Re: [PATCH V13 7/8] gdbstub: Add helper function to unregister GDB register space

[Salil Mehta]

Hi Igor,

On 06/07/2024 14:41, Igor Mammedov wrote:
> On Fri, 7 Jun 2024 12:56:48 +0100
> Salil Mehta <salil.mehta@huawei.com> wrote:
>
> > Add common function to help unregister the GDB register space. This shall be
> > done in context to the CPU unrealization.
> >
> > Note: These are common functions exported to arch specific code. For example,
> > for ARM this code is being referred in associated arch specific patch-set:
> >
> > Link: 
> > https://lore.kernel.org/qemu-devel/20230926103654.34424-1-salil.mehta@huawei.com/
> >
> > Signed-off-by: Salil Mehta <salil.mehta@huawei.com>
> > Tested-by: Vishnu Pajjuri <vishnu@os.amperecomputing.com>
> > Reviewed-by: Gavin Shan <gshan@redhat.com>
> > Tested-by: Xianglai Li <lixianglai@loongson.cn>
> > Tested-by: Miguel Luis <miguel.luis@oracle.com>
> > Reviewed-by: Shaoqin Huang <shahuang@redhat.com>
> > Reviewed-by: Vishnu Pajjuri <vishnu@os.amperecomputing.com>
> > Tested-by: Zhao Liu <zhao1.liu@intel.com>
> > ---
> >   gdbstub/gdbstub.c      | 13 +++++++++++++
> >   hw/core/cpu-common.c   |  1 -
> >   include/exec/gdbstub.h |  6 ++++++
> >   3 files changed, 19 insertions(+), 1 deletion(-)
> >
> > diff --git a/gdbstub/gdbstub.c b/gdbstub/gdbstub.c
> > index b3574997ea..1949b09240 100644
> > --- a/gdbstub/gdbstub.c
> > +++ b/gdbstub/gdbstub.c
> > @@ -617,6 +617,19 @@ void gdb_register_coprocessor(CPUState *cpu,
> >       }
> >   }
> >   
> > +void gdb_unregister_coprocessor_all(CPUState *cpu)
> > +{
> > +    /*
> > +     * Safe to nuke everything. GDBRegisterState::xml is static const char so
> > +     * it won't be freed
> > +     */
> > +    g_array_free(cpu->gdb_regs, true);
> > +
> > +    cpu->gdb_regs = NULL;
> > +    cpu->gdb_num_regs = 0;
> > +    cpu->gdb_num_g_regs = 0;
> > +}
> > +
> >   static void gdb_process_breakpoint_remove_all(GDBProcess *p)
> >   {
> >       CPUState *cpu = gdb_get_first_cpu_in_process(p);
> > diff --git a/hw/core/cpu-common.c b/hw/core/cpu-common.c
> > index 0f0a247f56..e5140b4bc1 100644
> > --- a/hw/core/cpu-common.c
> > +++ b/hw/core/cpu-common.c
> > @@ -274,7 +274,6 @@ static void cpu_common_finalize(Object *obj)
> >   {
> >       CPUState *cpu = CPU(obj);
> >   
> > -    g_array_free(cpu->gdb_regs, TRUE);
> so free() is gone but new  gdb_unregister_coprocessor_all() ain't called,
> are we staring to leak some memory here?

Ah, sorry yes for other architectures. Maybe I can put below check

and keep the free'ing code?

+     if (cpu->gdb_regs)

+ g_array_free(cpu->gdb_regs, TRUE);


Thanks, Salil.

> >       qemu_lockcnt_destroy(&cpu->in_ioctl_lock);
> >       qemu_mutex_destroy(&cpu->work_mutex);
> >   }
> > diff --git a/include/exec/gdbstub.h b/include/exec/gdbstub.h
> > index eb14b91139..249d4d4bc8 100644
> > --- a/include/exec/gdbstub.h
> > +++ b/include/exec/gdbstub.h
> > @@ -49,6 +49,12 @@ void gdb_register_coprocessor(CPUState *cpu,
> >                                 gdb_get_reg_cb get_reg, gdb_set_reg_cb set_reg,
> >                                 const GDBFeature *feature, int g_pos);
> >   
> > +/**
> > + * gdb_unregister_coprocessor_all() - unregisters supplemental set of registers
> > + * @cpu - the CPU associated with registers
> > + */
> > +void gdb_unregister_coprocessor_all(CPUState *cpu);
> > +
> >   /**
> >    * gdbserver_start: start the gdb server
> >    * @port_or_device: connection spec for gdb