Messages in this thread | | | Date | Fri, 30 Sep 2005 11:04:04 +1000 | Subject | Re: [RFC][PATCH] identify in_dev_get rcu read-side critical sections | From | Herbert Xu <> |
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On Thu, Sep 29, 2005 at 05:36:42PM -0700, Paul E. McKenney wrote: > > > rcu_read_lock(); > > in_dev = dev->ip_ptr; > > if (in_dev) { > > in_dev = rcu_dereference(in_dev); > > atomic_inc(&in_dev->refcnt); > > } > > rcu_read_unlock(); > > return in_dev; > > How about: > > rcu_read_lock(); > in_dev = dev->ip_ptr; > if (rcu_dereference(in_dev)) { > atomic_inc(&in_dev->refcnt); > } > rcu_read_unlock(); > return in_dev;
With this the barrier will taken even when in_dev is NULL.
I agree this isn't such a big deal since it only impacts Alpha and then only when in_dev is NULL. But as we already do the branch anyway to increment the reference count, we might as well make things a little better for Alpha.
Cheers, -- Visit Openswan at http://www.openswan.org/ Email: Herbert Xu ~{PmV>HI~} <herbert@gondor.apana.org.au> Home Page: http://gondor.apana.org.au/~herbert/ PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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