linux-kernel - Re: [PATCH 2/7] iio: buffer: iio_push_to_buffers_with_ts_unaligned() might

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Message-ID: <7f71c489-410b-4fdb-9d78-9f2835c32379@baylibre.com>
Date: Fri, 12 Sep 2025 13:40:37 -0500
From: David Lechner <dlechner@...libre.com>
To: Andy Shevchenko <andriy.shevchenko@...el.com>
Cc: Jonathan Cameron <jic23@...nel.org>, Nuno Sá
 <nuno.sa@...log.com>, Andy Shevchenko <andy@...nel.org>,
 linux-iio@...r.kernel.org, linux-kernel@...r.kernel.org,
 Daniel Lezcano <daniel.lezcano@...aro.org>,
 Andy Shevchenko <andy.shevchenko@...il.com>
Subject: Re: [PATCH 2/7] iio: buffer: iio_push_to_buffers_with_ts_unaligned()
 might_sleep()

On 9/12/25 1:10 PM, Andy Shevchenko wrote:
> On Fri, Sep 12, 2025 at 11:05:53AM -0500, David Lechner wrote:
>> Call might_sleep() in iio_push_to_buffers_with_ts_unaligned() since it
>> can allocate memory, which may sleep.
> 
> It can or does it always do?
> If the first one is correct, better to use might_sleep_if().
> 

Just below this in the function is:

	if (iio_dev_opaque->bounce_buffer_size !=  indio_dev->scan_bytes) {
		void *bb;

		bb = devm_krealloc(&indio_dev->dev,
				   iio_dev_opaque->bounce_buffer,
				   indio_dev->scan_bytes, GFP_KERNEL);
		if (!bb)
			return -ENOMEM;
		iio_dev_opaque->bounce_buffer = bb;
		iio_dev_opaque->bounce_buffer_size = indio_dev->scan_bytes;
	}


Would it make sense to move the might_sleep() inside of this
if statement rather than repeat the condition in might_sleep_if()?

devm_krealloc() is the only part of this function that might sleep.