From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:49584) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aFL5U-00024q-RI for qemu-devel@nongnu.org; Sat, 02 Jan 2016 07:15:13 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1aFL5P-00070h-RU for qemu-devel@nongnu.org; Sat, 02 Jan 2016 07:15:12 -0500 Received: from plane.gmane.org ([80.91.229.3]:58788) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aFL5P-0006xq-Kg for qemu-devel@nongnu.org; Sat, 02 Jan 2016 07:15:07 -0500 Received: from list by plane.gmane.org with local (Exim 4.69) (envelope-from ) id 1aFL5J-0008Vc-TO for qemu-devel@nongnu.org; Sat, 02 Jan 2016 13:15:02 +0100 Received: from 94-39-190-92.adsl-ull.clienti.tiscali.it ([94.39.190.92]) by main.gmane.org with esmtp (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Sat, 02 Jan 2016 13:15:01 +0100 Received: from pbonzini by 94-39-190-92.adsl-ull.clienti.tiscali.it with local (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Sat, 02 Jan 2016 13:15:01 +0100 From: Paolo Bonzini Date: Sat, 2 Jan 2016 13:14:49 +0100 Message-ID: References: <1451721740-6151-1-git-send-email-caoj.fnst@cn.fujitsu.com> <56879302.3050902@weilnetz.de> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Transfer-Encoding: 7bit In-Reply-To: <56879302.3050902@weilnetz.de> Subject: Re: [Qemu-devel] [PATCH v3] bugfix: passing reference instead of value List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org On 02/01/2016 10:06, Stefan Weil wrote: > Am 02.01.2016 um 09:02 schrieb Cao jin: >> Fix the bug introduced by 595a4f07: function host_pci_config_read() should be >> pass-by-reference, not value. >> >> Signed-off-by: Cao jin >> --- >> v3 changelog: >> 1. Remove cpu_to_le32() since the code only runs on X86. >> >> hw/pci-host/piix.c | 8 +++++--- >> 1 file changed, 5 insertions(+), 3 deletions(-) >> >> diff --git a/hw/pci-host/piix.c b/hw/pci-host/piix.c >> index 715208b..924f0fa 100644 >> --- a/hw/pci-host/piix.c >> +++ b/hw/pci-host/piix.c >> @@ -761,7 +761,7 @@ static const IGDHostInfo igd_host_bridge_infos[] = { >> {0xa8, 4}, /* SNB: base of GTT stolen memory */ >> }; >> >> -static int host_pci_config_read(int pos, int len, uint32_t val) >> +static int host_pci_config_read(int pos, int len, uint32_t *val) >> { >> char path[PATH_MAX]; >> int config_fd; >> @@ -784,12 +784,14 @@ static int host_pci_config_read(int pos, int len, uint32_t val) >> ret = -errno; >> goto out; >> } >> + >> do { >> - rc = read(config_fd, (uint8_t *)&val, len); >> + rc = read(config_fd, (uint8_t *)val, len); > > The type cast is not needed here, because read accepts any pointer > type for the buffer argument. > > While looking at that code, I noticed more potential issues: > > * The open statement needs O_RDWR | O_BINARY, otherwise the code won't > work on Windows. > > * The len argument can obviously be 2 or 4. Will endianness handling > work for both cases? Not sure why this is in pci-host/piix.c, but it's only used on Intel processors and only on Linux. Paolo