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Re: [Qemu-devel] [PATCH v3] bugfix: passing reference instead of value
From: |
Paolo Bonzini |
Subject: |
Re: [Qemu-devel] [PATCH v3] bugfix: passing reference instead of value |
Date: |
Sat, 2 Jan 2016 13:14:49 +0100 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.4.0 |
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 <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.
>
> * 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