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Subject: Re: [PATCH 2/2] xen: xenbus: WARN_ON XS_TRANSACTION_{START,END}
 misuse
To:     Boris Ostrovsky <boris.ostrovsky@oracle.com>,
        xen-devel@lists.xenproject.org
Cc:     Juergen Gross <jgross@suse.com>, linux-kernel@vger.kernel.org
References: <20180207222236.7434-1-simon@invisiblethingslab.com>
 <20180207222236.7434-2-simon@invisiblethingslab.com>
 <8a0fd059-7acf-3279-10f9-649c19522e2a@oracle.com>
From:   Simon Gaiser <simon@invisiblethingslab.com>
Message-ID: <66103cca-321e-6950-2083-6f5d068e12e6@invisiblethingslab.com>
Date:   Sun, 11 Feb 2018 01:27:00 +0000
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From: Simon Gaiser <simon@invisiblethingslab.com>
To: Boris Ostrovsky <boris.ostrovsky@oracle.com>,
 xen-devel@lists.xenproject.org
Cc: Juergen Gross <jgross@suse.com>, linux-kernel@vger.kernel.org
Message-ID: <66103cca-321e-6950-2083-6f5d068e12e6@invisiblethingslab.com>
Subject: Re: [PATCH 2/2] xen: xenbus: WARN_ON XS_TRANSACTION_{START,END}
 misuse
References: <20180207222236.7434-1-simon@invisiblethingslab.com>
 <20180207222236.7434-2-simon@invisiblethingslab.com>
 <8a0fd059-7acf-3279-10f9-649c19522e2a@oracle.com>
In-Reply-To: <8a0fd059-7acf-3279-10f9-649c19522e2a@oracle.com>

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Boris Ostrovsky:
> On 02/07/2018 05:22 PM, Simon Gaiser wrote:
>> +    users_old =3D xs_state_users;
>>       xs_state_users--;
>>       if ((req->type =3D=3D XS_TRANSACTION_START && req->msg.type =3D=3D=
 XS_ERROR) ||
>>           req->type =3D=3D XS_TRANSACTION_END)
>>           xs_state_users--;
>> +    if (WARN_ON(xs_state_users > users_old))
>=20
>=20
> WARN_ON_ONCE()?

Since we "fix" the wrong decrement by clamping at zero it should not
happen immediately again. But if you prefer _ONCE I can change it.


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