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Alexander Sverdlin 8d47a03544 counter: interrupt-cnt: Protect enable/disable OPs with mutex

[ Upstream commit 7351312632 ]

Enable/disable seems to be racy on SMP, consider the following scenario:

CPU0					CPU1

interrupt_cnt_enable_write(true)
{
	if (priv->enabled == enable)
		return 0;

	if (enable) {
		priv->enabled = true;
					interrupt_cnt_enable_write(false)
					{
						if (priv->enabled == enable)
							return 0;

						if (enable) {
							priv->enabled = true;
							enable_irq(priv->irq);
						} else {
							disable_irq(priv->irq)
							priv->enabled = false;
						}
		enable_irq(priv->irq);
	} else {
		disable_irq(priv->irq);
		priv->enabled = false;
	}

The above would result in priv->enabled == false, but IRQ left enabled.
Protect both write (above race) and read (to propagate the value on SMP)
callbacks with a mutex.

Signed-off-by: Alexander Sverdlin <alexander.sverdlin@siemens.com>
Fixes: a55ebd47f2 ("counter: add IRQ or GPIO based counter")
Acked-by: Oleksij Rempel <o.rempel@pengutronix.de>
Link: https://lore.kernel.org/r/20250331163642.2382651-1-alexander.sverdlin@siemens.com
Signed-off-by: William Breathitt Gray <wbg@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

2025-06-19 15:32:12 +02:00

104-quad-8.c

move asm/unaligned.h to linux/unaligned.h

2024-10-02 17:23:23 -04:00

counter-chrdev.c

[tree-wide] finally take no_llseek out

2024-09-27 08:18:43 -07:00

counter-chrdev.h

counter: Add character device interface

2021-10-17 10:53:52 +01:00

counter-core.c

counter: constify the struct device_type usage