Clarify `IStorageSession`'s `WOULD_BLOCK` behavior
Add an explanation to `IStorageSession`'s doc comment of how the
interface uses `WOULD_BLOCK` error returns.
Test: none
Bug: 278779487
Change-Id: Ib2fa6e5bdf594f62370f2eb8852cf76f1d0c7dde
diff --git a/staging/security/see/storage/aidl/android/hardware/security/see/storage/ISecureStorage.aidl b/staging/security/see/storage/aidl/android/hardware/security/see/storage/ISecureStorage.aidl
index 022de9a..1841bf5 100644
--- a/staging/security/see/storage/aidl/android/hardware/security/see/storage/ISecureStorage.aidl
+++ b/staging/security/see/storage/aidl/android/hardware/security/see/storage/ISecureStorage.aidl
@@ -34,6 +34,13 @@
/**
* Starts a storage session for a filesystem.
*
+ * Clients should be prepared for `startSession` and any methods called on the `IStorageSession`
+ * or its sub-interfaces to return `WOULD_BLOCK` (a `binder::Status` with an exception code of
+ * `EX_TRANSACTION_FAILED` and a transaction error code of `android::WOULD_BLOCK`), which
+ * indicates that the requested storage is not currently available. Possible cases that might
+ * cause this return code might be accessing the data partition during boot stages where it
+ * isn't yet mounted or attempting to commit changes while an A/B update is in progress.
+ *
* @filesystem:
* The minimum filesystem properties requested.
*