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AP_ESC_Telem: fixed race condition in update_rpm() 

if another thread updates at the same time then we could get division
by zero
This commit is contained in:
Andrew Tridgell 2022-07-08 11:59:59 +10:00
parent 1995dbf47c
commit 0b9c5d6dc1
1 changed files with 3 additions and 2 deletions
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5
libraries/AP_ESC_Telem/AP_ESC_Telem.cpp
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@ -406,11 +406,12 @@ void AP_ESC_Telem::update_rpm(const uint8_t esc_index, const uint16_t new_rpm, c
const uint32_t now = AP_HAL::micros();
volatile AP_ESC_Telem_Backend::RpmData& rpmdata = _rpm_data[esc_index];
const auto last_update_us = rpmdata.last_update_us;
rpmdata.prev_rpm = rpmdata.rpm;
rpmdata.rpm = new_rpm;
if (now > rpmdata.last_update_us) { // cope with wrapping
rpmdata.update_rate_hz = 1.0e6f / (now - rpmdata.last_update_us);
if (now > last_update_us) { // cope with wrapping
rpmdata.update_rate_hz = 1.0e6f / (now - last_update_us);
}
rpmdata.last_update_us = now;
rpmdata.error_rate = error_rate;