Re: deadlock in waitchld()

[Roman Rakus]

The race is in do-while loop in wait_for(). At the start of wait_for() 
we are blocking SIGCHLD, however echo process ends during the loop and 
we don't register it (don't handle SIGCHLD, which is sent).
Looking at the code, there is MUST_UNBLOCK_CHLD. May it make any harm to 
enable it by default?

RR

On 05/24/2013 02:12 PM, Roman Rakus wrote:
> I have done a bit of debugging and have some results:
> The problem is that waitchld is called even if there aren't any children
> running. The waitchld() is called more then once. I don't know what is
> the logic behind it.
>
> Will check, if there is any child, helps?
>
> RR
>
> On 05/20/2013 04:11 PM, Roman Rakus wrote:
> > Bash hangs in wait4() (WAITPID) if TERM signal trap handler is executed
> > during execution of pipeline.
> >
> > RR
> >
> > Reproducer:
> > #!/bin/bash
> > trap "/bin/echo trapped $$" TERM
> > printf '%d\n' $$
> > while :; do
> >    dd if=/dev/zero bs=1k count=128 2>&1 | cat > /dev/null
> > done
> >
> > and bombard the bash process with TERM signals:
> > #!/bin/bash
> > while :; do
> >    kill -TERM $1 || break
> >    usleep 100000
> > done