From: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
To: Bartosz Golaszewski <brgl@bgdev.pl>
Cc: Linux ARM <linux-arm-kernel@lists.infradead.org>,
Lars-Peter Clausen <lars@metafoo.de>,
linux-iio <linux-iio@vger.kernel.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Michal Simek <michal.simek@xilinx.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Bartosz Golaszewski <bgolaszewski@baylibre.com>,
Guenter Roeck <linux@roeck-us.net>,
Peter Meerwald-Stadler <pmeerw@pmeerw.net>,
Hartmut Knaack <knaack.h@gmx.de>,
Jonathan Cameron <jic23@kernel.org>
Subject: Re: [PATCH v7 1/3] devres: provide devm_krealloc()
Date: Tue, 18 Aug 2020 11:25:00 +0300 [thread overview]
Message-ID: <20200818082500.GB1891694@smile.fi.intel.com> (raw)
In-Reply-To: <CAMRc=MdaaWhV_ZKHgWy_Gxkp=jMuZcwqpoE8Ya_84n9ZT5O31A@mail.gmail.com>
On Mon, Aug 17, 2020 at 10:02:05PM +0200, Bartosz Golaszewski wrote:
> On Mon, Aug 17, 2020 at 7:43 PM Andy Shevchenko
> <andriy.shevchenko@linux.intel.com> wrote:
> > On Mon, Aug 17, 2020 at 07:05:33PM +0200, Bartosz Golaszewski wrote:
> > > From: Bartosz Golaszewski <bgolaszewski@baylibre.com>
...
> > > +static struct devres *to_devres(void *data)
> > > +{
> > > + return (struct devres *)((u8 *)data - ALIGN(sizeof(struct devres),
> > > + ARCH_KMALLOC_MINALIGN));
> >
> > Do you really need both explicit castings?
> >
>
> Yeah, we can probably drop the (struct devres *) here.
void * -> u8 * here is also not needed, it is considered byte access IIRC.
> > > +}
...
> > - hasn't gone while you run a ksize()?
> At some point you need to draw a line. In the end: how do you
> guarantee a devres buffer hasn't been freed when you're using it? In
> my comment to the previous version of this patch I clarified that we
> need to protect all modifications of the devres linked list - we must
> not realloc a chunk that contains the links without taking the
> spinlock but also we must not call alloc() funcs with GFP_KERNEL with
> spinlock taken. The issue we could run into is: someone modifies the
> linked list by adding/removing other managed resources, not modifying
> this one.
>
> The way this function works now guarantees it but other than that:
> it's up to the users to not free memory they're actively using.
Thanks for clarification. I agree.
--
With Best Regards,
Andy Shevchenko
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next prev parent reply other threads:[~2020-08-18 8:41 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-17 17:05 [PATCH v7 0/3] devres: provide and use devm_krealloc() Bartosz Golaszewski
2020-08-17 17:05 ` [PATCH v7 1/3] devres: provide devm_krealloc() Bartosz Golaszewski
2020-08-17 17:39 ` Andy Shevchenko
2020-08-17 20:02 ` Bartosz Golaszewski
2020-08-18 8:25 ` Andy Shevchenko [this message]
2020-08-18 16:27 ` Bartosz Golaszewski
2020-08-18 17:10 ` Andy Shevchenko
2020-08-18 18:13 ` Bartosz Golaszewski
2020-08-19 9:14 ` Andy Shevchenko
2020-08-17 17:05 ` [PATCH v7 2/3] hwmon: pmbus: use more devres helpers Bartosz Golaszewski
2020-08-17 17:05 ` [PATCH v7 3/3] iio: adc: xilinx-xadc: use devm_krealloc() Bartosz Golaszewski
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