From: Andreas Sandberg <andreas@sandberg.pp.se>
Date: Mon, 7 Oct 2013 14:03:15 +0000 (+0200)
Subject: base: Fix a potential race in PollQueue::setupAsyncIO
X-Git-Tag: stable_2014_02_15~98
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=c0f367e51454dc9d2610bbd3266a80cec7b4ad69;p=gem5.git

base: Fix a potential race in PollQueue::setupAsyncIO

There is a potential race between enabling asynchronous IO and
selecting the target for the SIGIO signal. This changeset move the
F_SETOWN call to before the F_SETFL call that enables SIGIO
delivery. This ensures that signals are always sent to the correct
process.
---

diff --git a/src/base/pollevent.cc b/src/base/pollevent.cc
index 67708c129..cb44d8728 100644
--- a/src/base/pollevent.cc
+++ b/src/base/pollevent.cc
@@ -213,13 +213,13 @@ PollQueue::setupAsyncIO(int fd, bool set)
     else
         flags &= ~(FASYNC);
 
-    if (fcntl(fd, F_SETFL, flags) == -1)
-        panic("Could not set up async IO");
-
     if (set) {
       if (fcntl(fd, F_SETOWN, getpid()) == -1)
         panic("Could not set up async IO");
     }
+
+    if (fcntl(fd, F_SETFL, flags) == -1)
+        panic("Could not set up async IO");
 }
 
 void