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Re: [Qemu-devel] [PATCH v3] bugfix: passing reference instead of value
From: |
Michael S. Tsirkin |
Subject: |
Re: [Qemu-devel] [PATCH v3] bugfix: passing reference instead of value |
Date: |
Sat, 2 Jan 2016 23:37:19 +0200 |
On Sat, Jan 02, 2016 at 10:06:10AM +0100, 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 <address@hidden>
> > ---
> > 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.
I pokes at sysfs, it has no chance to work on windows anyway.
> * The len argument can obviously be 2 or 4. Will endianness handling
> work for both cases?
>
> Regards,
> Stefan
>
>