 15:18 ` Jonathan Cameron 2021-02-28 2:46 ` William Breathitt Gray 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 2021-02-12 12:13 ` William Breathitt Gray 2021-02-14 18:19 ` Jonathan Cameron 2021-02-14 18:19 ` Jonathan Cameron 2021-02-16 2:16 ` William Breathitt Gray 2021-02-16 2:16 ` William Breathitt Gray 2021-02-16 19:27 ` Jonathan Cameron 2021-02-16 19:27 ` Jonathan Cameron 2021-02-18 10:16 ` William Breathitt Gray 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 2021-02-12 12:13 ` William Breathitt Gray 2021-02-14 18:24 ` Jonathan Cameron 2021-02-14 18:24 ` Jonathan Cameron 2021-02-19 9:21 ` William Breathitt Gray 2021-02-19 9:21 ` William Breathitt Gray
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