linux-kernel - Re: [PATCH] padata: use smp_mb in padata_reorder to avoid orphaned padata jobs

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Message-ID: <20190716150142.rebjmpjjiesaiwyt@gondor.apana.org.au>
Date:   Tue, 16 Jul 2019 23:01:42 +0800
From:   Herbert Xu <herbert@...dor.apana.org.au>
To:     Andrea Parri <andrea.parri@...rulasolutions.com>
Cc:     Daniel Jordan <daniel.m.jordan@...cle.com>,
        Steffen Klassert <steffen.klassert@...unet.com>,
        boqun.feng@...il.com, paulmck@...ux.ibm.com, peterz@...radead.org,
        linux-arch@...r.kernel.org, linux-crypto@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] padata: use smp_mb in padata_reorder to avoid orphaned
 padata jobs

On Tue, Jul 16, 2019 at 02:53:09PM +0200, Andrea Parri wrote:
>
> P1(atomic_t *reorder_objects, spinlock_t *pd_lock, spinlock_t *reorder_lock)
> {
> 	int r1;
> 
> 	spin_lock(reorder_lock);
> 	atomic_inc(reorder_objects);
> 	spin_unlock(reorder_lock);
> 	//smp_mb();
> 	r1 = spin_trylock(pd_lock);
> }

Yes we need a matching mb on the other side.  However, we can
get away with using smp_mb__after_atomic thanks to the atomic_inc
above.

Daniel, can you please respin the patch with the matching smp_mb?

Thanks,
-- 
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