Guard preferred_dscp with the network interface lock

Bug: webrtc:10389
Change-Id: I96112c2135c9c2d545140feeef6345f8a9b81086
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/126540
Commit-Queue: Steve Anton <steveanton@webrtc.org>
Reviewed-by: Amit Hilbuch <amithi@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#27043}

media/base/media_channel.cc

@@ -35,10 +35,6 @@ int MediaChannel::GetRtpSendTimeExtnId() const {
   return -1;
 }
 
-rtc::DiffServCodePoint MediaChannel::PreferredDscp() const {
-  return rtc::DSCP_DEFAULT;
-}
-
 void MediaChannel::SetFrameEncryptor(
     uint32_t ssrc,
     rtc::scoped_refptr<webrtc::FrameEncryptorInterface> frame_encryptor) {

media/base/media_channel.h

@@ -280,23 +280,37 @@ class MediaChannel : public sigslot::has_slots<> {
       const webrtc::RtpParameters& parameters) = 0;
 
  protected:
-  virtual rtc::DiffServCodePoint PreferredDscp() const;
-
   bool DscpEnabled() const { return enable_dscp_; }
 
-  // This method sets DSCP |value| on both RTP and RTCP channels.
-  int UpdateDscp() {
+  // This is the DSCP value used for both RTP and RTCP channels if DSCP is
+  // enabled. It can be changed at any time via |SetPreferredDscp|.
+  rtc::DiffServCodePoint PreferredDscp() const {
+    rtc::CritScope cs(&network_interface_crit_);
+    return preferred_dscp_;
+  }
+
+  int SetPreferredDscp(rtc::DiffServCodePoint preferred_dscp) {
+    rtc::CritScope cs(&network_interface_crit_);
+    if (preferred_dscp == preferred_dscp_) {
+      return 0;
+    }
+    preferred_dscp_ = preferred_dscp;
+    return UpdateDscp();
+  }
+
+ private:
+  // Apply the preferred DSCP setting to the underlying network interface RTP
+  // and RTCP channels. If DSCP is disabled, then apply the default DSCP value.
+  int UpdateDscp() RTC_EXCLUSIVE_LOCKS_REQUIRED(network_interface_crit_) {
     rtc::DiffServCodePoint value =
-        enable_dscp_ ? PreferredDscp() : rtc::DSCP_DEFAULT;
-    int ret;
-    ret = SetOption(NetworkInterface::ST_RTP, rtc::Socket::OPT_DSCP, value);
+        enable_dscp_ ? preferred_dscp_ : rtc::DSCP_DEFAULT;
+    int ret = SetOption(NetworkInterface::ST_RTP, rtc::Socket::OPT_DSCP, value);
     if (ret == 0) {
       ret = SetOption(NetworkInterface::ST_RTCP, rtc::Socket::OPT_DSCP, value);
     }
     return ret;
   }
 
- private:
   bool DoSendPacket(rtc::CopyOnWriteBuffer* packet,
                     bool rtcp,
                     const rtc::PacketOptions& options) {
@@ -313,7 +327,10 @@ class MediaChannel : public sigslot::has_slots<> {
   // from any MediaEngine threads. This critical section is to protect accessing
   // of network_interface_ object.
   rtc::CriticalSection network_interface_crit_;
-  NetworkInterface* network_interface_ = nullptr;
+  NetworkInterface* network_interface_ RTC_GUARDED_BY(network_interface_crit_) =
+      nullptr;
+  rtc::DiffServCodePoint preferred_dscp_
+      RTC_GUARDED_BY(network_interface_crit_) = rtc::DSCP_DEFAULT;
   webrtc::MediaTransportInterface* media_transport_ = nullptr;
   bool extmap_allow_mixed_ = false;
 };

media/base/rtp_data_engine.cc

@@ -56,6 +56,7 @@ static const DataCodec* FindCodecByName(const std::vector<DataCodec>& codecs,
 RtpDataMediaChannel::RtpDataMediaChannel(const MediaConfig& config)
     : DataMediaChannel(config) {
   Construct();
+  SetPreferredDscp(rtc::DSCP_AF41);
 }
 
 void RtpDataMediaChannel::Construct() {
@@ -331,8 +332,4 @@ bool RtpDataMediaChannel::SendData(const SendDataParams& params,
   return true;
 }
 
-rtc::DiffServCodePoint RtpDataMediaChannel::PreferredDscp() const {
-  return rtc::DSCP_AF41;
-}
-
 }  // namespace cricket

media/base/rtp_data_engine.h

@@ -89,7 +89,6 @@ class RtpDataMediaChannel : public DataMediaChannel {
   virtual bool SendData(const SendDataParams& params,
                         const rtc::CopyOnWriteBuffer& payload,
                         SendDataResult* result);
-  virtual rtc::DiffServCodePoint PreferredDscp() const;
 
  private:
   void Construct();

media/engine/webrtc_video_engine.cc

@@ -524,7 +524,6 @@ WebRtcVideoChannel::WebRtcVideoChannel(
       encoder_factory_(encoder_factory),
       decoder_factory_(decoder_factory),
       bitrate_allocator_factory_(bitrate_allocator_factory),
-      preferred_dscp_(rtc::DSCP_DEFAULT),
       default_send_options_(options),
       last_stats_log_ms_(-1),
       discard_unknown_ssrc_packets_(webrtc::field_trial::IsEnabled(
@@ -660,11 +659,6 @@ bool WebRtcVideoChannel::GetChangedSendParameters(
   return true;
 }
 
-rtc::DiffServCodePoint WebRtcVideoChannel::PreferredDscp() const {
-  RTC_DCHECK_RUN_ON(&thread_checker_);
-  return preferred_dscp_;
-}
-
 bool WebRtcVideoChannel::SetSendParameters(const VideoSendParameters& params) {
   RTC_DCHECK_RUN_ON(&thread_checker_);
   TRACE_EVENT0("webrtc", "WebRtcVideoChannel::SetSendParameters");
@@ -800,10 +794,7 @@ webrtc::RTCError WebRtcVideoChannel::SetRtpSendParameters(
       return webrtc::RTCError(webrtc::RTCErrorType::INVALID_RANGE);
     }
 
-    if (new_dscp != preferred_dscp_) {
-      preferred_dscp_ = new_dscp;
-      MediaChannel::UpdateDscp();
-    }
+    SetPreferredDscp(new_dscp);
   }
 
   return it->second->SetRtpParameters(parameters);

media/engine/webrtc_video_engine.h

@@ -118,8 +118,6 @@ class WebRtcVideoChannel : public VideoMediaChannel, public webrtc::Transport {
   ~WebRtcVideoChannel() override;
 
   // VideoMediaChannel implementation
-  rtc::DiffServCodePoint PreferredDscp() const override;
-
   bool SetSendParameters(const VideoSendParameters& params) override;
   bool SetRecvParameters(const VideoRecvParameters& params) override;
   webrtc::RtpParameters GetRtpSendParameters(uint32_t ssrc) const override;
@@ -529,7 +527,6 @@ class WebRtcVideoChannel : public VideoMediaChannel, public webrtc::Transport {
   // TODO(deadbeef): Don't duplicate information between
   // send_params/recv_params, rtp_extensions, options, etc.
   VideoSendParameters send_params_ RTC_GUARDED_BY(thread_checker_);
-  rtc::DiffServCodePoint preferred_dscp_ RTC_GUARDED_BY(thread_checker_);
   VideoOptions default_send_options_ RTC_GUARDED_BY(thread_checker_);
   VideoRecvParameters recv_params_ RTC_GUARDED_BY(thread_checker_);
   int64_t last_stats_log_ms_ RTC_GUARDED_BY(thread_checker_);

media/engine/webrtc_voice_engine.cc

@@ -1275,10 +1275,6 @@ WebRtcVoiceMediaChannel::~WebRtcVoiceMediaChannel() {
   engine()->UnregisterChannel(this);
 }
 
-rtc::DiffServCodePoint WebRtcVoiceMediaChannel::PreferredDscp() const {
-  return preferred_dscp_;
-}
-
 bool WebRtcVoiceMediaChannel::SetSendParameters(
     const AudioSendParameters& params) {
   TRACE_EVENT0("webrtc", "WebRtcVoiceMediaChannel::SetSendParameters");
@@ -1407,10 +1403,7 @@ webrtc::RTCError WebRtcVoiceMediaChannel::SetRtpSendParameters(
       return webrtc::RTCError(webrtc::RTCErrorType::INVALID_RANGE);
     }
 
-    if (new_dscp != preferred_dscp_) {
-      preferred_dscp_ = new_dscp;
-      MediaChannel::UpdateDscp();
-    }
+    SetPreferredDscp(new_dscp);
   }
 
   // TODO(minyue): The following legacy actions go into

media/engine/webrtc_voice_engine.h

@@ -155,8 +155,6 @@ class WebRtcVoiceMediaChannel final : public VoiceMediaChannel,
 
   const AudioOptions& options() const { return options_; }
 
-  rtc::DiffServCodePoint PreferredDscp() const override;
-
   bool SetSendParameters(const AudioSendParameters& params) override;
   bool SetRecvParameters(const AudioRecvParameters& params) override;
   webrtc::RtpParameters GetRtpSendParameters(uint32_t ssrc) const override;
@@ -275,7 +273,6 @@ class WebRtcVoiceMediaChannel final : public VoiceMediaChannel,
   std::vector<AudioCodec> recv_codecs_;
 
   int max_send_bitrate_bps_ = 0;
-  rtc::DiffServCodePoint preferred_dscp_ = rtc::DSCP_DEFAULT;
   AudioOptions options_;
   absl::optional<int> dtmf_payload_type_;
   int dtmf_payload_freq_ = -1;