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Restore GAP device name after GATT reset #426

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Restore GAP device name after GATT reset #426

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4 changes: 4 additions & 0 deletions src/NimBLEDevice.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -95,6 +95,8 @@ bool NimBLEDevice::m_initialized{false};
uint32_t NimBLEDevice::m_passkey{123456};
bool NimBLEDevice::m_synced{false};
ble_gap_event_listener NimBLEDevice::m_listener{};
std::string NimBLEDevice::m_deviceName{};
bool NimBLEDevice::m_deviceNameSet{false};
std::vector<NimBLEAddress> NimBLEDevice::m_whiteList{};
uint8_t NimBLEDevice::m_ownAddrType{BLE_OWN_ADDR_PUBLIC};

Expand Down Expand Up @@ -1326,6 +1328,8 @@ bool NimBLEDevice::setDeviceName(const std::string& deviceName) {
return false;
}
# endif
m_deviceName = deviceName;
m_deviceNameSet = true;
return true;
} // setDeviceName

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2 changes: 2 additions & 0 deletions src/NimBLEDevice.h
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Expand Up @@ -219,6 +219,8 @@ class NimBLEDevice {
static uint32_t m_passkey;
static ble_gap_event_listener m_listener;
static uint8_t m_ownAddrType;
static std::string m_deviceName;
static bool m_deviceNameSet;
static std::vector<NimBLEAddress> m_whiteList;
static NimBLEDeviceCallbacks* m_pDeviceCallbacks;
static NimBLEDeviceCallbacks defaultDeviceCallbacks;
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4 changes: 4 additions & 0 deletions src/NimBLEServer.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -891,6 +891,10 @@ bool NimBLEServer::resetGATT() {

ble_gatts_reset();
ble_svc_gap_init();
if (NimBLEDevice::m_deviceNameSet && !NimBLEDevice::setDeviceName(NimBLEDevice::m_deviceName)) {
return false;
}
Comment on lines +894 to +896

@coderabbitai coderabbitai Bot Jun 19, 2026

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⚠️ Potential issue | 🟠 Major | ⚖️ Poor tradeoff

Shiver me timbers! A potential race condition be lurkin' in these waters!

Arr matey, while yer logic fer reapplyin' the cached device name be sound as a Spanish doubloon, there be a concurrency concern that could make yer ship run aground:

The static members NimBLEDevice::m_deviceName and NimBLEDevice::m_deviceNameSet be accessed here without any synchronization. If some scallywag calls NimBLEDevice::setDeviceName() from another thread whilst this resetGATT() be executin', ye could have yerself a classic race condition! One thread be writin' to m_deviceName while another be readin' from it - that be a recipe fer trouble on the high seas.

Now, in most BLE applications, these operations be serialized by the nature o' the code flow. But from a library design standpoint, there be no enforcement o' this serialization, savvy?

🏴‍☠️ Possible solutions fer this concurrency concern

Option 1: Document that BLE operations must be serialized by the application (low effort, shifts responsibility to user)

Option 2: Add a mutex to protect access to the static members (higher effort, makes library thread-safe by design)

// In NimBLEDevice.h, add a static mutex
static std::mutex m_deviceNameMutex;

// In setDeviceName:
{
    std::lock_guard<std::mutex> lock(m_deviceNameMutex);
    m_deviceName = deviceName;
    m_deviceNameSet = true;
}

// In resetGATT:
std::string cachedName;
bool nameWasSet;
{
    std::lock_guard<std::mutex> lock(NimBLEDevice::m_deviceNameMutex);
    cachedName = NimBLEDevice::m_deviceName;
    nameWasSet = NimBLEDevice::m_deviceNameSet;
}
if (nameWasSet && !NimBLEDevice::setDeviceName(cachedName)) {
    return false;
}
🤖 Prompt for AI Agents 
Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In `@src/NimBLEServer.cpp` around lines 894 - 896, The static members
NimBLEDevice::m_deviceName and NimBLEDevice::m_deviceNameSet are accessed
without synchronization in the resetGATT() method, creating a potential race
condition if another thread calls setDeviceName() concurrently. To fix this, add
a static mutex member (like m_deviceNameMutex) to the NimBLEDevice class, then
protect all accesses to m_deviceName and m_deviceNameSet with std::lock_guard in
both the setDeviceName() method and the resetGATT() method. In resetGATT(),
acquire the lock, cache the values of m_deviceNameSet and m_deviceName into
local variables, release the lock, then perform the conditional call to
setDeviceName() with the cached name outside the critical section.


ble_svc_gatt_init();

for (auto svcIt = m_svcVec.begin(); svcIt != m_svcVec.end();) {
Expand Down