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Re: LIBC_PROBE and locks
- From: Florian Weimer <fweimer at redhat dot com>
- To: "Carlos O'Donell" <carlos at redhat dot com>
- Cc: GNU C Library <libc-alpha at sourceware dot org>
- Date: Tue, 17 Nov 2015 15:12:12 +0100
- Subject: Re: LIBC_PROBE and locks
- Authentication-results: sourceware.org; auth=none
- References: <564A1849 dot 1040304 at redhat dot com> <564AAB0E dot 8060806 at redhat dot com>
On 11/17/2015 05:20 AM, Carlos O'Donell wrote:
> On 11/16/2015 12:54 PM, Florian Weimer wrote:
>> Is it okay to call LIBC_PROBE while internal locks are held? Or could
>> this result in deadlocks by itself? (I'm aware that the arguments are
>> always evaluated.)
>
> How would it cause deadlocks? The external observer, say systemtap or
> gdb, are outside of the process and should not modify the state of the
> process in such a way as to cause a deadlock. Under what conditions might
> the evaluation of the arguments cause a deadlock?
Are only external observers supported? I wasn't sure if this is some
sort of self-observing capability which is supposed to work, in which
case this would be some sort of callback mechanism and subject to
similar locking issues.
Frank tells me that self-inspection isn't supported, so my concern is
unfounded.
Florian