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cpu/esp: avoid reentrance of esp_now_recv_cb

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Although it should not be possible to reenter the function esp_now_recv_cb, this is avoided by an additional boolean variable. It can not be realized by mutex because it would reenter from same thread context.  If macro NDEBUG is not defined, an assertion is used.
This commit is contained in:
Gunar Schorcht 2019-01-03 14:01:51 +01:00
parent 9b5a77f1c4
commit a2f5c9d02f
1 changed files with 25 additions and 0 deletions
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25
cpu/esp_common/esp-now/esp_now_netdev.c
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@ -191,6 +191,8 @@ static const uint8_t _esp_now_mac[6] = { 0x82, 0x73, 0x79, 0x84, 0x79, 0x83 }; /
#endif /* ESP_NOW_UNICAST */
static bool _in_recv_cb = false;
static IRAM_ATTR void esp_now_recv_cb(const uint8_t *mac, const uint8_t *data, int len)
{
#if ESP_NOW_UNICAST
@ -200,6 +202,27 @@ static IRAM_ATTR void esp_now_recv_cb(const uint8_t *mac, const uint8_t *data, i
}
#endif
/*
* The function `esp_now_recv_cb` is executed in the context of the `wifi`
* thread. The ISRs handling the hardware interrupts from the WiFi
* interface pass events to a message queue of the `wifi` thread which is
* sequentially processed by the `wifi` thread to asynchronously execute
* callback functions such as `esp_now_recv_cb`.
*
* It should be therefore not possible to reenter function
* `esp_now_recv_cb`. To avoid inconsistencies this is checked by an
* additional boolean variable . This can not be realized by a mutex
* because `esp_now_recv_cb` would be reentered from same thread context.
* If the NDEBUG macro is undefined, an assertion is used instead for
* debugging purposes.
*/
assert(!_in_recv_cb);
if (_in_recv_cb) {
return;
}
_in_recv_cb = true;
mutex_lock(&_esp_now_dev.rx_lock);
critical_enter();
@ -212,6 +235,7 @@ static IRAM_ATTR void esp_now_recv_cb(const uint8_t *mac, const uint8_t *data, i
critical_exit();
mutex_unlock(&_esp_now_dev.rx_lock);
DEBUG("%s: buffer full, dropping incoming packet of %d bytes\n", __func__, len);
_in_recv_cb = false;
return;
}
@ -234,6 +258,7 @@ static IRAM_ATTR void esp_now_recv_cb(const uint8_t *mac, const uint8_t *data, i
critical_exit();
mutex_unlock(&_esp_now_dev.rx_lock);
_in_recv_cb = false;
}
static volatile int _esp_now_sending = 0;