From: Adrian Ambrozewicz <aambrozewicz@nvidia.com>
To: "Paul E. McKenney" <paulmck@kernel.org>
Cc: Bartosz Golaszewski <brgl@kernel.org>,
Linus Walleij <linusw@kernel.org>,
Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com>,
Kent Gibson <warthog618@gmail.com>,
Herve Codina <herve.codina@bootlin.com>,
Jia Jia <physicalmtea@gmail.com>,
Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
linux-gpio@vger.kernel.org, linux-kernel@vger.kernel.org,
stable@vger.kernel.org
Subject: Re: [PATCH 1/6] gpiolib: wait for pending label frees before cleaning up desc_srcu
Date: Fri, 16 Oct 2026 10:46:48 +0300 [thread overview]
Message-ID: <20261016074704.1860749-1-aambrozewicz@nvidia.com> (raw)
In-Reply-To: <40aa9190-df23-449e-b547-165b8826db8d@paulmck-laptop>
On Mon, Oct 12, 2026 at 08:46:03AM -0700, Paul E. McKenney wrote:
> From an SRCU viewpoint:
>
> Reviewed-by: Paul E. McKenney <paulmck@kernel.org>
>
> In this, I am assuming that the comment is correct, and that we only
> need to wait for pending frees, not readers.
Thanks, Paul. The comment holds: desc_srcu is embedded in struct
gpio_device, and every reader reaches it through desc->gdev of a
descriptor in that device's array, which is freed along with it. The
readers (the line info of the character device,
gpiochip_dup_line_label(), debugfs and the gpiod_*() print helpers)
all work on a descriptor or chip they hold a reference to, so none of
them can still be inside a read section when the last reference is
dropped and gpiodev_release() runs. Only the queued label frees can be
left at that point.
Adrian
next prev parent reply other threads:[~2026-10-16 7:47 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-10-12 13:49 [PATCH 0/6] gpiolib: fix chip removal with lines still requested from user space Adrian Ambrozewicz
2026-10-12 13:49 ` [PATCH 1/6] gpiolib: wait for pending label frees before cleaning up desc_srcu Adrian Ambrozewicz
2026-10-12 15:46 ` Paul E. McKenney
2026-10-16 7:46 ` Adrian Ambrozewicz [this message]
2026-10-12 20:42 ` Andy Shevchenko
2026-10-16 7:46 ` Adrian Ambrozewicz
2026-10-12 13:49 ` [PATCH 2/6] gpiolib: free the label of lines released after their chip was removed Adrian Ambrozewicz
2026-10-13 15:38 ` Andy Shevchenko
2026-10-16 7:46 ` Adrian Ambrozewicz
2026-10-12 13:49 ` [PATCH 3/6] gpiolib: cdev: do not free line IRQs again after the chip is removed Adrian Ambrozewicz
2026-10-13 15:44 ` Andy Shevchenko
2026-10-16 7:46 ` Adrian Ambrozewicz
2026-10-12 13:49 ` [PATCH 4/6] gpiolib: cdev: don't sleep in the SRCU read section in read() Adrian Ambrozewicz
2026-10-13 15:48 ` Andy Shevchenko
2026-10-16 7:46 ` Adrian Ambrozewicz
2026-10-12 13:49 ` [PATCH 5/6] gpiolib: cdev: don't leak the IRQ name when the chip is removed Adrian Ambrozewicz
2026-10-13 15:59 ` Andy Shevchenko
2026-10-16 7:46 ` Adrian Ambrozewicz
2026-10-12 13:50 ` [PATCH 6/6] gpiolib: let the character device free its IRQs first on chip removal Adrian Ambrozewicz
2026-10-13 16:05 ` Andy Shevchenko
2026-10-16 7:46 ` Adrian Ambrozewicz
2026-10-15 12:57 ` [PATCH 0/6] gpiolib: fix chip removal with lines still requested from user space Bartosz Golaszewski
2026-10-16 7:46 ` Adrian Ambrozewicz
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