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Re: [PATCH v2] malloc: Fix list_lock/arena lock deadlock [BZ #19182]
- From: "Carlos O'Donell" <carlos at redhat dot com>
- To: Florian Weimer <fweimer at redhat dot com>, Torvald Riegel <triegel at redhat dot com>
- Cc: GNU C Library <libc-alpha at sourceware dot org>
- Date: Tue, 22 Dec 2015 15:16:18 -0500
- Subject: Re: [PATCH v2] malloc: Fix list_lock/arena lock deadlock [BZ #19182]
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On 12/22/2015 02:32 PM, Florian Weimer wrote:
> On 12/21/2015 10:54 PM, Carlos O'Donell wrote:
>
>>> + list_lock also prevents concurrent forks. When list_lock is
>>> + acquired, no arena lock must be acquired, but it is permitted to
>>> + acquire arena locks after list_lock. */
>>
>> This last sentence seems ambiguous to me. I assume you mean to say that
>> at the point at which list_lock is acquired there are no other arena
>> locks held, but that after list_lock is acquired, other arena locks may
>> be acquired afterwards?
>
> That was my intent. Is this clearer?
>
> list_lock also prevents concurrent forks. At the time list_lock is
> acquired, no arena lock must have been acquired, but it is permitted
> to acquire arena locks subsequently, while list_lock is acquired.
>
> I'm following Torvald's earlier guidance not to speak of âheldâ locks.
Looks good to me.
Cheers,
Carlos.