netdev - Re: [PATCH] lib: test_rhashtable: fix for large entry counts

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Message-ID: <20170724031840.GA25786@gondor.apana.org.au>
Date:   Mon, 24 Jul 2017 11:18:41 +0800
From:   Herbert Xu <herbert@...dor.apana.org.au>
To:     Phil Sutter <phil@....cc>
Cc:     Thomas Graf <tgraf@...g.ch>, netdev@...r.kernel.org,
        Manuel Messner <mm@...lett.io>
Subject: Re: [PATCH] lib: test_rhashtable: fix for large entry counts

On Fri, Jul 21, 2017 at 04:51:31PM +0200, Phil Sutter wrote:
> During concurrent access testing, threadfunc() concatenated thread ID
> and object index to create a unique key like so:
> 
> | tdata->objs[i].value = (tdata->id << 16) | i;
> 
> This breaks if a user passes an entries parameter of 64k or higher,
> since 'i' might use more than 16 bits then. Effectively, this will lead
> to duplicate keys in the table.
> 
> Fix the problem by introducing a struct holding object and thread ID and
> using that as key instead of a single integer type field.
> 
> Fixes: f4a3e90ba5739 ("rhashtable-test: extend to test concurrency")
> Reported by: Manuel Messner <mm@...lett.io>
> Signed-off-by: Phil Sutter <phil@....cc>

Acked-by: Herbert Xu <herbert@...dor.apana.org.au>
-- 
Email: Herbert Xu <herbert@...dor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
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