diff options
Diffstat (limited to 'drivers/gpio/gpiolib-cdev.c')
| -rw-r--r-- | drivers/gpio/gpiolib-cdev.c | 33 |
1 files changed, 22 insertions, 11 deletions
diff --git a/drivers/gpio/gpiolib-cdev.c b/drivers/gpio/gpiolib-cdev.c index bd40d717765c..12b679ca552c 100644 --- a/drivers/gpio/gpiolib-cdev.c +++ b/drivers/gpio/gpiolib-cdev.c @@ -428,6 +428,12 @@ struct line { */ struct linereq *req; unsigned int irq; + /* + * eflags is set by edge_detector_setup(), edge_detector_stop() and + * edge_detector_update(), which are themselves mutually exclusive, + * and is accessed by edge_irq_thread() and debounce_work_func(), + * which can both live with a slightly stale value. + */ u64 eflags; /* * timestamp_ns and req_seqno are accessed only by @@ -504,6 +510,8 @@ struct linereq { (GPIO_V2_LINE_FLAG_EDGE_RISING | \ GPIO_V2_LINE_FLAG_EDGE_FALLING) +#define GPIO_V2_LINE_FLAG_EDGE_BOTH GPIO_V2_LINE_EDGE_FLAGS + #define GPIO_V2_LINE_VALID_FLAGS \ (GPIO_V2_LINE_FLAG_ACTIVE_LOW | \ GPIO_V2_LINE_DIRECTION_FLAGS | \ @@ -543,6 +551,7 @@ static irqreturn_t edge_irq_thread(int irq, void *p) struct line *line = p; struct linereq *lr = line->req; struct gpio_v2_line_event le; + u64 eflags; /* Do not leak kernel stack to userspace */ memset(&le, 0, sizeof(le)); @@ -561,8 +570,8 @@ static irqreturn_t edge_irq_thread(int irq, void *p) } line->timestamp_ns = 0; - if (line->eflags == (GPIO_V2_LINE_FLAG_EDGE_RISING | - GPIO_V2_LINE_FLAG_EDGE_FALLING)) { + eflags = READ_ONCE(line->eflags); + if (eflags == GPIO_V2_LINE_FLAG_EDGE_BOTH) { int level = gpiod_get_value_cansleep(line->desc); if (level) @@ -571,10 +580,10 @@ static irqreturn_t edge_irq_thread(int irq, void *p) else /* Emit high-to-low event */ le.id = GPIO_V2_LINE_EVENT_FALLING_EDGE; - } else if (line->eflags == GPIO_V2_LINE_FLAG_EDGE_RISING) { + } else if (eflags == GPIO_V2_LINE_FLAG_EDGE_RISING) { /* Emit low-to-high event */ le.id = GPIO_V2_LINE_EVENT_RISING_EDGE; - } else if (line->eflags == GPIO_V2_LINE_FLAG_EDGE_FALLING) { + } else if (eflags == GPIO_V2_LINE_FLAG_EDGE_FALLING) { /* Emit high-to-low event */ le.id = GPIO_V2_LINE_EVENT_FALLING_EDGE; } else { @@ -643,6 +652,7 @@ static void debounce_work_func(struct work_struct *work) struct line *line = container_of(work, struct line, work.work); struct linereq *lr; int level; + u64 eflags; level = gpiod_get_raw_value_cansleep(line->desc); if (level < 0) { @@ -656,7 +666,8 @@ static void debounce_work_func(struct work_struct *work) WRITE_ONCE(line->level, level); /* -- edge detection -- */ - if (!line->eflags) + eflags = READ_ONCE(line->eflags); + if (!eflags) return; /* switch from physical level to logical - if they differ */ @@ -664,8 +675,8 @@ static void debounce_work_func(struct work_struct *work) level = !level; /* ignore edges that are not being monitored */ - if (((line->eflags == GPIO_V2_LINE_FLAG_EDGE_RISING) && !level) || - ((line->eflags == GPIO_V2_LINE_FLAG_EDGE_FALLING) && level)) + if (((eflags == GPIO_V2_LINE_FLAG_EDGE_RISING) && !level) || + ((eflags == GPIO_V2_LINE_FLAG_EDGE_FALLING) && level)) return; /* Do not leak kernel stack to userspace */ @@ -764,7 +775,7 @@ static void edge_detector_stop(struct line *line) cancel_delayed_work_sync(&line->work); WRITE_ONCE(line->sw_debounced, 0); - line->eflags = 0; + WRITE_ONCE(line->eflags, 0); /* do not change line->level - see comment in debounced_value() */ } @@ -783,7 +794,7 @@ static int edge_detector_setup(struct line *line, if (ret) return ret; } - line->eflags = eflags; + WRITE_ONCE(line->eflags, eflags); if (gpio_v2_line_config_debounced(lc, line_idx)) { debounce_period_us = gpio_v2_line_config_debounce_period(lc, line_idx); ret = debounce_setup(line, debounce_period_us); @@ -826,13 +837,13 @@ static int edge_detector_update(struct line *line, unsigned int debounce_period_us = gpio_v2_line_config_debounce_period(lc, line_idx); - if ((line->eflags == eflags) && !polarity_change && + if ((READ_ONCE(line->eflags) == eflags) && !polarity_change && (READ_ONCE(line->desc->debounce_period_us) == debounce_period_us)) return 0; /* sw debounced and still will be...*/ if (debounce_period_us && READ_ONCE(line->sw_debounced)) { - line->eflags = eflags; + WRITE_ONCE(line->eflags, eflags); WRITE_ONCE(line->desc->debounce_period_us, debounce_period_us); return 0; } |