linux-kernel - Re: [PATCH 03/18] xen/pvcalls: initialize the module and register the xenbus backend

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Message-ID: <alpine.DEB.2.10.1705161321250.4103@sstabellini-ThinkPad-X260>
Date:   Tue, 16 May 2017 13:22:16 -0700 (PDT)
From:   Stefano Stabellini <sstabellini@...nel.org>
To:     Stefano Stabellini <sstabellini@...nel.org>
cc:     Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        xen-devel@...ts.xen.org, linux-kernel@...r.kernel.org,
        jgross@...e.com, Stefano Stabellini <stefano@...reto.com>
Subject: Re: [PATCH 03/18] xen/pvcalls: initialize the module and register
 the xenbus backend

On Tue, 16 May 2017, Stefano Stabellini wrote:
> > And why are you using a rw semaphore --- I only noticed two instances of use
> > and both are writes.
> 
> Yes, this is wrong, legacy from a previous version of the codebase. A
> simple spin_lock should suffice for this use-case.

I replied too quickly: it is best as a semaphore because the functions
within the critical regions can cause a reschedule. But there is no need
to use a rw_semaphore, so I'll switch it to a regular semaphore.