Let's simplify return handling.
Signed-off-by: David Hildenbrand <david@redhat.com>
---
arch/x86/xen/mmu_hvm.c | 11 ++---------
1 file changed, 2 insertions(+), 9 deletions(-)
diff --git a/arch/x86/xen/mmu_hvm.c b/arch/x86/xen/mmu_hvm.c
index b242d1f4b426..eb61622df75b 100644
--- a/arch/x86/xen/mmu_hvm.c
+++ b/arch/x86/xen/mmu_hvm.c
@@ -21,23 +21,16 @@ static int xen_oldmem_pfn_is_ram(unsigned long pfn)
.domid = DOMID_SELF,
.pfn = pfn,
};
- int ram;
if (HYPERVISOR_hvm_op(HVMOP_get_mem_type, &a))
return -ENXIO;
switch (a.mem_type) {
case HVMMEM_mmio_dm:
- ram = 0;
- break;
- case HVMMEM_ram_rw:
- case HVMMEM_ram_ro:
+ return 0;
default:
- ram = 1;
- break;
+ return 1;
}
-
- return ram;
}
#endif
--
2.31.1
On 9/28/21 2:22 PM, David Hildenbrand wrote:
> Let's simplify return handling.
>
> Signed-off-by: David Hildenbrand <david@redhat.com>
> ---
> arch/x86/xen/mmu_hvm.c | 11 ++---------
> 1 file changed, 2 insertions(+), 9 deletions(-)
>
> diff --git a/arch/x86/xen/mmu_hvm.c b/arch/x86/xen/mmu_hvm.c
> index b242d1f4b426..eb61622df75b 100644
> --- a/arch/x86/xen/mmu_hvm.c
> +++ b/arch/x86/xen/mmu_hvm.c
> @@ -21,23 +21,16 @@ static int xen_oldmem_pfn_is_ram(unsigned long pfn)
> .domid = DOMID_SELF,
> .pfn = pfn,
> };
> - int ram;
>
> if (HYPERVISOR_hvm_op(HVMOP_get_mem_type, &a))
> return -ENXIO;
>
> switch (a.mem_type) {
> case HVMMEM_mmio_dm:
> - ram = 0;
> - break;
> - case HVMMEM_ram_rw:
> - case HVMMEM_ram_ro:
> + return 0;
> default:
> - ram = 1;
> - break;
> + return 1;
> }
> -
> - return ram;
> }
> #endif
>
How about
return a.mem_type != HVMMEM_mmio_dm;
Result should be promoted to int and this has added benefit of not requiring changes in patch 4.
-boris
>
> How about
>
> return a.mem_type != HVMMEM_mmio_dm;
>
Ha, how could I have missed that :)
>
> Result should be promoted to int and this has added benefit of not requiring changes in patch 4.
>
Can we go one step further and do
@@ -20,24 +20,11 @@ static int xen_oldmem_pfn_is_ram(unsigned long pfn)
struct xen_hvm_get_mem_type a = {
.domid = DOMID_SELF,
.pfn = pfn,
+ .mem_type = HVMMEM_ram_rw,
};
- int ram;
- if (HYPERVISOR_hvm_op(HVMOP_get_mem_type, &a))
- return -ENXIO;
-
- switch (a.mem_type) {
- case HVMMEM_mmio_dm:
- ram = 0;
- break;
- case HVMMEM_ram_rw:
- case HVMMEM_ram_ro:
- default:
- ram = 1;
- break;
- }
-
- return ram;
+ HYPERVISOR_hvm_op(HVMOP_get_mem_type, &a);
+ return a.mem_type != HVMMEM_mmio_dm;
}
#endif
Assuming that if HYPERVISOR_hvm_op() fails that
.mem_type is not set to HVMMEM_mmio_dm.
--
Thanks,
David / dhildenb
On 29.09.21 10:45, David Hildenbrand wrote:
>>
>> How about
>>
>> return a.mem_type != HVMMEM_mmio_dm;
>>
>
> Ha, how could I have missed that :)
>
>>
>> Result should be promoted to int and this has added benefit of not requiring changes in patch 4.
>>
>
> Can we go one step further and do
>
>
> @@ -20,24 +20,11 @@ static int xen_oldmem_pfn_is_ram(unsigned long pfn)
> struct xen_hvm_get_mem_type a = {
> .domid = DOMID_SELF,
> .pfn = pfn,
> + .mem_type = HVMMEM_ram_rw,
> };
> - int ram;
>
> - if (HYPERVISOR_hvm_op(HVMOP_get_mem_type, &a))
> - return -ENXIO;
> -
> - switch (a.mem_type) {
> - case HVMMEM_mmio_dm:
> - ram = 0;
> - break;
> - case HVMMEM_ram_rw:
> - case HVMMEM_ram_ro:
> - default:
> - ram = 1;
> - break;
> - }
> -
> - return ram;
> + HYPERVISOR_hvm_op(HVMOP_get_mem_type, &a);
> + return a.mem_type != HVMMEM_mmio_dm;
> }
> #endif
>
>
> Assuming that if HYPERVISOR_hvm_op() fails that
> .mem_type is not set to HVMMEM_mmio_dm.
>
Okay we can't, due to "__must_check" ...
--
Thanks,
David / dhildenb
On 9/29/21 5:03 AM, David Hildenbrand wrote:
> On 29.09.21 10:45, David Hildenbrand wrote:
>>>
>> Can we go one step further and do
>>
>>
>> @@ -20,24 +20,11 @@ static int xen_oldmem_pfn_is_ram(unsigned long pfn)
>> struct xen_hvm_get_mem_type a = {
>> .domid = DOMID_SELF,
>> .pfn = pfn,
>> + .mem_type = HVMMEM_ram_rw,
>> };
>> - int ram;
>> - if (HYPERVISOR_hvm_op(HVMOP_get_mem_type, &a))
>> - return -ENXIO;
>> -
>> - switch (a.mem_type) {
>> - case HVMMEM_mmio_dm:
>> - ram = 0;
>> - break;
>> - case HVMMEM_ram_rw:
>> - case HVMMEM_ram_ro:
>> - default:
>> - ram = 1;
>> - break;
>> - }
>> -
>> - return ram;
>> + HYPERVISOR_hvm_op(HVMOP_get_mem_type, &a);
>> + return a.mem_type != HVMMEM_mmio_dm;
I was actually thinking of asking you to add another patch with pr_warn_once() here (and print error code as well). This call failing is indication of something going quite wrong and it would be good to know about this.
>> }
>> #endif
>>
>>
>> Assuming that if HYPERVISOR_hvm_op() fails that
>> .mem_type is not set to HVMMEM_mmio_dm.
I don't think we can assume that argument described as OUT in the ABI will not be clobbered in case of error
>>
>
> Okay we can't, due to "__must_check" ...
so this is a good thing ;-)
-boris
On 29.09.21 16:22, Boris Ostrovsky wrote:
>
> On 9/29/21 5:03 AM, David Hildenbrand wrote:
>> On 29.09.21 10:45, David Hildenbrand wrote:
>>>>
>>> Can we go one step further and do
>>>
>>>
>>> @@ -20,24 +20,11 @@ static int xen_oldmem_pfn_is_ram(unsigned long pfn)
>>> struct xen_hvm_get_mem_type a = {
>>> .domid = DOMID_SELF,
>>> .pfn = pfn,
>>> + .mem_type = HVMMEM_ram_rw,
>>> };
>>> - int ram;
>>> - if (HYPERVISOR_hvm_op(HVMOP_get_mem_type, &a))
>>> - return -ENXIO;
>>> -
>>> - switch (a.mem_type) {
>>> - case HVMMEM_mmio_dm:
>>> - ram = 0;
>>> - break;
>>> - case HVMMEM_ram_rw:
>>> - case HVMMEM_ram_ro:
>>> - default:
>>> - ram = 1;
>>> - break;
>>> - }
>>> -
>>> - return ram;
>>> + HYPERVISOR_hvm_op(HVMOP_get_mem_type, &a);
>>> + return a.mem_type != HVMMEM_mmio_dm;
>
>
> I was actually thinking of asking you to add another patch with pr_warn_once() here (and print error code as well). This call failing is indication of something going quite wrong and it would be good to know about this.
Will include a patch in v2, thanks!
--
Thanks,
David / dhildenb
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