Date: Thu, 13 Feb 2014 12:59:10 -0800 From: Vijay Singh <vijju.singh@gmail.com> To: Alfred Perlstein <bright@mu.org> Cc: hackers@freebsd.org Subject: Re: Debugging rw lock Message-ID: <CALCNsJQzeqGh%2BZ0rW2jw9e%2BDfKdaRo9BpOQq7XrjfZ1EzNDFYQ@mail.gmail.com> In-Reply-To: <52FD30D9.6050604@mu.org> References: <CALCNsJS6vFJU18F3VRR-T2RdtGNxd3fycUCkQ63BmGp29DAUMw@mail.gmail.com> <52FD30D9.6050604@mu.org>
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You're talking about instrumenting the code, right? But which thread? I was
thinking of augmenting the rw lock to record the readers, but wanted to
check if something is possible without instrumentation.
On Thu, Feb 13, 2014 at 12:53 PM, Alfred Perlstein <bright@mu.org> wrote:
> Keep a stack of rwlocks owned in the struct thread.
>
> -Alfred
>
> On 2/13/14, 12:51 PM, Vijay Singh wrote:
>
>> I am running into an issue where an rw lock is read locked and never
>> unlocked, and causes a system to livelock. I was wondering if its possible
>> to figure out which thread owns the read lock?
>>
>> It's the tcp pcbinfo lock.
>>
>> (kgdb-amd64-7.4-08) show_rwlock rw
>> name : tcp
>> class: rw
>> flags: {SLEEP, INITED, WITNESS, RECURSE, UPGRADABLE}
>> state: RLOCK: 1 locks
>> waiters: writers
>>
>> Any help is appreciated.
>>
>> -vijay
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>>
>>
>
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