sascha/esphome
1
0
Fork 0
mirror of https://github.com/esphome/esphome.git synced 2025-10-04 11:02:19 +01:00
Code Issues Releases Wiki Activity

fix underflow

Browse Source
This commit is contained in:
J. Nick Koston
2025-09-28 18:41:20 -05:00
parent e07af13bef
commit d65b1fad67
1 changed files with 23 additions and 17 deletions
Download Patch File Download Diff File Expand all files Collapse all files

40
esphome/components/usb_host/usb_host_client.cpp
View File

@@ -361,24 +361,30 @@ TransferRequest *USBClient::get_trq_() {
uint16_t mask = this->trq_in_use_.load(std::memory_order_relaxed); uint16_t mask = this->trq_in_use_.load(std::memory_order_relaxed);
// Find first available slot (bit = 0) and try to claim it atomically // Find first available slot (bit = 0) and try to claim it atomically
for (size_t i = 0; i < MAX_REQUESTS; i++) { // We use a while loop to allow retrying the same slot after CAS failure
if (!(mask & (1U << i))) { size_t i = 0;
// Slot i appears available, try to claim it atomically while (i < MAX_REQUESTS) {
uint16_t expected = mask; if (mask & (1U << i)) {
uint16_t desired = mask | (1U << i); // Set bit i to mark as in-use // Slot is in use, move to next slot
i++;
if (this->trq_in_use_.compare_exchange_weak(expected, desired, std::memory_order_acquire, continue;
std::memory_order_relaxed)) {
// Successfully claimed slot i - prepare the TransferRequest
auto *trq = &this->requests_[i];
trq->transfer->context = trq;
trq->transfer->device_handle = this->device_handle_;
return trq;
}
// Another thread claimed this slot, retry with updated mask
mask = expected;
i--; // Retry the same index with new mask value
} }
// Slot i appears available, try to claim it atomically
uint16_t expected = mask;
uint16_t desired = mask | (1U << i); // Set bit i to mark as in-use
if (this->trq_in_use_.compare_exchange_weak(expected, desired, std::memory_order_acquire,
std::memory_order_relaxed)) {
// Successfully claimed slot i - prepare the TransferRequest
auto *trq = &this->requests_[i];
trq->transfer->context = trq;
trq->transfer->device_handle = this->device_handle_;
return trq;
}
// Another thread claimed this slot, retry with updated mask
// Don't increment i - retry the same slot with the updated mask
mask = expected;
} }
ESP_LOGE(TAG, "Too many requests queued (all %d slots in use)", MAX_REQUESTS); ESP_LOGE(TAG, "Too many requests queued (all %d slots in use)", MAX_REQUESTS);