From: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
To: Daniel Scally <djrscally@gmail.com>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
ACPI Devel Maling List <linux-acpi@vger.kernel.org>,
linux-gpio@vger.kernel.org, linux-i2c <linux-i2c@vger.kernel.org>,
Platform Driver <platform-driver-x86@vger.kernel.org>,
"open list:ACPI COMPONENT ARCHITECTURE (ACPICA)"
<devel@acpica.org>, "Rafael J. Wysocki" <rjw@rjwysocki.net>,
Len Brown <lenb@kernel.org>,
andy@kernel.org,
Mika Westerberg <mika.westerberg@linux.intel.com>,
Linus Walleij <linus.walleij@linaro.org>,
Bartosz Golaszewski <bgolaszewski@baylibre.com>,
Wolfram Sang <wsa@kernel.org>, Lee Jones <lee.jones@linaro.org>,
Hans de Goede <hdegoede@redhat.com>,
Mark Gross <mgross@linux.intel.com>,
Robert Moore <robert.moore@intel.com>,
Erik Kaneda <erik.kaneda@intel.com>,
Sakari Ailus <sakari.ailus@linux.intel.com>,
Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
Kieran Bingham <kieran.bingham@ideasonboard.com>
Subject: Re: [PATCH v2 2/7] acpi: utils: Add function to fetch dependent acpi_devices
Date: Tue, 2 Feb 2021 13:27:36 +0200 [thread overview]
Message-ID: <YBk3KDs5FCffkQp1@smile.fi.intel.com> (raw)
In-Reply-To: <d9ec0439-4323-51a2-70e7-c258fe63cd86@gmail.com>
On Tue, Feb 02, 2021 at 09:58:17AM +0000, Daniel Scally wrote:
> On 21/01/2021 21:06, Daniel Scally wrote:
> > On 21/01/2021 18:08, Rafael J. Wysocki wrote:
...
> > No problem; I'll tweak that then
>
> Slightly walking back my "No problem" here; as I understand this there's
> kinda two options:
>
> 1. Walk over the (locked) list, when a match is found unlock, run the
> callback and re-lock.
>
> The problem with that idea is unless I'm mistaken there's no guarantee
> that the .next pointer is still valid then (even using the *_safe()
> methods) because either the next or the next + 1 entry could have been
> removed whilst the list was unlocked and the callback was being ran, so
> this seems a little unsafe.
It's easy to solve.
See an example in deferred_probe_work_func().
https://elixir.bootlin.com/linux/latest/source/drivers/base/dd.c#L75
> 2. Walk over the (locked) list twice, the first time counting matching
> entries and using that to allocate a temporary buffer, then walk again
> to store the matching entries into the buffer. Finally, run the callback
> for everything in the buffer, free it and return.
>
> Obviously that's a lot less efficient than the current function, which
> isn't particularly palatable.
>
> Apologies if I've missed a better option that would work fine; but
> failing that do you still want me to go ahead and change
> acpi_walk_dep_device_list() to do this (I'd choose #2 of the above), or
> fallback to using acpi_dev_get_next_dependent_dev() described above? If
> the latter, does acpi_walk_dep_device_list() maybe need re-naming to
> make clear it's not a generalised function?
--
With Best Regards,
Andy Shevchenko
next prev parent reply other threads:[~2021-02-02 11:31 UTC|newest]
Thread overview: 98+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-18 0:34 [PATCH v2 0/7] Introduce intel_skl_int3472 driver Daniel Scally
2021-01-18 0:34 ` [PATCH v2 1/7] acpi: utils: move acpi_lpss_dep() to utils Daniel Scally
2021-01-18 7:24 ` Laurent Pinchart
2021-01-18 8:31 ` Daniel Scally
2021-01-18 12:29 ` Andy Shevchenko
2021-01-18 12:35 ` Daniel Scally
2021-01-18 12:28 ` Andy Shevchenko
2021-01-18 16:06 ` Rafael J. Wysocki
2021-01-18 16:42 ` Andy Shevchenko
2021-01-18 0:34 ` [PATCH v2 2/7] acpi: utils: Add function to fetch dependent acpi_devices Daniel Scally
2021-01-18 7:34 ` Laurent Pinchart
2021-01-18 8:37 ` Daniel Scally
2021-01-18 12:33 ` Andy Shevchenko
2021-01-18 13:37 ` Daniel Scally
2021-01-18 16:14 ` Rafael J. Wysocki
2021-01-18 20:51 ` Daniel Scally
2021-01-19 13:15 ` Rafael J. Wysocki
2021-01-19 13:28 ` Daniel Scally
2021-01-21 9:47 ` Daniel Scally
2021-01-21 11:58 ` Rafael J. Wysocki
2021-01-21 12:04 ` Daniel Scally
2021-01-21 14:39 ` Rafael J. Wysocki
2021-01-21 16:34 ` Daniel Scally
2021-01-21 18:08 ` Rafael J. Wysocki
2021-01-21 21:06 ` Daniel Scally
2021-02-02 9:58 ` Daniel Scally
2021-02-02 11:27 ` Andy Shevchenko [this message]
2021-02-02 14:02 ` Rafael J. Wysocki
2021-01-18 0:34 ` [PATCH v2 3/7] i2c: i2c-core-base: Use format macro in i2c_dev_set_name() Daniel Scally
2021-01-18 7:28 ` Laurent Pinchart
2021-01-18 12:41 ` Andy Shevchenko
2021-01-18 9:41 ` Sakari Ailus
2021-01-18 9:42 ` Sakari Ailus
2021-01-18 9:48 ` Wolfram Sang
2021-01-18 12:39 ` Andy Shevchenko
2021-01-18 0:34 ` [PATCH v2 4/7] i2c: i2c-core-acpi: Add i2c_acpi_dev_name() Daniel Scally
2021-01-18 9:18 ` Laurent Pinchart
2021-01-18 13:41 ` Andy Shevchenko
2021-01-19 13:19 ` Rafael J. Wysocki
2021-01-28 9:00 ` Wolfram Sang
2021-01-28 9:15 ` Daniel Scally
2021-01-28 9:17 ` Wolfram Sang
2021-01-28 9:22 ` Daniel Scally
2021-01-18 13:39 ` Andy Shevchenko
2021-01-18 18:43 ` Joe Perches
2021-01-18 18:56 ` Andy Shevchenko
2021-01-18 19:00 ` Joe Perches
2021-01-18 19:01 ` Andy Shevchenko
2021-01-18 0:34 ` [PATCH v2 5/7] gpio: gpiolib-acpi: Export acpi_get_gpiod() Daniel Scally
2021-01-18 7:37 ` Laurent Pinchart
2021-01-18 13:45 ` Andy Shevchenko
2021-01-18 13:46 ` Andy Shevchenko
2021-01-18 21:32 ` Daniel Scally
2021-01-18 0:34 ` [PATCH v2 6/7] platform: x86: Add intel_skl_int3472 driver Daniel Scally
2021-01-18 9:15 ` Laurent Pinchart
2021-01-18 14:46 ` Andy Shevchenko
2021-01-18 21:19 ` Daniel Scally
2021-01-19 0:11 ` Daniel Scally
2021-01-19 6:21 ` Laurent Pinchart
2021-01-19 9:35 ` Andy Shevchenko
2021-01-19 16:49 ` Laurent Pinchart
2021-01-19 9:33 ` Andy Shevchenko
2021-01-19 9:34 ` Daniel Scally
2021-01-19 16:36 ` Laurent Pinchart
2021-01-19 17:43 ` Andy Shevchenko
2021-01-20 4:18 ` Laurent Pinchart
2021-01-20 11:44 ` Andy Shevchenko
2021-01-21 21:08 ` Daniel Scally
2021-01-19 9:24 ` Andy Shevchenko
2021-01-19 10:40 ` Daniel Scally
2021-01-19 11:08 ` Andy Shevchenko
2021-01-19 16:48 ` Laurent Pinchart
2021-01-19 17:51 ` Andy Shevchenko
2021-01-20 4:21 ` Laurent Pinchart
2021-01-20 12:57 ` Andy Shevchenko
2021-01-21 0:18 ` Daniel Scally
2021-02-07 11:00 ` Daniel Scally
2021-02-07 11:56 ` Andy Shevchenko
2021-01-18 20:46 ` Daniel Scally
2021-01-19 6:19 ` Laurent Pinchart
2021-01-19 8:43 ` Daniel Scally
2021-01-19 16:33 ` Laurent Pinchart
2021-01-18 11:12 ` Barnabás Pőcze
2021-01-18 13:51 ` andriy.shevchenko
2021-01-18 14:51 ` Barnabás Pőcze
2021-01-18 15:23 ` andriy.shevchenko
2021-01-18 15:32 ` Hans de Goede
2021-01-18 15:48 ` andriy.shevchenko
2021-01-18 16:00 ` Daniel Scally
2021-01-18 16:03 ` Hans de Goede
2021-01-18 17:05 ` Laurent Pinchart
2021-01-19 10:56 ` Kieran Bingham
2021-01-19 11:11 ` Andy Shevchenko
2021-01-19 11:12 ` Daniel Scally
2021-01-18 0:34 ` [PATCH v2 7/7] mfd: Remove tps68470 MFD driver Daniel Scally
2021-01-18 7:42 ` Laurent Pinchart
2021-01-18 13:53 ` Andy Shevchenko
2021-01-18 20:07 ` Joe Perches
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