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

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Message-ID: <c1bbbe94-dbdc-da14-e0c3-850c965d8b5d@oracle.com>
Date:   Tue, 16 Jul 2019 11:44:12 -0400
From:   Daniel Jordan <daniel.m.jordan@...cle.com>
To:     Herbert Xu <herbert@...dor.apana.org.au>,
        Andrea Parri <andrea.parri@...rulasolutions.com>
Cc:     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 7/16/19 11:01 AM, Herbert Xu wrote:
> 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?

Sure, Herbert, will do.

Thanks,
Daniel