sys/mount_linux: use pipe for communicating mount result #4160
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Codecov Report
@@ Coverage Diff @@
## master #4160 +/- ##
==========================================
+ Coverage 42.44% 45.70% +3.26%
==========================================
Files 133 119 -14
Lines 15210 12212 -2998
==========================================
- Hits 6456 5582 -874
+ Misses 7821 5698 -2123
+ Partials 933 932 -1
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@AkihiroSuda Since the race condition related issue is only reproduced by introducing some delay within the FMountat function, I'm not sure how this particular scenario can be easily tested. Suggestions are welcome. |
fuweid
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Apr 8, 2020
forkAndMountat forks a process to chdir then mount layers. Signals are blocked (using runtime_beforeFork) during fork. There is a race condition that the child process finishes before the parent process is scheduled and can unblock signal handling. The SIGCHLD signal sent from the finished process may have been delivered to the shim process's reaper thread and caused the parent process fail with ECHLD error. This patch sets up a pipe for communication between child and parent instead of waiting for child exit status. Fixes containerd#4009. Signed-off-by: Haitao Li <hli@atlassian.com>
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forkAndMountat forks a process to chdir then mount layers. Signals are
blocked (using runtime_beforeFork) during fork.
There is a race condition that the child process finishes before the
parent process is scheduled and can unblock signal handling. The SIGCHLD
signal sent from the finished process may have been delivered to the
shim process's reaper thread and caused the parent process fail with
ECHLD error.
This patch sets up a pipe for communication between child and parent
instead of waiting for child exit status.
Fixes #4009.