From 67f159c5e32d67d5abfa24470f15739a4cf82fd7 Mon Sep 17 00:00:00 2001
From: Abtin Keshavarzian <abtink@google.com>
Date: Tue, 18 Jun 2019 11:48:44 -0700
Subject: [PATCH] [data-poll-manager] remove code handling NO_BUFS error
 (#3918)

This commit remove the logic in `DataPollManager` related to handling
the `NO_BUFS` error case when sending a data poll. This logic is no
longer needed since the data poll tx logic is now handled by `Mac`
layer directly and there is no need to allocate/use a `Message` instance
for data poll (which could lead to `NO_BUFs` error situation).
---
 src/core/thread/data_poll_manager.cpp | 25 ++-----------------------
 src/core/thread/data_poll_manager.hpp | 14 ++++++--------
 2 files changed, 8 insertions(+), 31 deletions(-)

diff --git a/src/core/thread/data_poll_manager.cpp b/src/core/thread/data_poll_manager.cpp
index f407766a4..4b093b80e 100644
--- a/src/core/thread/data_poll_manager.cpp
+++ b/src/core/thread/data_poll_manager.cpp
@@ -56,7 +56,6 @@ DataPollManager::DataPollManager(Instance &aInstance)
     , mEnabled(false)
     , mAttachMode(false)
     , mRetxMode(false)
-    , mNoBufferRetxMode(false)
     , mPollTimeoutCounter(0)
     , mPollTxFailureCounter(0)
     , mRemainingFastPolls(0)
@@ -82,7 +81,6 @@ void DataPollManager::StopPolling(void)
     mTimer.Stop();
     mAttachMode           = false;
     mRetxMode             = false;
-    mNoBufferRetxMode     = false;
     mPollTimeoutCounter   = 0;
     mPollTxFailureCounter = 0;
     mRemainingFastPolls   = 0;
@@ -111,17 +109,7 @@ exit:
     {
     case OT_ERROR_NONE:
         otLogDebgMac("Sending data poll");
-
-        if (mNoBufferRetxMode == true)
-        {
-            mNoBufferRetxMode = false;
-            ScheduleNextPoll(kRecalculatePollPeriod);
-        }
-        else
-        {
-            ScheduleNextPoll(kUsePreviousPollPeriod);
-        }
-
+        ScheduleNextPoll(kUsePreviousPollPeriod);
         break;
 
     case OT_ERROR_INVALID_STATE:
@@ -134,9 +122,8 @@ exit:
         ScheduleNextPoll(kUsePreviousPollPeriod);
         break;
 
-    case OT_ERROR_NO_BUFS:
     default:
-        mNoBufferRetxMode = true;
+        otLogWarnMac("Unexpected error %s requesting data poll", otThreadErrorToString(error));
         ScheduleNextPoll(kRecalculatePollPeriod);
         break;
     }
@@ -440,14 +427,6 @@ uint32_t DataPollManager::CalculatePollPeriod(void) const
         }
     }
 
-    if (mNoBufferRetxMode == true)
-    {
-        if ((period == 0) || (period > kNoBufferRetxPollPeriod))
-        {
-            period = kNoBufferRetxPollPeriod;
-        }
-    }
-
     if (mRemainingFastPolls != 0)
     {
         if ((period == 0) || (period > kFastPollPeriod))
diff --git a/src/core/thread/data_poll_manager.hpp b/src/core/thread/data_poll_manager.hpp
index 4d7745953..6a0646a60 100644
--- a/src/core/thread/data_poll_manager.hpp
+++ b/src/core/thread/data_poll_manager.hpp
@@ -219,13 +219,12 @@ public:
 private:
     enum // Poll period under different conditions (in milliseconds).
     {
-        kAttachDataPollPeriod   = OPENTHREAD_CONFIG_ATTACH_DATA_POLL_PERIOD, ///< Poll period during attach.
-        kRetxPollPeriod         = OPENTHREAD_CONFIG_RETX_POLL_PERIOD,        ///< Poll retx period due to tx failure.
-        kNoBufferRetxPollPeriod = 200,                                       ///< Poll retx due to no buffer space.
-        kFastPollPeriod         = 188,                                       ///< Period used for fast polls.
-        kMinPollPeriod          = OPENTHREAD_CONFIG_MINIMUM_POLL_PERIOD,     ///< Minimum allowed poll period.
-        kMaxExternalPeriod      = ((1 << 26) - 1),                           ///< Maximum allowed user-specified period.
-                                                                             ///< i.e. (0x3FFFFF)ms, about 18.64 hours.
+        kAttachDataPollPeriod = OPENTHREAD_CONFIG_ATTACH_DATA_POLL_PERIOD, ///< Poll period during attach.
+        kRetxPollPeriod       = OPENTHREAD_CONFIG_RETX_POLL_PERIOD,        ///< Poll retx period due to tx failure.
+        kFastPollPeriod       = 188,                                       ///< Period used for fast polls.
+        kMinPollPeriod        = OPENTHREAD_CONFIG_MINIMUM_POLL_PERIOD,     ///< Minimum allowed poll period.
+        kMaxExternalPeriod    = ((1 << 26) - 1),                           ///< Maximum allowed user-specified period.
+                                                                           ///< i.e. (0x3FFFFF)ms, about 18.64 hours.
     };
 
     enum
@@ -256,7 +255,6 @@ private:
     bool    mEnabled : 1;              //< Indicates whether data polling is enabled/started.
     bool    mAttachMode : 1;           //< Indicates whether in attach mode (to use attach poll period).
     bool    mRetxMode : 1;             //< Indicates whether last poll tx failed at mac/radio layer (poll retx mode).
-    bool    mNoBufferRetxMode : 1;     //< Indicates whether last poll tx failed due to insufficient buffer.
     uint8_t mPollTimeoutCounter : 4;   //< Poll timeouts counter (0 to `kQuickPollsAfterTimout`).
     uint8_t mPollTxFailureCounter : 4; //< Poll tx failure counter (0 to `kMaxPollRetxAttempts`).
     uint8_t mRemainingFastPolls : 4;   //< Number of remaining fast polls when in transient fast polling mode.