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sensors/lsm6ds3trc: move the FIFO drain buffer off the stack

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The worker declared its drain buffer as int16_t raw[FIFO_MAX_WORDS], and
FIFO_MAX_WORDS scales with CONFIG_SENSORS_LSM6DS3TRC_FIFO_WATERMARK.

At the Kconfig default watermark of 8 that is 192 bytes and nobody ever
noticed.  At the watermark this collar uses, 250, it is 6000 bytes inside
an 8192-byte HPWORK stack -- 73% of it, before the call frame and the
whole I2C stack underneath.  Any board raising the watermark walks into a
stack overflow in a shared work queue, which is about the worst place to
find one.

Allocated once at registration so the drain path stays allocation-free,
and the driver fails registration cleanly if it cannot get the memory.

Assisted-by: Claude:claude-opus-5
Signed-off-by: Felipe Moura <moura.fmo@gmail.com>
This commit is contained in:
Felipe Moura 2026-09-19 17:58:33 -03:00 • committed by Xiang Xiao
parent 159ef8105b
commit 08ee713b4d
1 changed files with 28 additions and 1 deletions
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29
drivers/sensors/lsm6ds3trc_uorb.c
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@ -216,6 +216,21 @@ struct lsm6ds3trc_dev_s
* (both), 0 if neither is */
enum lsm6ds3trc_odr_e fifo_odr; /* Shared ODR currently driving
* FIFO_CTRL5 */
FAR int16_t *fifo_raw; /* Drain buffer, FIFO_MAX_WORDS entries.
*
* On the heap, not the stack.
* FIFO_MAX_WORDS scales with
* CONFIG_SENSORS_LSM6DS3TRC_FIFO_
* WATERMARK, so at the watermark this
* board uses the old on-stack array was
* 6000 bytes inside an 8192-byte HPWORK
* stack -- 73% of it, before the call
* frame and the whole I2C stack below
* it. The Kconfig default watermark of
* 8 needs only 192 bytes, which is
* presumably why this was never hit.
* Allocated once at registration so the
* drain path stays allocation free. */
#endif
};
@ -840,7 +855,7 @@ static int accel_thread(int argc, char **argv)
static void lsm6ds3trc_fifo_worker_body(FAR struct lsm6ds3trc_dev_s *dev)
{
uint8_t status[2];
int16_t raw[FIFO_MAX_WORDS];
FAR int16_t *raw = dev->fifo_raw;
int16_t raw_temp;
float temp_c;
uint16_t diff_words;
@ -1567,6 +1582,18 @@ int lsm6ds3trc_register(FAR struct i2c_master_s *i2c, uint8_t addr,
}
priv->i2c = i2c;
#ifdef CONFIG_SENSORS_LSM6DS3TRC_FIFO
priv->fifo_raw = kmm_malloc(FIFO_MAX_WORDS * sizeof(int16_t));
if (priv->fifo_raw == NULL)
{
snerr("ERROR: no memory for the %d-byte FIFO drain buffer\n",
(int)(FIFO_MAX_WORDS * sizeof(int16_t)));
kmm_free(priv);
return -ENOMEM;
}
#endif
priv->addr = addr;
priv->interrupt_mode = config->attach != NULL;
priv->int_pin = config->int_pin;