Re: [PATCHv4 2/3] grant_table: convert grant table rwlock to percpu rwlock

From: "Jan Beulich" <JBeulich@suse.com>
To: malcolm.crossley@citrix.com
Cc: keir@xen.org, ian.campbell@citrix.com,
	george.dunlap@eu.citrix.com, andrew.cooper3@citrix.com,
	dario.faggioli@citrix.com, Marcos.Matsunaga@oracle.com,
	stefano.stabellini@citrix.com, xen-devel@lists.xenproject.org
Subject: Re: [PATCHv4 2/3] grant_table: convert grant table rwlock to percpu rwlock
Date: Fri, 18 Dec 2015 04:41:03 -0700	[thread overview]
Message-ID: <5673FEDF02000078000C125D@prv-mh.provo.novell.com> (raw)
In-Reply-To: <1450433179-17827-3-git-send-email-malcolm.crossley@citrix.com>

>>> On 18.12.15 at 11:06, <malcolm.crossley@citrix.com> wrote:
> --- a/xen/include/xen/grant_table.h
> +++ b/xen/include/xen/grant_table.h
> @@ -51,13 +51,35 @@
>  /* The maximum size of a grant table. */
>  extern unsigned int max_grant_frames;
>  
> +DECLARE_PERCPU_RWLOCK_GLOBAL(grant_rwlock);
> +
> +static inline void grant_percpu_read_lock(percpu_rwlock_t *lock)
> +{
> +    percpu_read_lock(grant_rwlock, lock);
> +}
> +
> +static inline void grant_percpu_read_unlock(percpu_rwlock_t *lock)
> +{
> +    percpu_read_unlock(grant_rwlock, lock);
> +}
> +
> +static inline void grant_percpu_write_lock(percpu_rwlock_t *lock)
> +{
> +    percpu_write_lock(grant_rwlock, lock);
> +}
> +
> +static inline void grant_percpu_write_unlock(percpu_rwlock_t *lock)
> +{
> +    percpu_write_unlock(grant_rwlock, lock);
> +}

These should all be taking struct grant_table * arguments, so they
can't be accidentally used on some other per-CPU r/w lock. I also
question the need for the "percpu" in their names.

Jan