[PATCH v4] kexec: implemented XEN KEXEC STATUS to determine if an image is loaded

[Simon Horman]

On Thu, Jan 26, 2017 at 12:02:48AM +0100, Daniel Kiper wrote:
> On Wed, Jan 25, 2017 at 09:31:15AM -0600, Eric DeVolder wrote:
> 
> [...]
> 
> > diff --git a/kexec/kexec.c b/kexec/kexec.c
> > index 500e5a9..ec16247 100644
> > --- a/kexec/kexec.c
> > +++ b/kexec/kexec.c
> > @@ -51,6 +51,9 @@
> >  #include "kexec-lzma.h"
> >  #include <arch/options.h>
> >
> > +#define KEXEC_LOADED_PATH "/sys/kernel/kexec_loaded"
> > +#define KEXEC_CRASH_LOADED_PATH "/sys/kernel/kexec_crash_loaded"
> > +
> >  unsigned long long mem_min = 0;
> >  unsigned long long mem_max = ULONG_MAX;
> >  static unsigned long kexec_flags = 0;
> > @@ -890,8 +893,6 @@ 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;
> > @@ -902,6 +903,40 @@ static int load_jump_back_helper_image(unsigned long kexec_flags, void *entry)
> >  	return result;
> >  }
> >
> > +static int kexec_loaded(const char *file)
> > +{
> > +	long ret = -1;
> > +	FILE *fp;
> > +	char *p;
> > +	char line[3];
> > +
> > +	/* No way to tell if an image is loaded under Xen, assume it is. */
> > +	if (xen_present())
> > +		return 1;
> > +
> > +	fp = fopen(file, "r");
> > +	if (fp == NULL)
> > +		return -1;
> > +
> > +	p = fgets(line, sizeof(line), fp);
> > +	fclose(fp);
> > +
> > +	if (p == NULL)
> > +		return -1;
> > +
> > +	ret = strtol(line, &p, 10);
> > +
> > +	/* Too long */
> > +	if (ret > INT_MAX)
> > +		return -1;
> > +
> > +	/* No digits were found */
> > +	if (p == line)
> > +		return -1;
> > +
> > +	return (int)ret;
> > +}
> > +
> >  /*
> >   *	Jump back to the original kernel
> >   */
> > @@ -909,7 +944,7 @@ static int my_load_jump_back_helper(unsigned long kexec_flags, void *entry)
> >  {
> >  	int result;
> >
> > -	if (kexec_loaded()) {
> > +	if (kexec_loaded(KEXEC_LOADED_PATH)) {
> >  		fprintf(stderr, "There is kexec kernel loaded, make sure "
> >  			"you are in kexeced kernel.\n");
> >  		return -1;
> > @@ -970,6 +1005,7 @@ 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++) {
> > @@ -981,40 +1017,30 @@ void usage(void)
> >  	printf("\n");
> >  }
> >
> > -static int kexec_loaded(void)
> > +static int k_status(unsigned long kexec_flags)
> >  {
> > -	long ret = -1;
> > -	FILE *fp;
> > -	char *p;
> > -	char line[3];
> > +	int result;
> > +	long native_arch;
> > +
> > +	/* set the arch */
> > +	native_arch = physical_arch();
> > +	if (native_arch < 0) {
> > +		return -1;
> > +	}
> > +	kexec_flags |= native_arch;
> >
> > -	/* No way to tell if an image is loaded under Xen, assume it is. */
> >  	if (xen_present())
> > -		return 1;
> > -
> > -	fp = fopen("/sys/kernel/kexec_loaded", "r");
> > -	if (fp == NULL)
> > -		return -1;
> > -
> > -	p = fgets(line, sizeof(line), fp);
> > -	fclose(fp);
> > -
> > -	if (p == NULL)
> > -		return -1;
> > -
> > -	ret = strtol(line, &p, 10);
> > -
> > -	/* Too long */
> > -	if (ret > INT_MAX)
> > -		return -1;
> > -
> > -	/* No digits were found */
> > -	if (p == line)
> > -		return -1;
> > -
> > -	return (int)ret;
> > +		result = xen_kexec_status(kexec_flags);
> > +	else {
> > +		if (kexec_flags & KEXEC_ON_CRASH)
> > +			result = kexec_loaded(KEXEC_CRASH_LOADED_PATH);
> > +		else
> > +			result = kexec_loaded(KEXEC_LOADED_PATH);
> > +	}
> > +	return result;
> >  }
> 
> Ohhh... This is awful. Have you tried --patience option for "git format-patch"?
> Does it help? If yes please repost. If it does not let's wait for maintainers
> opinion about that. Maybe we should leave forward declaration in first patch
> as is and then move kexec_loaded() in second (as a cleanup).
> 
> Though otherwise LGTM.

It did not seem to help when I tried.

I'm happy with things the way they are and I will apply this patch.