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

[Simon Horman <horms@verge.net.au>]

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@oracle.com>
> ---
> v0: First version (internal product).
> v1: Posted on kexec mailing list. Changed -s to -S
> 
> CC: kexec@lists.infradead.org
> CC: xen-devel@lists.xenproject.org
> CC: Daniel Kiper <daniel.kiper@oracle.com>
> ---
>  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
> 
> 
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> kexec mailing list
> kexec@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/kexec
> 

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