From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:46074) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TG3Oz-0002Tf-Mg for qemu-devel@nongnu.org; Mon, 24 Sep 2012 03:48:26 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1TG3Oy-0004rl-1Y for qemu-devel@nongnu.org; Mon, 24 Sep 2012 03:48:25 -0400 Message-ID: <50601043.2080209@redhat.com> Date: Mon, 24 Sep 2012 09:48:19 +0200 From: Kevin Wolf MIME-Version: 1.0 References: <1348072874-2096-1-git-send-email-sw@weilnetz.de> <20120922162920.GB14154@stefanha-thinkpad.localdomain> <505E0916.6030707@weilnetz.de> In-Reply-To: <505E0916.6030707@weilnetz.de> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [Qemu-trivial] [PATCH] pflash: Avoid warnings from coverity List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Stefan Weil Cc: qemu-trivial@nongnu.org, Stefan Hajnoczi , qemu-devel@nongnu.org Am 22.09.2012 20:53, schrieb Stefan Weil: > Am 22.09.2012 18:29, schrieb Stefan Hajnoczi: >> On Wed, Sep 19, 2012 at 06:41:14PM +0200, Stefan Weil wrote: > [snip] >>> offset_end = (offset_end + 511) >> 9; >>> - bdrv_write(pfl->bs, offset, pfl->storage + (offset << 9), >>> - offset_end - offset); >>> + if (bdrv_write(pfl->bs, offset, pfl->storage + (offset << 9), >>> + offset_end - offset) == -1) { >> bdrv_write() returns -errno, not -1. > > Thanks. It looks like we have more code which uses the wrong check > (and which I copied). So more patches are needed. > > Should we also replace code which does bdrv_write() != 0 or !bdrv_write() > by bdrv_write() < 0 to get more uniform code (and the same for bdrv_read*), > even it is not strictly wrong? > > Maybe Kevin as block maintainer should decide that. Yes, I very much prefer ret < 0 checks for all block layer functions. >>> + fprintf(stderr, "pflash: Error writing to flash storage\n"); >>> + } >> Please report the errno and possibly bdrv_get_device_name() to uniquely >> identify this block device. > > That would be overkill here: writing flash memory is not used very > often (even on real hardware it is typically only used for firmware > updates). I expect that anyone who does a firmware update in a > QEMU guest will know the name of the flash image file. > > Usually I replace the flash image file on the QEMU host when I want > to exchange the firmware (much easier than flashing in the guest). > > Reporting errno might be more reasonable.Are there other values than > EIO (e.g. defective media) and ENOSPC (disk full) which could occur? Basically anything that the OS can return. The block layer may internally generate things like -EACCES for writing to read-only images, or -ENOMEDIUM (not sure if it's possible for pflash). > A common solution for all users of bdrv_write in the block layer > would be even better. VirtualBox for example stops the guest when > ENOSPC (disk full) occurs, so it's possible for users to fix that > and resume the emulation. virtio-blk/IDE/scsi-disk do that. >> Peter's comments about reporting errors to the guest make sense to me. >> I'm not sure how much work that involves, printing the error is a step >> in the right direction but we shouldn't forget the TODO. Shouldn't we avoid fprintfs that can be triggered by the guest? Kevin