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Re: [Xen-devel] [PATCH v1 2/2] kexec: Support -S paramter to return whether the kexec payload is loaded.



On Mon, Nov 14, 2016 at 05:12:53PM -0500, Konrad Rzeszutek Wilk wrote:
> Instead of the scripts having to poke at various fields we can
> provide that functionality via the -S parameter.
> 
> Returns 0 if the payload is loaded. Can be used in combination
> with -l or -p to get the state of the proper kexec image.
> 
> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
> ---
> v0: First version (internal product).
> v1: Posted on kexec mailing list. Changed -s to -S
> 
> CC: kexec@xxxxxxxxxxxxxxxxxxx
> CC: xen-devel@xxxxxxxxxxxxxxxxxxxx
> CC: Daniel Kiper <daniel.kiper@xxxxxxxxxx>
> ---
>  kexec/kexec-xen.c | 20 ++++++++++++++++++
>  kexec/kexec.8     |  5 +++++
>  kexec/kexec.c     | 61 
> ++++++++++++++++++++++++++++++++++++++++++++++++++-----
>  kexec/kexec.h     |  5 ++++-
>  4 files changed, 85 insertions(+), 6 deletions(-)
> 
> diff --git a/kexec/kexec-xen.c b/kexec/kexec-xen.c
> index 24a4191..5a1e9d2 100644
> --- a/kexec/kexec-xen.c
> +++ b/kexec/kexec-xen.c
> @@ -105,6 +105,26 @@ int xen_kexec_unload(uint64_t kexec_flags)
>       return ret;
>  }
>  
> +int xen_kexec_status(uint64_t kexec_flags)
> +{
> +     xc_interface *xch;
> +     uint8_t type;
> +     int ret;
> +
> +     xch = xc_interface_open(NULL, NULL, 0);
> +     if (!xch)
> +             return -1;
> +
> +     type = (kexec_flags & KEXEC_ON_CRASH) ? KEXEC_TYPE_CRASH
> +             : KEXEC_TYPE_DEFAULT;
> +
> +     ret = xc_kexec_status(xch, type);
> +
> +     xc_interface_close(xch);
> +
> +     return ret;
> +}
> +
>  void xen_kexec_exec(void)
>  {
>       xc_interface *xch;
> diff --git a/kexec/kexec.8 b/kexec/kexec.8
> index 4d0c1d1..02f4ccf 100644
> --- a/kexec/kexec.8
> +++ b/kexec/kexec.8
> @@ -107,6 +107,11 @@ command:
>  .B \-d\ (\-\-debug)
>  Enable debugging messages.
>  .TP
> +.B \-D\ (\-\-status)
> +Return 0 if the type (by default crash) is loaded. Can be used in conjuction
> +with -l or -p to toggle the type. Note it will

Is there a mnemonic to map -D to --status?
If not perhaps it would be best to drop the short option.

> +.BR not\ load\ the\ kernel.
> +.TP
>  .B \-e\ (\-\-exec)
>  Run the currently loaded kernel. Note that it will reboot into the loaded 
> kernel without calling shutdown(8).
>  .TP
> diff --git a/kexec/kexec.c b/kexec/kexec.c
> index 500e5a9..bc72688 100644
> --- a/kexec/kexec.c
> +++ b/kexec/kexec.c
> @@ -855,6 +855,32 @@ static int k_unload (unsigned long kexec_flags)
>       return result;
>  }
>  
> +static int kexec_loaded(void);
> +static int __kexec_loaded(const char *f);

I wonder if we could shuffle the location of functions
in this file to avoid the need to forward declarations all together.

> +
> +static int k_status(unsigned long kexec_flags)
> +{
> +     int result;
> +     long native_arch;
> +
> +     /* set the arch */
> +     native_arch = physical_arch();
> +     if (native_arch < 0) {
> +             return -1;
> +     }
> +     kexec_flags |= native_arch;
> +
> +     if (xen_present())
> +             result = xen_kexec_status(kexec_flags);
> +     else {
> +             if (kexec_flags & KEXEC_ON_CRASH)
> +                     result = 
> __kexec_loaded("/sys/kernel/kexec_crash_loaded");
> +             else
> +                     result = kexec_loaded();
> +     }
> +     return result;
> +}
> +
>  /*
>   *   Start a reboot.
>   */
> @@ -890,8 +916,6 @@ static int my_exec(void)
>       return -1;
>  }
>  
> -static int kexec_loaded(void);
> -
>  static int load_jump_back_helper_image(unsigned long kexec_flags, void 
> *entry)
>  {
>       int result;
> @@ -970,6 +994,7 @@ void usage(void)
>              "                      to original kernel.\n"
>              " -s, --kexec-file-syscall Use file based syscall for kexec 
> operation\n"
>              " -d, --debug           Enable debugging to help spot a 
> failure.\n"
> +            " -S, --status         Return 0 if the type (by default crash) 
> is loaded.\n"
>              "\n"
>              "Supported kernel file types and options: \n");
>       for (i = 0; i < file_types; i++) {
> @@ -981,7 +1006,7 @@ void usage(void)
>       printf("\n");
>  }
>  
> -static int kexec_loaded(void)
> +static int __kexec_loaded(const char *file)
>  {
>       long ret = -1;
>       FILE *fp;
> @@ -992,7 +1017,7 @@ static int kexec_loaded(void)
>       if (xen_present())
>               return 1;
>  
> -     fp = fopen("/sys/kernel/kexec_loaded", "r");
> +     fp = fopen(file, "r");
>       if (fp == NULL)
>               return -1;
>  
> @@ -1015,6 +1040,12 @@ static int kexec_loaded(void)
>       return (int)ret;
>  }
>  
> +static int kexec_loaded(void)
> +{
> +     return __kexec_loaded("/sys/kernel/kexec_loaded");
> +}
> +
> +
>  /*
>   * Remove parameter from a kernel command line. Helper function by 
> get_command_line().
>   */
> @@ -1204,6 +1235,7 @@ int main(int argc, char *argv[])
>       int do_unload = 0;
>       int do_reuse_initrd = 0;
> +     int do_status = 0;
>       void *entry = 0;
>       char *type = 0;
>       char *endptr;
> @@ -1345,6 +1377,9 @@ int main(int argc, char *argv[])
>               case OPT_KEXEC_FILE_SYSCALL:
>                       /* We already parsed it. Nothing to do. */
>                       break;
> +             case OPT_STATUS:
> +                     do_status = 1;
> +                     break;
>               default:
>                       break;
>               }
> @@ -1355,6 +1390,20 @@ int main(int argc, char *argv[])
>       if (skip_sync)
>               do_sync = 0;
>  
> +     if (do_status) {
> +             if (kexec_flags == 0)
> +                     kexec_flags = KEXEC_ON_CRASH;
> +             do_load = 0;
> +             do_reuse_initrd = 0;
> +             do_unload = 0;
> +             do_load = 0;
> +             do_shutdown = 0;
> +             do_sync = 0;
> +             do_ifdown = 0;
> +             do_exec = 0;
> +             do_load_jump_back_helper = 0;
> +     }
> +
>       if (do_load && (kexec_flags & KEXEC_ON_CRASH) &&
>           !is_crashkernel_mem_reserved()) {
>               die("Memory for crashkernel is not reserved\n"
> @@ -1392,7 +1441,9 @@ int main(int argc, char *argv[])
>               check_reuse_initrd();
>               arch_reuse_initrd();
>       }
> -
> +     if (do_status) {
> +             result = k_status(kexec_flags);
> +     }
>       if (do_unload) {
>               if (do_kexec_file_syscall)
>                       result = kexec_file_unload(kexec_file_flags);
> diff --git a/kexec/kexec.h b/kexec/kexec.h
> index 9194f1c..2b06f59 100644
> --- a/kexec/kexec.h
> +++ b/kexec/kexec.h
> @@ -219,6 +219,7 @@ extern int file_types;
>  #define OPT_TYPE             't'
>  #define OPT_PANIC            'p'
>  #define OPT_KEXEC_FILE_SYSCALL       's'
> +#define OPT_STATUS           'S'
>  #define OPT_MEM_MIN             256
>  #define OPT_MEM_MAX             257
>  #define OPT_REUSE_INITRD     258
> @@ -245,8 +246,9 @@ extern int file_types;
>       { "reuseinitrd",        0, 0, OPT_REUSE_INITRD }, \
>       { "kexec-file-syscall", 0, 0, OPT_KEXEC_FILE_SYSCALL }, \
>       { "debug",              0, 0, OPT_DEBUG }, \
> +     { "status",             0, 0, OPT_STATUS }, \
>  
> -#define KEXEC_OPT_STR "h?vdfxyluet:ps"
> +#define KEXEC_OPT_STR "h?vdfxyluet:psS"
>  
>  extern void dbgprint_mem_range(const char *prefix, struct memory_range *mr, 
> int nr_mr);
>  extern void die(const char *fmt, ...)
> @@ -311,5 +313,6 @@ int xen_present(void);
>  int xen_kexec_load(struct kexec_info *info);
>  int xen_kexec_unload(uint64_t kexec_flags);
>  void xen_kexec_exec(void);
> +int xen_kexec_status(uint64_t kexec_flags);
>  
>  #endif /* KEXEC_H */
> -- 
> 2.5.5
> 
> 
> _______________________________________________
> kexec mailing list
> kexec@xxxxxxxxxxxxxxxxxxx
> http://lists.infradead.org/mailman/listinfo/kexec
> 

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