[{"id":1774773,"web_url":"http://patchwork.ozlabs.org/comment/1774773/","msgid":"<20170925144134.GF1859@perard.uk.xensource.com>","list_archive_url":null,"date":"2017-09-25T14:41:34","subject":"Re: [Qemu-devel] [PATCH v2 2/2] xen: dont try setting max grants\n\tmultiple times","submitter":{"id":4759,"url":"http://patchwork.ozlabs.org/api/people/4759/","name":"Anthony PERARD","email":"anthony.perard@citrix.com"},"content":"On Fri, Sep 22, 2017 at 02:07:25PM +0200, Juergen Gross wrote:\n> Trying to call xengnttab_set_max_grants() with the same file handle\n> might fail on some kernels, as this operation is allowed only once.\n> \n> This is a problem for the qdisk backend as blk_connect() can be\n> called multiple times for a domain, e.g. in case grub-xen is being\n> used to boot it.\n> \n> So instead of letting the generic backend code open the gnttab device\n> do it in blk_connect() and close it again in blk_disconnect.\n> \n> Signed-off-by: Juergen Gross \n\nAcked-by: Anthony PERARD \n\nThanks.\n\n> ---\n> V2:\n> - always call blk_disconnect() from blk_free() in order to have the\n> gnttab device node closed (Anthony Perard)\n> ---\n> hw/block/xen_disk.c | 16 ++++++++++++----\n> 1 file changed, 12 insertions(+), 4 deletions(-)\n> \n> diff --git a/hw/block/xen_disk.c b/hw/block/xen_disk.c\n> index 62506e3167..e431bd89e8 100644\n> --- a/hw/block/xen_disk.c\n> +++ b/hw/block/xen_disk.c\n> @@ -1220,6 +1220,12 @@ static int blk_connect(struct XenDevice *xendev)\n> /* Add on the number needed for the ring pages */\n> max_grants += blkdev->nr_ring_ref;\n> \n> + blkdev->xendev.gnttabdev = xengnttab_open(NULL, 0);\n> + if (blkdev->xendev.gnttabdev == NULL) {\n> + xen_pv_printf(xendev, 0, \"xengnttab_open failed: %s\\n\",\n> + strerror(errno));\n> + return -1;\n> + }\n> if (xengnttab_set_max_grants(blkdev->xendev.gnttabdev, max_grants)) {\n> xen_pv_printf(xendev, 0, \"xengnttab_set_max_grants failed: %s\\n\",\n> strerror(errno));\n> @@ -1327,6 +1333,11 @@ static void blk_disconnect(struct XenDevice *xendev)\n> }\n> blkdev->feature_persistent = false;\n> }\n> +\n> + if (blkdev->xendev.gnttabdev) {\n> + xengnttab_close(blkdev->xendev.gnttabdev);\n> + blkdev->xendev.gnttabdev = NULL;\n> + }\n> }\n> \n> static int blk_free(struct XenDevice *xendev)\n> @@ -1334,9 +1345,7 @@ static int blk_free(struct XenDevice *xendev)\n> struct XenBlkDev *blkdev = container_of(xendev, struct XenBlkDev, xendev);\n> struct ioreq *ioreq;\n> \n> - if (blkdev->blk || blkdev->sring) {\n> - blk_disconnect(xendev);\n> - }\n> + blk_disconnect(xendev);\n> \n> while (!QLIST_EMPTY(&blkdev->freelist)) {\n> ioreq = QLIST_FIRST(&blkdev->freelist);\n> @@ -1363,7 +1372,6 @@ static void blk_event(struct XenDevice *xendev)\n> \n> struct XenDevOps xen_blkdev_ops = {\n> .size = sizeof(struct XenBlkDev),\n> - .flags = DEVOPS_FLAG_NEED_GNTDEV,\n> .alloc = blk_alloc,\n> .init = blk_init,\n> .initialise = blk_connect,\n> -- \n> 2.12.3\n>","headers":{"Return-Path":"","X-Original-To":"incoming@patchwork.ozlabs.org","Delivered-To":"patchwork-incoming@bilbo.ozlabs.org","Authentication-Results":"ozlabs.org;\n\tspf=pass (mailfrom) smtp.mailfrom=nongnu.org\n\t(client-ip=2001:4830:134:3::11; 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Mon, 25 Sep 2017 10:42:07 -0400"],"X-IronPort-AV":"E=Sophos;i=\"5.42,436,1500940800\"; d=\"scan'208\";a=\"449108611\"","Date":"Mon, 25 Sep 2017 15:41:34 +0100","From":"Anthony PERARD ","To":"Juergen Gross ","Message-ID":"<20170925144134.GF1859@perard.uk.xensource.com>","References":"<20170922120725.10910-1-jgross@suse.com>\n\t<20170922120725.10910-3-jgross@suse.com>","MIME-Version":"1.0","Content-Type":"text/plain; charset=\"us-ascii\"","Content-Disposition":"inline","In-Reply-To":"<20170922120725.10910-3-jgross@suse.com>","User-Agent":"Mutt/1.9.0 (2017-09-02)","X-detected-operating-system":"by eggs.gnu.org: Genre and OS details not\n\trecognized.","X-Received-From":"66.165.176.63","Subject":"Re: [Qemu-devel] [PATCH v2 2/2] xen: dont try setting max grants\n\tmultiple times","X-BeenThere":"qemu-devel@nongnu.org","X-Mailman-Version":"2.1.21","Precedence":"list","List-Id":"","List-Unsubscribe":",\n\t","List-Archive":"","List-Post":"","List-Help":"","List-Subscribe":",\n\t","Cc":"xen-devel@lists.xenproject.org, sstabellini@kernel.org,\n\tqemu-devel@nongnu.org, kraxel@redhat.com","Errors-To":"qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org","Sender":"\"Qemu-devel\"\n\t"}}]