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Date: Thu, 16 Jul 2020 23:29:53 -0700
From: Hydro Flask <hydroflask@yqxmail.com>
To: Florian Weimer <fweimer@redhat.com>
Cc: musl@lists.openwall.com
In-Reply-To: <87pn8uwu18.fsf@oldenburg2.str.redhat.com>
References: <04c05d65470b5c94808481eaf724cc5d@yqxmail.com>
 <87pn8uwu18.fsf@oldenburg2.str.redhat.com>
Message-ID: <4095a8a7f75becee9bcfc71024e43802@yqxmail.com>
Subject: Re: [musl] Idea: futex() system call entry point

On 2020-07-16 23:10, Florian Weimer wrote:
> * Hydro Flask:
> 
>> I have a project that implements an API that must be AS-safe.
> 
>> Had the idea of using futex() but my other constraint is that the
>> blocking call must also be a cancellation point.
> 
> Cancellation points in signal handlers lead to asynchronous
> cancellation.  Are you sure that this is what you want?

Yes I am aware of that. The caller is responsible for making sure it is 
safe to call the cancellation point in the signal handler per the 
recommendations in POSIX.

This same API is used in both synchronous and asynchronous contexts, 
which is why it must be a cancellation point.