Re: [Qemu-devel] [PATCH v3 08/21] s390x: move sclp_service_call() to sclp.h

[David Hildenbrand <david@redhat.com>]

On 08.09.2017 06:21, Thomas Huth wrote:
> On 07.09.2017 22:13, David Hildenbrand wrote:
>> Implemented in sclp.c, so let's move it to the right include file.
>> Fix up one include. Do a forward declaration of CPUS390XState to fix the
>> two sclp consoles complaining.
>>
>> Signed-off-by: David Hildenbrand <david@redhat.com>
>> ---
>>  include/hw/s390x/sclp.h    | 2 ++
>>  target/s390x/cpu.h         | 1 -
>>  target/s390x/misc_helper.c | 1 +
>>  3 files changed, 3 insertions(+), 1 deletion(-)
>>
>> diff --git a/include/hw/s390x/sclp.h b/include/hw/s390x/sclp.h
>> index a72d096081..4b86a8a293 100644
>> --- a/include/hw/s390x/sclp.h
>> +++ b/include/hw/s390x/sclp.h
>> @@ -242,5 +242,7 @@ sclpMemoryHotplugDev *init_sclp_memory_hotplug_dev(void);
>>  sclpMemoryHotplugDev *get_sclp_memory_hotplug_dev(void);
>>  void sclp_service_interrupt(uint32_t sccb);
>>  void raise_irq_cpu_hotplug(void);
>> +typedef struct CPUS390XState CPUS390XState;
>> +int sclp_service_call(CPUS390XState *env, uint64_t sccb, uint32_t code);
> 
> That's dangerous and likely does not work with certain versions of GCC.
> You can't do a "forward declaration" with typedef in C, I'm afraid. See
> for example:
> 
>  https://lists.gnu.org/archive/html/qemu-devel/2017-09/msg01454.html
>  https://lists.gnu.org/archive/html/qemu-devel/2017-06/msg03337.html
>  https://stackoverflow.com/questions/8367646/redefinition-of-typedef
> 
> All this typedef'ing in QEMU is pretty bad ... we run into this problem
> again and again. include/qemu/typedefs.h is just a work-around for this.
> I know people like typedefs for some reasons (I used to do that, too,
> before I realized the trouble with them), but IMHO we should rather
> adopt the typedef-related rules from the kernel coding conventions instead:
> 
>  https://www.kernel.org/doc/html/v4.13/process/coding-style.html#typedefs
> 
>   Thomas
> 

Yes, this is really nasty. And I wasn't aware of the involved issues.

This seems to be the only feasible solution (including cpu.h sounds
wrong and will require a bunch of other includes):


diff --git a/include/hw/s390x/sclp.h b/include/hw/s390x/sclp.h
index a72d096081..ce80915a02 100644
--- a/include/hw/s390x/sclp.h
+++ b/include/hw/s390x/sclp.h
@@ -242,5 +242,7 @@ sclpMemoryHotplugDev
*init_sclp_memory_hotplug_dev(void);
 sclpMemoryHotplugDev *get_sclp_memory_hotplug_dev(void);
 void sclp_service_interrupt(uint32_t sccb);
 void raise_irq_cpu_hotplug(void);
+struct CPUS390XState;
+int sclp_service_call(struct CPUS390XState *env, uint64_t sccb,
uint32_t code);

 #endif
diff --git a/target/s390x/cpu.h b/target/s390x/cpu.h
index 3aa2e46aac..032d1de2e8 100644
--- a/target/s390x/cpu.h
+++ b/target/s390x/cpu.h
@@ -721,6 +721,5 @@ int s390_cpu_virt_mem_rw(S390CPU *cpu, vaddr laddr,
uint8_t ar, void *hostbuf,

 /* outside of target/s390x/ */
 S390CPU *s390_cpu_addr2state(uint16_t cpu_addr);
-int sclp_service_call(CPUS390XState *env, uint64_t sccb, uint32_t code);

 #endif
diff --git a/target/s390x/misc_helper.c b/target/s390x/misc_helper.c
index b142db71c6..8b07535b02 100644
--- a/target/s390x/misc_helper.c
+++ b/target/s390x/misc_helper.c
@@ -35,6 +35,7 @@
 #include "sysemu/sysemu.h"
 #include "hw/s390x/ebcdic.h"
 #include "hw/s390x/s390-virtio-hcall.h"
+#include "hw/s390x/sclp.h"
 #endif

 /* #define DEBUG_HELPER */


Opinions?



-- 

Thanks,

David