From 9ec8cad56e47c0555a056e928e6568d543b3ae0c Mon Sep 17 00:00:00 2001 From: Mengshi Wu Date: Wed, 1 Apr 2026 19:30:04 +0800 Subject: [PATCH v1] src/device: Fix stored gatt cache DB Hash value not update MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit There is an asymmetry in behavior: when services are added during the same connection (via Service Changed indication), the persistent storage (disk) is not updated with the new DB hash, but when services are removed, it is updated. During the same connection, We check DB hash value stored at /var/lib/bluetooth//cache/. When established connection, the stored DB Hash value is A.Then we add new services, the stored DB Hash value is still A which should change to B. However, if we remove the existing services, the stored DB Hash value changed to C. When performing addition, it goes like this: discover_primary_cb() └─> gatt_db_insert_service() ← NEW service inserted into db └─> gatt_service_added() ← callback fires immediately └─> store_gatt_db() ← SAVED TO DISK (hash still OLD) ... └─> discovery_op_complete(success=true) └─> read_db_hash(op) ← sends ATT Read By Type └─> [ATT response arrives] └─> db_hash_read_cb() ├─> gatt_db_attribute_write(op->hash, ...) │ └─> hash UPDATED IN MEMORY └─> discovery_op_complete(true, 0) ├─> [no services to remove, no │ store_gatt_db called] └─> service_changed_complete() Whereas removal perform like this: discovery_op_complete(success=true) [1st call] └─> read_db_hash(op) └─> op->hash is NULL → sends ATT request → early return ... [ATT response arrives] db_hash_read_cb() └─> gatt_db_attribute_write(op->hash, ) ← hash UPDATED IN MEMORY └─> discovery_op_complete(true, 0) [2nd call] └─> read_db_hash(op) → op->hash already set → returns false └─> gatt_db_remove_service() └─> gatt_service_removed() └─> store_gatt_db() ← SAVED TO DISK (hash is NEW) There is a timing issue to update DB Hash value. The gatt_client_service_changed() callback in src/device.c is called from service_changed_complete() in gatt-client.c, which is invoked after db_hash_read_cb() has already updated the hash. Adding store_gatt_db(device) here guarantees the db is persisted with the correct, up-to-date hash for both the addition and removal cases. Upstream-Status: Backport [https://github.com/bluez/bluez/commit/0fd01e98cf94616a5c1c39749314cdd4a1654687] Signed-off-by: Mengshi Wu --- src/device.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/src/device.c b/src/device.c index 3ea683667..cfbde307b 100644 --- a/src/device.c +++ b/src/device.c @@ -6267,7 +6267,11 @@ static void gatt_client_service_changed(uint16_t start_handle, uint16_t end_handle, void *user_data) { + struct btd_device *device = user_data; + DBG("start 0x%04x, end: 0x%04x", start_handle, end_handle); + + store_gatt_db(device); } static void gatt_debug(const char *str, void *user_data) -- 2.34.1