diff --git a/app/controllers/projects/commit_controller.rb b/app/controllers/projects/commit_controller.rb
index 35df421e09d..78d42d695b6 100644
--- a/app/controllers/projects/commit_controller.rb
+++ b/app/controllers/projects/commit_controller.rb
@@ -10,11 +10,11 @@ class Projects::CommitController < Projects::ApplicationController
   def show
     return git_not_found! unless @commit
 
-    @line_notes = commit.notes(@project).inline
+    @line_notes = commit.notes.inline
     @diffs = @commit.diffs
     @note = @project.build_commit_note(commit)
-    @notes_count = commit.notes(@project).count
-    @notes = commit.notes(@project).not_inline.fresh
+    @notes_count = commit.notes.count
+    @notes = commit.notes.not_inline.fresh
     @noteable = @commit
     @comments_allowed = @reply_allowed = true
     @comments_target  = {
diff --git a/app/models/commit.rb b/app/models/commit.rb
index d4e9ebacac6..1985793c600 100644
--- a/app/models/commit.rb
+++ b/app/models/commit.rb
@@ -103,7 +103,7 @@ class Commit
     description.present?
   end
 
-  def hook_attrs(project)
+  def hook_attrs
     path_with_namespace = project.path_with_namespace
 
     {
@@ -120,7 +120,7 @@ class Commit
 
   # Discover issues should be closed when this commit is pushed to a project's
   # default branch.
-  def closes_issues(project, current_user = self.committer)
+  def closes_issues(current_user = self.committer)
     Gitlab::ClosingIssueExtractor.new(project, current_user).closed_by_message(safe_message)
   end
 
@@ -137,22 +137,22 @@ class Commit
     User.find_for_commit(committer_email, committer_name)
   end
 
-  def participants(project, current_user = nil)
+  def participants(current_user = nil)
     users = []
     users << author
     users << committer
     
-    users.push *self.mentioned_users(current_user, project)
+    users.push *self.mentioned_users(current_user)
 
-    notes(project).each do |note|
+    notes.each do |note|
       users << note.author
-      users.push *note.mentioned_users(current_user, project)
+      users.push *note.mentioned_users(current_user)
     end
 
     users.uniq
   end
 
-  def notes(project)
+  def notes
     project.notes.for_commit_id(self.id)
   end
 
diff --git a/app/models/merge_request.rb b/app/models/merge_request.rb
index 9c9e2762507..e242cae8ea1 100644
--- a/app/models/merge_request.rb
+++ b/app/models/merge_request.rb
@@ -242,7 +242,7 @@ class MergeRequest < ActiveRecord::Base
     }
 
     unless last_commit.nil?
-      attrs.merge!(last_commit: last_commit.hook_attrs(source_project))
+      attrs.merge!(last_commit: last_commit.hook_attrs)
     end
 
     attributes.merge!(attrs)
@@ -259,7 +259,7 @@ class MergeRequest < ActiveRecord::Base
   # Return the set of issues that will be closed if this merge request is accepted.
   def closes_issues(current_user = self.author)
     if target_branch == project.default_branch
-      issues = commits.flat_map { |c| c.closes_issues(project, current_user) }
+      issues = commits.flat_map { |c| c.closes_issues(current_user) }
       issues.push(*Gitlab::ClosingIssueExtractor.new(project, current_user).
                   closed_by_message(description))
       issues.uniq.sort_by(&:id)
diff --git a/app/services/git_push_service.rb b/app/services/git_push_service.rb
index 31e0167d247..3affd6d6463 100644
--- a/app/services/git_push_service.rb
+++ b/app/services/git_push_service.rb
@@ -70,7 +70,7 @@ class GitPushService
       # Close issues if these commits were pushed to the project's default branch and the commit message matches the
       # closing regex. Exclude any mentioned Issues from cross-referencing even if the commits are being pushed to
       # a different branch.
-      issues_to_close = commit.closes_issues(project, user)
+      issues_to_close = commit.closes_issues(user)
 
       # Load commit author only if needed.
       # For push with 1k commits it prevents 900+ requests in database
diff --git a/app/services/notification_service.rb b/app/services/notification_service.rb
index c7e45a2c2c7..0d7ffbeebd9 100644
--- a/app/services/notification_service.rb
+++ b/app/services/notification_service.rb
@@ -129,9 +129,7 @@ class NotificationService
 
     # Add all users participating in the thread (author, assignee, comment authors)
     participants = 
-      if target.is_a?(Commit)
-        target.participants(note.project, note.author)
-      elsif target.respond_to?(:participants)
+      if target.respond_to?(:participants)
         target.participants(note.author)
       else
         note.mentioned_users
diff --git a/app/services/projects/participants_service.rb b/app/services/projects/participants_service.rb
index 05106fa7898..b91590a1a90 100644
--- a/app/services/projects/participants_service.rb
+++ b/app/services/projects/participants_service.rb
@@ -13,21 +13,19 @@ module Projects
     end
 
     def participants_in(type, id)
-      users = 
+      target = 
         case type
         when "Issue"
-          issue = project.issues.find_by_iid(id)
-          issue.participants(current_user) if issue
+          project.issues.find_by_iid(id)
         when "MergeRequest"
-          merge_request = project.merge_requests.find_by_iid(id)
-          merge_request.participants(current_user) if merge_request
+          project.merge_requests.find_by_iid(id)
         when "Commit"
-          commit = project.commit(id)
-          commit.participants(project, current_user) if commit
+          project.commit(id)
         end
+        
+      return [] unless target
 
-      return [] unless users
-      
+      users = target.participants(current_user)
       sorted(users)
     end
 
diff --git a/app/views/projects/commits/_commit.html.haml b/app/views/projects/commits/_commit.html.haml
index 8e1aaa4d051..083fca9b658 100644
--- a/app/views/projects/commits/_commit.html.haml
+++ b/app/views/projects/commits/_commit.html.haml
@@ -12,7 +12,7 @@
       - if @note_counts
         - note_count = @note_counts.fetch(commit.id, 0)
       - else
-        - notes = commit.notes(project)
+        - notes = commit.notes
         - note_count = notes.user.count
 
       - if note_count > 0
diff --git a/lib/gitlab/note_data_builder.rb b/lib/gitlab/note_data_builder.rb
index 0f2abd1b49c..ea6b0ee796d 100644
--- a/lib/gitlab/note_data_builder.rb
+++ b/lib/gitlab/note_data_builder.rb
@@ -70,7 +70,7 @@ module Gitlab
       def build_data_for_commit(project, user, note)
         # commit_id is the SHA hash
         commit = project.commit(note.commit_id)
-        commit.hook_attrs(project)
+        commit.hook_attrs
       end
     end
   end
diff --git a/lib/gitlab/push_data_builder.rb b/lib/gitlab/push_data_builder.rb
index f8da452e4c0..f44eb872122 100644
--- a/lib/gitlab/push_data_builder.rb
+++ b/lib/gitlab/push_data_builder.rb
@@ -30,8 +30,7 @@ module Gitlab
         
         # For performance purposes maximum 20 latest commits
         # will be passed as post receive hook data.
-        commit_attrs = commits_limited.map do |commit|
-          commit.hook_attrs(project)
+        commit_attrs = commits_limited.map(&:hook_attrs)
         end
 
         type = Gitlab::Git.tag_ref?(ref) ? "tag_push" : "push"
diff --git a/spec/models/commit_spec.rb b/spec/models/commit_spec.rb
index 9c37c036eae..ad2ac143d97 100644
--- a/spec/models/commit_spec.rb
+++ b/spec/models/commit_spec.rb
@@ -58,13 +58,13 @@ eos
 
     it 'detects issues that this commit is marked as closing' do
       commit.stub(safe_message: "Fixes ##{issue.iid}")
-      expect(commit.closes_issues(project)).to eq([issue])
+      expect(commit.closes_issues).to eq([issue])
     end
 
     it 'does not detect issues from other projects' do
       ext_ref = "#{other_project.path_with_namespace}##{other_issue.iid}"
       commit.stub(safe_message: "Fixes #{ext_ref}")
-      expect(commit.closes_issues(project)).to be_empty
+      expect(commit.closes_issues).to be_empty
     end
   end