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Tsirkin" Cc: linux-kernel@vger.kernel.org, Greg Kroah-Hartman , Amit Shah , virtualization@lists.linux-foundation.org, Arnd Bergmann References: <20191018164718.15999-1-lvivier@redhat.com> <20191106085548-mutt-send-email-mst@kernel.org> <83d88904-1626-8dd6-9e5c-7abcee27bcd0@redhat.com> <20191106095707-mutt-send-email-mst@kernel.org> From: Laurent Vivier Autocrypt: addr=lvivier@redhat.com; prefer-encrypt=mutual; keydata= mQINBFYFJhkBEAC2me7w2+RizYOKZM+vZCx69GTewOwqzHrrHSG07MUAxJ6AY29/+HYf6EY2 WoeuLWDmXE7A3oJoIsRecD6BXHTb0OYS20lS608anr3B0xn5g0BX7es9Mw+hV/pL+63EOCVm SUVTEQwbGQN62guOKnJJJfphbbv82glIC/Ei4Ky8BwZkUuXd7d5NFJKC9/GDrbWdj75cDNQx UZ9XXbXEKY9MHX83Uy7JFoiFDMOVHn55HnncflUncO0zDzY7CxFeQFwYRbsCXOUL9yBtqLer Ky8/yjBskIlNrp0uQSt9LMoMsdSjYLYhvk1StsNPg74+s4u0Q6z45+l8RAsgLw5OLtTa+ePM JyS7OIGNYxAX6eZk1+91a6tnqfyPcMbduxyBaYXn94HUG162BeuyBkbNoIDkB7pCByed1A7q q9/FbuTDwgVGVLYthYSfTtN0Y60OgNkWCMtFwKxRaXt1WFA5ceqinN/XkgA+vf2Ch72zBkJL RBIhfOPFv5f2Hkkj0MvsUXpOWaOjatiu0fpPo6Hw14UEpywke1zN4NKubApQOlNKZZC4hu6/ 8pv2t4HRi7s0K88jQYBRPObjrN5+owtI51xMaYzvPitHQ2053LmgsOdN9EKOqZeHAYG2SmRW LOxYWKX14YkZI5j/TXfKlTpwSMvXho+efN4kgFvFmP6WT+tPnwARAQABtCNMYXVyZW50IFZp dmllciA8bHZpdmllckByZWRoYXQuY29tPokCOAQTAQIAIgUCVgVQgAIbAwYLCQgHAwIGFQgC CQoLBBYCAwECHgECF4AACgkQ8ww4vT8vvjwpgg//fSGy0Rs/t8cPFuzoY1cex4limJQfReLr SJXCANg9NOWy/bFK5wunj+h/RCFxIFhZcyXveurkBwYikDPUrBoBRoOJY/BHK0iZo7/WQkur 6H5losVZtrotmKOGnP/lJYZ3H6OWvXzdz8LL5hb3TvGOP68K8Bn8UsIaZJoeiKhaNR0sOJyI YYbgFQPWMHfVwHD/U+/gqRhD7apVysxv5by/pKDln1I5v0cRRH6hd8M8oXgKhF2+rAOL7gvh jEHSSWKUlMjC7YwwjSZmUkL+TQyE18e2XBk85X8Da3FznrLiHZFHQ/NzETYxRjnOzD7/kOVy gKD/o7asyWQVU65mh/ECrtjfhtCBSYmIIVkopoLaVJ/kEbVJQegT2P6NgERC/31kmTF69vn8 uQyW11Hk8tyubicByL3/XVBrq4jZdJW3cePNJbTNaT0d/bjMg5zCWHbMErUib2Nellnbg6bc 2HLDe0NLVPuRZhHUHM9hO/JNnHfvgiRQDh6loNOUnm9Iw2YiVgZNnT4soUehMZ7au8PwSl4I KYE4ulJ8RRiydN7fES3IZWmOPlyskp1QMQBD/w16o+lEtY6HSFEzsK3o0vuBRBVp2WKnssVH qeeV01ZHw0bvWKjxVNOksP98eJfWLfV9l9e7s6TaAeySKRRubtJ+21PRuYAxKsaueBfUE7ZT 7ze0LUxhdXJlbnQgVml2aWVyIChSZWQgSGF0KSA8bHZpdmllckByZWRoYXQuY29tPokCOAQT AQIAIgUCVgUmGQIbAwYLCQgHAwIGFQgCCQoLBBYCAwECHgECF4AACgkQ8ww4vT8vvjxtNBAA o2xGmbXl9vJQALkj7MVlsMlgewQ1rdoZl+bZ6ythTSBsqwwtl1BUTQGA1GF2LAchRVYca5bJ lw4ai5OdZ/rc5dco2XgrRFtj1np703BzNEhGU1EFxtms/Y9YOobq/GZpck5rK8jV4osEb8oc 3xEgCm/xFwI/2DOe0/s2cHKzRkvdmKWEDhT1M+7UhtSCnloX776zCsrofYiHP2kasFyMa/5R 9J1Rt9Ax/jEAX5vFJ8+NPf68497nBfrAtLM3Xp03YJSr/LDxer44Mevhz8dFw7IMRLhnuSfr 8jP93lr6Wa8zOe3pGmFXZWpNdkV/L0HaeKwTyDKKdUDH4U7SBnE1gcDfe9x08G+oDfVhqED8 qStKCxPYxRUKIdUjGPF3f5oj7N56Q5zZaZkfxeLNTQ13LDt3wGbVHyZxzFc81B+qT8mkm74y RbeVSuviPTYjbBQ66GsUgiZZpDUyJ6s54fWqQdJf4VFwd7M/mS8WEejbSjglGHMxMGiBeRik Y0+ur5KAF7z0D1KfW1kHO9ImQ0FbEbMbTMf9u2+QOCrSWOz/rj23EwPrCQ2TSRI2fWakMJZ+ zQZvy+ei3D7lZ09I9BT/GfFkTIONgtNfDxwyMc4v4XyP0IvvZs/YZqt7j3atyTZM0S2HSaZ9 rXmQYkBt1/u691cZfvy+Tr2xZaDpFcjPkci5Ag0EVgUmGQEQALxSQRbl/QOnmssVDxWhHM5T Gxl7oLNJms2zmBpcmlrIsn8nNz0rRyxT460k2niaTwowSRK8KWVDeAW6ZAaWiYjLlTunoKwv F8vP3JyWpBz0diTxL5o+xpvy/Q6YU3BNefdq8Vy3rFsxgW7mMSrI/CxJ667y8ot5DVugeS2N yHfmZlPGE0Nsy7hlebS4liisXOrN3jFzasKyUws3VXek4V65lHwB23BVzsnFMn/bw/rPliqX Gcwl8CoJu8dSyrCcd1Ibs0/Inq9S9+t0VmWiQWfQkz4rvEeTQkp/VfgZ6z98JRW7S6l6eoph oWs0/ZyRfOm+QVSqRfFZdxdP2PlGeIFMC3fXJgygXJkFPyWkVElr76JTbtSHsGWbt6xUlYHK XWo+xf9WgtLeby3cfSkEchACrxDrQpj+Jt/JFP+q997dybkyZ5IoHWuPkn7uZGBrKIHmBunT co1+cKSuRiSCYpBIXZMHCzPgVDjk4viPbrV9NwRkmaOxVvye0vctJeWvJ6KA7NoAURplIGCq kCRwg0MmLrfoZnK/gRqVJ/f6adhU1oo6z4p2/z3PemA0C0ANatgHgBb90cd16AUxpdEQmOCm dNnNJF/3Zt3inzF+NFzHoM5Vwq6rc1JPjfC3oqRLJzqAEHBDjQFlqNR3IFCIAo4SYQRBdAHB CzkM4rWyRhuVABEBAAGJAh8EGAECAAkFAlYFJhkCGwwACgkQ8ww4vT8vvjwg9w//VQrcnVg3 TsjEybxDEUBm8dBmnKqcnTBFmxN5FFtIWlEuY8+YMiWRykd8Ln9RJ/98/ghABHz9TN8TRo2b 6WimV64FmlVn17Ri6FgFU3xNt9TTEChqAcNg88eYryKsYpFwegGpwUlaUaaGh1m9OrTzcQy+ klVfZWaVJ9Nw0keoGRGb8j4XjVpL8+2xOhXKrM1fzzb8JtAuSbuzZSQPDwQEI5CKKxp7zf76 J21YeRrEW4WDznPyVcDTa+tz++q2S/BpP4W98bXCBIuQgs2m+OflERv5c3Ojldp04/S4NEjX EYRWdiCxN7ca5iPml5gLtuvhJMSy36glU6IW9kn30IWuSoBpTkgV7rLUEhh9Ms82VWW/h2Tx L8enfx40PrfbDtWwqRID3WY8jLrjKfTdR3LW8BnUDNkG+c4FzvvGUs8AvuqxxyHbXAfDx9o/ jXfPHVRmJVhSmd+hC3mcQ+4iX5bBPBPMoDqSoLt5w9GoQQ6gDVP2ZjTWqwSRMLzNr37rJjZ1 pt0DCMMTbiYIUcrhX8eveCJtY7NGWNyxFCRkhxRuGcpwPmRVDwOl39MB3iTsRighiMnijkbL XiKoJ5CDVvX5yicNqYJPKh5MFXN1bvsBkmYiStMRbrD0HoY1kx5/VozBtc70OU0EB8Wrv9hZ D+Ofp0T3KOr1RUHvCZoLURfFhSQ= Message-ID: <1109631e-69b1-d506-3e32-e1b80b8b93d9@redhat.com> Date: Wed, 6 Nov 2019 16:41:33 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.1.1 MIME-Version: 1.0 In-Reply-To: <20191106095707-mutt-send-email-mst@kernel.org> Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-MC-Unique: CLBIw6l2Na-xaDOgEuUaIg-1 X-Mimecast-Spam-Score: 0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 06/11/2019 16:03, Michael S. Tsirkin wrote: > On Wed, Nov 06, 2019 at 03:02:25PM +0100, Laurent Vivier wrote: >> On 06/11/2019 14:56, Michael S. Tsirkin wrote: >>> On Fri, Oct 18, 2019 at 06:47:18PM +0200, Laurent Vivier wrote: >>>> When we hot unplug a virtserialport and then try to hot plug again, >>>> it fails: >>>> >>>> (qemu) chardev-add socket,id=3Dserial0,path=3D/tmp/serial0,server,nowa= it >>>> (qemu) device_add virtserialport,bus=3Dvirtio-serial0.0,nr=3D2,\ >>>> chardev=3Dserial0,id=3Dserial0,name=3Dserial0 >>>> (qemu) device_del serial0 >>>> (qemu) device_add virtserialport,bus=3Dvirtio-serial0.0,nr=3D2,\ >>>> chardev=3Dserial0,id=3Dserial0,name=3Dserial0 >>>> kernel error: >>>> virtio-ports vport2p2: Error allocating inbufs >>>> qemu error: >>>> virtio-serial-bus: Guest failure in adding port 2 for device \ >>>> virtio-serial0.0 >>>> >>>> This happens because buffers for the in_vq are allocated when the port= is >>>> added but are not released when the port is unplugged. >>>> >>>> They are only released when virtconsole is removed (see a7a69ec0d8e4) >>>> >>>> To avoid the problem and to be symmetric, we could allocate all the bu= ffers >>>> in init_vqs() as they are released in remove_vqs(), but it sounds like >>>> a waste of memory. >>>> >>>> Rather than that, this patch changes add_port() logic to only allocate= the >>>> buffers if the in_vq has available free slots. >>>> >>>> Fixes: a7a69ec0d8e4 ("virtio_console: free buffers after reset") >>>> Cc: mst@redhat.com >>>> Signed-off-by: Laurent Vivier >>>> --- >>>> drivers/char/virtio_console.c | 17 +++++++++++------ >>>> 1 file changed, 11 insertions(+), 6 deletions(-) >>>> >>>> diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_conso= le.c >>>> index 7270e7b69262..77105166fe01 100644 >>>> --- a/drivers/char/virtio_console.c >>>> +++ b/drivers/char/virtio_console.c >>>> @@ -1421,12 +1421,17 @@ static int add_port(struct ports_device *portd= ev, u32 id) >>>> =09spin_lock_init(&port->outvq_lock); >>>> =09init_waitqueue_head(&port->waitqueue); >>>> =20 >>>> -=09/* Fill the in_vq with buffers so the host can send us data. */ >>>> -=09nr_added_bufs =3D fill_queue(port->in_vq, &port->inbuf_lock); >>>> -=09if (!nr_added_bufs) { >>>> -=09=09dev_err(port->dev, "Error allocating inbufs\n"); >>>> -=09=09err =3D -ENOMEM; >>>> -=09=09goto free_device; >>>> +=09/* if the in_vq has not already been filled (the port has already = been >>>> +=09 * used and unplugged), fill the in_vq with buffers so the host ca= n >>>> +=09 * send us data. >>>> +=09 */ >>>> +=09if (port->in_vq->num_free !=3D 0) { >>>> +=09=09nr_added_bufs =3D fill_queue(port->in_vq, &port->inbuf_lock); >>>> +=09=09if (!nr_added_bufs) { >>>> +=09=09=09dev_err(port->dev, "Error allocating inbufs\n"); >>>> +=09=09=09err =3D -ENOMEM; >>>> +=09=09=09goto free_device; >>>> +=09=09} >>>> =09} >>>> =20 >>>> =09if (is_rproc_serial(port->portdev->vdev)) >>> >>> Well fill_queue will just add slots as long as it can. >>> So on a full queue it does nothing. How does this patch help? >> >> Yes, but in this case it returns 0 and so add_port() fails and exits >> with -ENOMEM and the device is freed. It's what this patch tries to avoi= d. >> >> Thanks, >> Laurent >=20 > Oh I see. However it's a bit asymmetrical to special case ring full. > How about making fill_queue return int and testing return code for > -ENOSPC instead? Will also help propagate errors correctly. Good idea. I'm going to propose a new patch. > And I guess CC stable? Sure. Thanks, Laurent