diff options
| author |   Alexander Sverdlin <alexander.sverdlin@siemens.com> | 2025-03-31 18:36:40 +0200 |
|---|---|---|
| committer |   William Breathitt Gray <wbg@kernel.org> | 2025-05-03 08:45:11 +0900 |
| commit | 7351312632e831e51383f48957d47712fae791ef (patch) | |
| tree | c3b4418c12591b387d792e645c87a6d3bdbf65d8 | |
| parent | Linux 6.15-rc4 (diff) | |
| download | linux-rng-7351312632e831e51383f48957d47712fae791ef.tar.xz linux-rng-7351312632e831e51383f48957d47712fae791ef.zip | |
counter: interrupt-cnt: Protect enable/disable OPs with mutex
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: a55ebd47f21f ("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>
| -rw-r--r-- | drivers/counter/interrupt-cnt.c | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/drivers/counter/interrupt-cnt.c b/drivers/counter/interrupt-cnt.c index 949598d51575..d83848d0fe2a 100644 --- a/drivers/counter/interrupt-cnt.c +++ b/drivers/counter/interrupt-cnt.c @@ -3,12 +3,14 @@ * Copyright (c) 2021 Pengutronix, Oleksij Rempel <kernel@pengutronix.de> */ +#include <linux/cleanup.h> #include <linux/counter.h> #include <linux/gpio/consumer.h> #include <linux/interrupt.h> #include <linux/irq.h> #include <linux/mod_devicetable.h> #include <linux/module.h> +#include <linux/mutex.h> #include <linux/platform_device.h> #include <linux/types.h> @@ -19,6 +21,7 @@ struct interrupt_cnt_priv { struct gpio_desc *gpio; int irq; bool enabled; + struct mutex lock; struct counter_signal signals; struct counter_synapse synapses; struct counter_count cnts; @@ -41,6 +44,8 @@ static int interrupt_cnt_enable_read(struct counter_device *counter, { struct interrupt_cnt_priv *priv = counter_priv(counter); + guard(mutex)(&priv->lock); + *enable = priv->enabled; return 0; @@ -51,6 +56,8 @@ static int interrupt_cnt_enable_write(struct counter_device *counter, { struct interrupt_cnt_priv *priv = counter_priv(counter); + guard(mutex)(&priv->lock); + if (priv->enabled == enable) return 0; @@ -227,6 +234,8 @@ static int interrupt_cnt_probe(struct platform_device *pdev) if (ret) return ret; + mutex_init(&priv->lock); + ret = devm_counter_add(dev, counter); if (ret < 0) return dev_err_probe(dev, ret, "Failed to add counter\n"); |