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counter: 104-quad-8: Fix persistent enabled events bug
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A bug exists if the user executes a COUNTER_ADD_WATCH_IOCTL ioctl call,
and then executes a COUNTER_DISABLE_EVENTS_IOCTL ioctl call. Disabling
the events should disable the 104-QUAD-8 interrupts, but because of this
bug the interrupts are not disabling.

The reason this bug is occurring is because quad8_events_configure() is
called when COUNTER_DISABLE_EVENTS_IOCTL is handled, but the
next_irq_trigger[] array has not been cleared before it is checked in
the loop.

This patch fixes the bug by removing the next_irq_trigger array and
instead utilizing a different algorithm of walking the events_list list
for the current requested events. When a COUNTER_DISABLE_EVENTS_IOCTL is
handled, events_list will be empty and thus all device channels end up
with interrupts disabled.

Fixes: 7aa2ba0 ("counter: 104-quad-8: Add IRQ support for the ACCES 104-QUAD-8")
Cc: Syed Nayyar Waris <syednwaris@gmail.com>
Signed-off-by: William Breathitt Gray <vilhelm.gray@gmail.com>
Link: https://lore.kernel.org/r/5fd5731cec1c251acee30eefb7c19160d03c9d39.1640072891.git.vilhelm.gray@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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William Breathitt Gray authored and Greg Kroah-Hartman committed Dec 21, 2021
1 parent 60f07e7 commit c95cc0d
Showing 1 changed file with 39 additions and 43 deletions.
82 changes: 39 additions & 43 deletions drivers/counter/104-quad-8.c
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Original file line number Diff line number Diff line change
Expand Up @@ -14,6 +14,7 @@
#include <linux/interrupt.h>
#include <linux/isa.h>
#include <linux/kernel.h>
#include <linux/list.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/types.h>
Expand Down Expand Up @@ -44,7 +45,6 @@ MODULE_PARM_DESC(irq, "ACCES 104-QUAD-8 interrupt line numbers");
* @ab_enable: array of A and B inputs enable configurations
* @preset_enable: array of set_to_preset_on_index attribute configurations
* @irq_trigger: array of current IRQ trigger function configurations
* @next_irq_trigger: array of next IRQ trigger function configurations
* @synchronous_mode: array of index function synchronous mode configurations
* @index_polarity: array of index function polarity configurations
* @cable_fault_enable: differential encoder cable status enable configurations
Expand All @@ -61,7 +61,6 @@ struct quad8 {
unsigned int ab_enable[QUAD8_NUM_COUNTERS];
unsigned int preset_enable[QUAD8_NUM_COUNTERS];
unsigned int irq_trigger[QUAD8_NUM_COUNTERS];
unsigned int next_irq_trigger[QUAD8_NUM_COUNTERS];
unsigned int synchronous_mode[QUAD8_NUM_COUNTERS];
unsigned int index_polarity[QUAD8_NUM_COUNTERS];
unsigned int cable_fault_enable;
Expand Down Expand Up @@ -390,7 +389,6 @@ static int quad8_action_read(struct counter_device *counter,
}

enum {
QUAD8_EVENT_NONE = -1,
QUAD8_EVENT_CARRY = 0,
QUAD8_EVENT_COMPARE = 1,
QUAD8_EVENT_CARRY_BORROW = 2,
Expand All @@ -402,34 +400,49 @@ static int quad8_events_configure(struct counter_device *counter)
struct quad8 *const priv = counter->priv;
unsigned long irq_enabled = 0;
unsigned long irqflags;
size_t channel;
struct counter_event_node *event_node;
unsigned int next_irq_trigger;
unsigned long ior_cfg;
unsigned long base_offset;

spin_lock_irqsave(&priv->lock, irqflags);

/* Enable interrupts for the requested channels, disable for the rest */
for (channel = 0; channel < QUAD8_NUM_COUNTERS; channel++) {
if (priv->next_irq_trigger[channel] == QUAD8_EVENT_NONE)
continue;
list_for_each_entry(event_node, &counter->events_list, l) {
switch (event_node->event) {
case COUNTER_EVENT_OVERFLOW:
next_irq_trigger = QUAD8_EVENT_CARRY;
break;
case COUNTER_EVENT_THRESHOLD:
next_irq_trigger = QUAD8_EVENT_COMPARE;
break;
case COUNTER_EVENT_OVERFLOW_UNDERFLOW:
next_irq_trigger = QUAD8_EVENT_CARRY_BORROW;
break;
case COUNTER_EVENT_INDEX:
next_irq_trigger = QUAD8_EVENT_INDEX;
break;
default:
/* should never reach this path */
spin_unlock_irqrestore(&priv->lock, irqflags);
return -EINVAL;
}

if (priv->irq_trigger[channel] != priv->next_irq_trigger[channel]) {
/* Save new IRQ function configuration */
priv->irq_trigger[channel] = priv->next_irq_trigger[channel];
/* Skip configuration if it is the same as previously set */
if (priv->irq_trigger[event_node->channel] == next_irq_trigger)
continue;

/* Load configuration to I/O Control Register */
ior_cfg = priv->ab_enable[channel] |
priv->preset_enable[channel] << 1 |
priv->irq_trigger[channel] << 3;
base_offset = priv->base + 2 * channel + 1;
outb(QUAD8_CTR_IOR | ior_cfg, base_offset);
}
/* Save new IRQ function configuration */
priv->irq_trigger[event_node->channel] = next_irq_trigger;

/* Reset next IRQ trigger function configuration */
priv->next_irq_trigger[channel] = QUAD8_EVENT_NONE;
/* Load configuration to I/O Control Register */
ior_cfg = priv->ab_enable[event_node->channel] |
priv->preset_enable[event_node->channel] << 1 |
priv->irq_trigger[event_node->channel] << 3;
base_offset = priv->base + 2 * event_node->channel + 1;
outb(QUAD8_CTR_IOR | ior_cfg, base_offset);

/* Enable IRQ line */
irq_enabled |= BIT(channel);
irq_enabled |= BIT(event_node->channel);
}

outb(irq_enabled, priv->base + QUAD8_REG_INDEX_INTERRUPT);
Expand All @@ -442,35 +455,20 @@ static int quad8_events_configure(struct counter_device *counter)
static int quad8_watch_validate(struct counter_device *counter,
const struct counter_watch *watch)
{
struct quad8 *const priv = counter->priv;
struct counter_event_node *event_node;

if (watch->channel > QUAD8_NUM_COUNTERS - 1)
return -EINVAL;

switch (watch->event) {
case COUNTER_EVENT_OVERFLOW:
if (priv->next_irq_trigger[watch->channel] == QUAD8_EVENT_NONE)
priv->next_irq_trigger[watch->channel] = QUAD8_EVENT_CARRY;
else if (priv->next_irq_trigger[watch->channel] != QUAD8_EVENT_CARRY)
return -EINVAL;
return 0;
case COUNTER_EVENT_THRESHOLD:
if (priv->next_irq_trigger[watch->channel] == QUAD8_EVENT_NONE)
priv->next_irq_trigger[watch->channel] = QUAD8_EVENT_COMPARE;
else if (priv->next_irq_trigger[watch->channel] != QUAD8_EVENT_COMPARE)
return -EINVAL;
return 0;
case COUNTER_EVENT_OVERFLOW_UNDERFLOW:
if (priv->next_irq_trigger[watch->channel] == QUAD8_EVENT_NONE)
priv->next_irq_trigger[watch->channel] = QUAD8_EVENT_CARRY_BORROW;
else if (priv->next_irq_trigger[watch->channel] != QUAD8_EVENT_CARRY_BORROW)
return -EINVAL;
return 0;
case COUNTER_EVENT_INDEX:
if (priv->next_irq_trigger[watch->channel] == QUAD8_EVENT_NONE)
priv->next_irq_trigger[watch->channel] = QUAD8_EVENT_INDEX;
else if (priv->next_irq_trigger[watch->channel] != QUAD8_EVENT_INDEX)
return -EINVAL;
list_for_each_entry(event_node, &counter->next_events_list, l)
if (watch->channel == event_node->channel &&
watch->event != event_node->event)
return -EINVAL;
return 0;
default:
return -EINVAL;
Expand Down Expand Up @@ -1183,8 +1181,6 @@ static int quad8_probe(struct device *dev, unsigned int id)
outb(QUAD8_CTR_IOR, base_offset + 1);
/* Disable index function; negative index polarity */
outb(QUAD8_CTR_IDR, base_offset + 1);
/* Initialize next IRQ trigger function configuration */
priv->next_irq_trigger[i] = QUAD8_EVENT_NONE;
}
/* Disable Differential Encoder Cable Status for all channels */
outb(0xFF, base[id] + QUAD8_DIFF_ENCODER_CABLE_STATUS);
Expand Down

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