diff options
Diffstat (limited to 'libs/binder/RpcState.h')
| -rw-r--r-- | libs/binder/RpcState.h | 32 |
1 files changed, 30 insertions, 2 deletions
diff --git a/libs/binder/RpcState.h b/libs/binder/RpcState.h index dcfb5699e8..42e95e0c10 100644 --- a/libs/binder/RpcState.h +++ b/libs/binder/RpcState.h @@ -82,8 +82,29 @@ public: uint64_t address, uint32_t code, const Parcel& data, const sp<RpcSession>& session, Parcel* reply, uint32_t flags); - [[nodiscard]] status_t sendDecStrong(const sp<RpcSession::RpcConnection>& connection, - const sp<RpcSession>& session, uint64_t address); + + /** + * The ownership model here carries an implicit strong refcount whenever a + * binder is sent across processes. Since we have a local strong count in + * sp<> over these objects, we only ever need to keep one of these. So, + * typically we tell the remote process that we drop all the implicit dec + * strongs, and we hold onto the last one. 'target' here is the target + * timesRecd (the number of remaining reference counts) we wish to keep. + * Typically this should be '0' or '1'. The target is used instead of an + * explicit decrement count in order to allow multiple threads to lower the + * number of counts simultaneously. Since we only lower the count to 0 when + * a binder is deleted, targets of '1' should only be sent when the caller + * owns a local strong reference to the binder. Larger targets may be used + * for testing, and to make the function generic, but generally this should + * be avoided because it would be hard to guarantee another thread doesn't + * lower the number of held refcounts to '1'. Note also, these refcounts + * must be sent actively. If they are sent when binders are deleted, this + * can cause leaks, since even remote binders carry an implicit strong ref + * when they are sent to another process. + */ + [[nodiscard]] status_t sendDecStrongToTarget(const sp<RpcSession::RpcConnection>& connection, + const sp<RpcSession>& session, uint64_t address, + size_t target); enum class CommandType { ANY, @@ -108,6 +129,13 @@ public: */ [[nodiscard]] status_t onBinderEntering(const sp<RpcSession>& session, uint64_t address, sp<IBinder>* out); + /** + * Called on incoming binders to update refcounting information. This should + * only be called when it is done as part of making progress on a + * transaction. + */ + [[nodiscard]] status_t flushExcessBinderRefs(const sp<RpcSession>& session, uint64_t address, + const sp<IBinder>& binder); size_t countBinders(); void dump(); |