[spinel] improve RCP crash dump request logic (openthread#13150)

This commit updates the RCP crash dump request logic to provide better
debug information while ensuring the recovery process is not interrupted:
- `RadioSpinel::HandleRcpUnexpectedReset` now explicitly clears
  `mWaitingTid` and requests a crash dump if RCP restoration is disabled
  before proceeding with the abort / exit logic. If RCP restoration is
  enabled, request for crash dump will be deferred to `RecoverFromRcpFailure`,
  before resetting the coprocessor.
- Updates crash dump requests to use `IgnoreReturnValue` instead.
  Failing to retrieve a crash dump is not a fatal error and should not
  halt the initialization or recovery process.

Author: wtongze

src/lib/spinel/radio_spinel.cpp

@@ -157,7 +157,7 @@ void RadioSpinel::Init(bool          aSkipRcpVersionCheck,
     if (sSupportsLogCrashDump)
     {
         LogDebg("RCP supports crash dump logging. Requesting crash dump.");
-        SuccessOrExit(error = Set(SPINEL_PROP_RCP_LOG_CRASH_DUMP, nullptr));
+        IgnoreReturnValue(Set(SPINEL_PROP_RCP_LOG_CRASH_DUMP, nullptr));
     }
 
     if (!aSkipRcpVersionCheck)
@@ -1328,14 +1328,17 @@ otError RadioSpinel::Set(spinel_prop_key_t aKey, const char *aFormat, ...)
 #if OPENTHREAD_SPINEL_CONFIG_RCP_RESTORATION_MAX_COUNT > 0
     do
     {
-        RecoverFromRcpFailure();
+        if (aKey != SPINEL_PROP_RCP_LOG_CRASH_DUMP)
+        {
+            RecoverFromRcpFailure();
+        }
 #endif
         va_start(mPropertyArgs, aFormat);
         error = RequestWithExpectedCommandV(SPINEL_CMD_PROP_VALUE_IS, SPINEL_CMD_PROP_VALUE_SET, aKey, aFormat,
                                             mPropertyArgs);
         va_end(mPropertyArgs);
 #if OPENTHREAD_SPINEL_CONFIG_RCP_RESTORATION_MAX_COUNT > 0
-    } while (mRcpFailure != kRcpFailureNone);
+    } while (aKey != SPINEL_PROP_RCP_LOG_CRASH_DUMP && mRcpFailure != kRcpFailureNone);
 #endif
 
     return error;
@@ -1399,19 +1402,31 @@ otError RadioSpinel::WaitResponse(bool aHandleRcpTimeout)
         if ((end <= now) || (GetSpinelDriver().GetSpinelInterface()->WaitForFrame(end - now) != OT_ERROR_NONE))
         {
             LogWarn("Wait for response timeout");
-            if (aHandleRcpTimeout)
+            // Skip RCP timeout handling for the non-essential crash dump property
+            if (aHandleRcpTimeout && mWaitingKey != SPINEL_PROP_RCP_LOG_CRASH_DUMP)
             {
                 HandleRcpTimeout();
             }
             ExitNow(mError = OT_ERROR_RESPONSE_TIMEOUT);
         }
+#if OPENTHREAD_SPINEL_CONFIG_RCP_RESTORATION_MAX_COUNT > 0
+        if (mRcpFailure != kRcpFailureNone)
+        {
+            ExitNow(mError = OT_ERROR_RESPONSE_TIMEOUT);
+        }
+#endif
     } while (mWaitingTid);
 
     LogIfFail("Error waiting response", mError);
     // This indicates end of waiting response.
     mWaitingKey = SPINEL_PROP_LAST_STATUS;
 
 exit:
+    if (mError != OT_ERROR_NONE && mWaitingTid != 0)
+    {
+        FreeTid(mWaitingTid);
+        mWaitingTid = 0;
+    }
     return mError;
 }
 
@@ -1991,11 +2006,20 @@ void RadioSpinel::HandleRcpUnexpectedReset(spinel_status_t aStatus)
 
 #if OPENTHREAD_SPINEL_CONFIG_RCP_RESTORATION_MAX_COUNT > 0
     mRcpFailure = kRcpFailureUnexpectedReset;
-#elif OPENTHREAD_SPINEL_CONFIG_ABORT_ON_UNEXPECTED_RCP_RESET_ENABLE
+#else
+    if (sSupportsLogCrashDump)
+    {
+        mWaitingTid = 0;
+        LogDebg("RCP supports crash dump logging. Requesting crash dump.");
+        IgnoreReturnValue(Set(SPINEL_PROP_RCP_LOG_CRASH_DUMP, nullptr));
+    }
+
+#if OPENTHREAD_SPINEL_CONFIG_ABORT_ON_UNEXPECTED_RCP_RESET_ENABLE
     abort();
 #else
     DieNow(OT_EXIT_RADIO_SPINEL_RESET);
 #endif
+#endif
 }
 
 void RadioSpinel::HandleRcpTimeout(void)
@@ -2044,6 +2068,14 @@ void RadioSpinel::RecoverFromRcpFailure(void)
         DieNow(OT_EXIT_FAILURE);
     }
 
+    if (sSupportsLogCrashDump)
+    {
+        mWaitingTid = 0;
+        LogDebg("RCP supports crash dump logging. Requesting crash dump.");
+        IgnoreReturnValue(Set(SPINEL_PROP_RCP_LOG_CRASH_DUMP, nullptr));
+        mRcpFailure = kRcpFailureNone;
+    }
+
     LogWarn("Trying to recover (%d/%d)", mRcpFailureCount, kMaxFailureCount);
 
     mState = kStateDisabled;
@@ -2106,12 +2138,6 @@ void RadioSpinel::RecoverFromRcpFailure(void)
 
     --mRcpFailureCount;
 
-    if (sSupportsLogCrashDump)
-    {
-        LogDebg("RCP supports crash dump logging. Requesting crash dump.");
-        SuccessOrDie(Set(SPINEL_PROP_RCP_LOG_CRASH_DUMP, nullptr));
-    }
-
     LogNote("RCP recovery is done");
 
 exit: