[bug #51237] Deadlock in Ctrl-C handler on Windows

[Michael Builov]

URL:
  <http://savannah.gnu.org/bugs/?51237>

                 Summary: Deadlock in Ctrl-C handler on Windows
                 Project: make
            Submitted by: mbuilov
            Submitted on: Wed 14 Jun 2017 12:43:28 PM UTC
                Severity: 3 - Normal
              Item Group: Bug
                  Status: None
                 Privacy: Public
             Assigned to: None
             Open/Closed: Open
         Discussion Lock: Any
       Component Version: 4.2.1
        Operating System: MS Windows
           Fixed Release: None
           Triage Status: None

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Details:

Hello.

There is a bug in processing of Ctrl+C event under WINDOWS.

Gnu make handles Ctrl+C in fatal_error_signal() function, which suspends Main
thread.

But, if Main thread get suspended while it locks resources, where is a
possibility for dead-lock.

It's easy to reproduce dead-lock with this makefile:

# run make -j -O, then press Ctrl+C
all: a b c d
CMD := cmd.exe /c "echo off & for /l %a in (0,1,1000) do echo %a"
a:;$(CMD)
b:;$(CMD)
c:;$(CMD)
d:;$(CMD)
.PHONY: all a b c d

(backtrace1 attached)


Even without job-server and output synchronization, it is possible to
dead-lock make or put it to infinite loop:

# just run make without options, then press Ctrl+C
# (hard to reproduce dead-lock)
GOALS := a b c d e f g h i j k l m n o p q r s t u v w x y z
GOALS += $(GOALS:=1)
GOALS += $(GOALS:=2)
GOALS += $(GOALS:=3)
all: $(GOALS)
$(GOALS):;cmd.exe /c "echo off & echo 1 > NUL"
.PHONY: all $(GOALS)

(backtrace2 attached)


One of possible solutions to this dead-lock problem - instead of suspending
Main thread, Ctrl+C handler thread may notify Main thread to stop and wait
until it releases resources and goes to sleep.

Here is the patch:

https://github.com/mbuilov/gnumake-windows/blob/master/make-4.2.1-win32-ctrl-c.patch




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File Attachments:


-------------------------------------------------------
Date: Wed 14 Jun 2017 12:43:28 PM UTC  Name: backtrace1  Size: 1kB   By:
mbuilov
backtraces of dead-locked Main and Ctrl+C threads
<http://savannah.gnu.org/bugs/download.php?file_id=40917>
-------------------------------------------------------
Date: Wed 14 Jun 2017 12:43:28 PM UTC  Name: backtrace2  Size: 2kB   By:
mbuilov
backtraces of dead-locked Main and Ctrl+C threads
<http://savannah.gnu.org/bugs/download.php?file_id=40918>

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