linux-kernel - Re: [PATCH] padata: Use RCU when fetching pd from do

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Message-ID: <20190716131807.twahbbdff6jhpnu2@gondor.apana.org.au>
Date:   Tue, 16 Jul 2019 21:18:07 +0800
From:   Herbert Xu <herbert@...dor.apana.org.au>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     Steffen Klassert <steffen.klassert@...unet.com>,
        Daniel Jordan <daniel.m.jordan@...cle.com>,
        andrea.parri@...rulasolutions.com, boqun.feng@...il.com,
        paulmck@...ux.ibm.com, linux-arch@...r.kernel.org,
        linux-crypto@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] padata: Use RCU when fetching pd from do_serial

On Tue, Jul 16, 2019 at 03:15:20PM +0200, Peter Zijlstra wrote:
>
> > @@ -367,7 +368,7 @@ void padata_do_serial(struct padata_priv *padata)
> >  	struct parallel_data *pd;
> >  	int reorder_via_wq = 0;
> >  
> > -	pd = padata->pd;
> > +	pd = rcu_dereference_bh(padata->inst->pd);
> >  
> >  	cpu = get_cpu();
> >  
> 
> That's weird for not having a matching assign and lacking comments to
> explain that.

There is a matching rcu_assign_pointer.  But we should add some
RCU markers.

Or perhaps you're misreading the level of indirections :)

Cheers,
-- 
Email: Herbert Xu <herbert@...dor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt