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Date: Mon, 02 May 2022 22:54:25 +0300
From: Alexey Izbyshev <izbyshev@ispras.ru>
To: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Cc: Florian Weimer <fweimer@redhat.com>, libc-alpha@sourceware.org
Subject: Re: [PATCH] linux: Fallback to fork and exec for clone fail on
 posix_spawn (BZ#29115)
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On 2022-05-02 22:42, Adhemerval Zanella wrote:
> On 02/05/2022 16:15, Alexey Izbyshev wrote:
>> On 2022-05-02 21:06, Adhemerval Zanella wrote:
>>> +      while (__write_nocancel (args->pipe[1], &ret, sizeof (ret)) < 
>>> 0);
>> 
>> If the parent is killed, write() will fail with EPIPE, so this loop 
>> will become infinite. Maybe check for EPIPE and break?
> 
> We block all signals (__libc_signal_block_all), so the parent will be
> only killed
> by signals that can no be caught (SIGKILL).  Same for SIGPIPE.

The parent can indeed only be killed by SIGKILL, or simply exit from 
another thread, but how exactly it dies doesn't matter. But signals are 
already unblocked at this point in the child, so if SIGPIPE was ignored 
in the parent, it's ignored now in the child and is unblocked, hence 
write() can fail with EPIPE.

Alexey