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

[Eduardo Habkost <ehabkost@redhat.com>]

On Fri, Sep 08, 2017 at 02:46:36PM +0200, David Hildenbrand wrote:
> 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

Why not use typedefs.h?

Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
---
diff --git a/include/hw/s390x/sclp.h b/include/hw/s390x/sclp.h
index 4b86a8a293..3512bf8283 100644
--- a/include/hw/s390x/sclp.h
+++ b/include/hw/s390x/sclp.h
@@ -242,7 +242,6 @@ 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);
 
 #endif
diff --git a/include/qemu/typedefs.h b/include/qemu/typedefs.h
index 39bc8351a3..9c97bffa92 100644
--- a/include/qemu/typedefs.h
+++ b/include/qemu/typedefs.h
@@ -21,6 +21,7 @@ typedef struct Chardev Chardev;
 typedef struct CompatProperty CompatProperty;
 typedef struct CPUAddressSpace CPUAddressSpace;
 typedef struct CPUState CPUState;
+typedef struct CPUS390XState CPUS390XState;
 typedef struct DeviceListener DeviceListener;
 typedef struct DeviceState DeviceState;
 typedef struct DirtyBitmapSnapshot DirtyBitmapSnapshot;
diff --git a/target/s390x/cpu.h b/target/s390x/cpu.h
index 032d1de2e8..f99a82cd5e 100644
--- a/target/s390x/cpu.h
+++ b/target/s390x/cpu.h
@@ -80,7 +80,7 @@ typedef struct MchkQueue {
     uint16_t type;
 } MchkQueue;
 
-typedef struct CPUS390XState {
+struct CPUS390XState {
     uint64_t regs[16];     /* GP registers */
     /*
      * The floating point registers are part of the vector registers.
@@ -174,7 +174,7 @@ typedef struct CPUS390XState {
     /* currently processed sigp order */
     uint8_t sigp_order;
 
-} CPUS390XState;
+};
 
 static inline CPU_DoubleU *get_freg(CPUS390XState *cs, int nr)
 {



> 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

-- 
Eduardo