Re: [Xen-devel] [PATCH 01/11] kexec: add kexec_is_loaded function

[Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>]

On Fri, Jul 29, 2011 at 03:45:23PM +0100, Stefano Stabellini wrote:
> On Thu, 28 Jul 2011, Olaf Hering wrote:
> > Add a new function kexec_is_loaded to be used by subsequent changes for
> > kexec in Xen HVM guests with PV drivers loaded.

.. which is called 'PVonHVM'
> > 
> > A kexec reboot in a HVM guest needs to unregister all resources such as

Not HVM - PVonHVM.
> > xenstore watches and virqs, otherwise the kexec kernel can not bind to
> > these resources again. But the unregister only needs to happen during a
> > kexec boot because the guest remains the same from the Xen point of
> > view. A normal reboot will shutdown and destroy the entire guest with
> > all its resources, then the guest will start again with a different
> > domain_id number. So doing all the unregister work would only delay
> > normal reboots.
> > 
> > Signed-off-by: Olaf Hering <olaf@xxxxxxxxx>

You need to CC the maintainers of these files too.
> > 
> > ---
> >  include/linux/kexec.h |    3 ++-
> >  kernel/kexec.c        |    8 +++++++-
> >  kernel/ksysfs.c       |    2 +-
> >  3 files changed, 10 insertions(+), 3 deletions(-)
> > 
> > Index: linux-3.0/include/linux/kexec.h
> > ===================================================================
> > --- linux-3.0.orig/include/linux/kexec.h
> > +++ linux-3.0/include/linux/kexec.h

And make sure to use git format-patch to come up with the patches.

> > @@ -126,6 +126,7 @@ extern asmlinkage long compat_sys_kexec_
> >  extern struct page *kimage_alloc_control_pages(struct kimage *image,
> >                                             unsigned int order);
> >  extern void crash_kexec(struct pt_regs *);
> > +extern int kexec_is_loaded(void);
> >  int kexec_should_crash(struct task_struct *);
> >  void crash_save_cpu(struct pt_regs *regs, int cpu);
> >  void crash_save_vmcoreinfo(void);
> > @@ -156,7 +157,6 @@ unsigned long paddr_vmcoreinfo_note(void
> >  #define VMCOREINFO_CONFIG(name) \
> >     vmcoreinfo_append_str("CONFIG_%s=y\n", #name)
> >  
> > -extern struct kimage *kexec_image;
> >  extern struct kimage *kexec_crash_image;
> >  
> >  #ifndef kexec_flush_icache_page
> > @@ -214,6 +214,7 @@ void crash_free_reserved_phys_range(unsi
> >  struct pt_regs;
> >  struct task_struct;
> >  static inline void crash_kexec(struct pt_regs *regs) { }
> > +static inline int kexec_is_loaded(void) { return 0; }
> >  static inline int kexec_should_crash(struct task_struct *p) { return 0; }
> >  #endif /* CONFIG_KEXEC */
> >  #endif /* LINUX_KEXEC_H */
> > Index: linux-3.0/kernel/kexec.c
> > ===================================================================
> > --- linux-3.0.orig/kernel/kexec.c
> > +++ linux-3.0/kernel/kexec.c
> > @@ -934,7 +934,7 @@ static int kimage_load_segment(struct ki
> >   * kexec does not sync, or unmount filesystems so if you need
> >   * that to happen you need to do that yourself.
> >   */
> > -struct kimage *kexec_image;
> > +static struct kimage *kexec_image;
> >  struct kimage *kexec_crash_image;
> >  
> >  static DEFINE_MUTEX(kexec_mutex);
> > @@ -1567,3 +1567,9 @@ int kernel_kexec(void)
> >     mutex_unlock(&kexec_mutex);
> >     return error;
> >  }
> > +
> > +int kexec_is_loaded(void)
> > +{
> > +   return !!kexec_image;
> > +}
> > +EXPORT_SYMBOL_GPL(kexec_is_loaded);
> 
> Wouldn't this return true just if a kexec_image is loaded no matter if
> this is a normal shutdown or if it is an actually kexec reboot?
> 
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