Xen devel - Sep 2012 - [PATCH] xenpm: make argument parsing and error handling more consistent

Specifically, what values are or aren''t accepted as CPU identifier, and
how the values get interpreted should be consistent across sub-commands
(intended behavior now: non-negative values are okay, and along with
omitting the argument, specifying "all" will also be accepted).

For error handling, error messages should get consistently issued to
stderr, and the tool should now (hopefully) produce an exit code of
zero only in the (partial) success case (there may still be a small
number of questionable cases).

Signed-off-by: Jan Beulich <jbeulich@suse.com>

--- a/tools/misc/xenpm.c
+++ b/tools/misc/xenpm.c
@@ -36,7 +36,7 @@
 #define CPUFREQ_TURBO_ENABLED       1
 
 static xc_interface *xc_handle;
-static int max_cpu_nr;
+static unsigned int max_cpu_nr;
 
 /* help message */
 void show_help(void)
@@ -77,6 +77,33 @@ void help_func(int argc, char *argv[])
     show_help();
 }
 
+static void parse_cpuid(const char *arg, int *cpuid)
+{
+    if ( sscanf(arg, "%d", cpuid) != 1 || *cpuid < 0 )
+    {
+        if ( strcasecmp(arg, "all") )
+        {
+            fprintf(stderr, "Invalid CPU identifier:
''%s''\n", arg);
+            exit(EINVAL);
+        }
+        *cpuid = -1;
+    }
+}
+
+static void parse_cpuid_and_int(int argc, char *argv[],
+                                int *cpuid, int *val, const char *what)
+{
+    if ( argc > 1 )
+        parse_cpuid(argv[0], cpuid);
+
+    if ( argc == 0 || sscanf(argv[argc > 1], "%d", val) != 1 )
+    {
+        fprintf(stderr, argc ? "Invalid %s ''%s''\n"
: "Missing %s\n",
+                what, argv[argc > 1]);
+        exit(EINVAL);
+    }
+}
+
 static void print_cxstat(int cpuid, struct xc_cx_stat *cxstat)
 {
     int i;
@@ -166,7 +193,8 @@ static int show_cxstat_by_cpuid(xc_inter
     if ( ret )
     {
         if ( ret == -ENODEV )
-            printf("Either xen cpuidle is disabled or no valid information
is registered!\n");
+            fprintf(stderr,
+                    "Either Xen cpuidle is disabled or no valid
information is registered!\n");
         return ret;
     }
 
@@ -181,11 +209,8 @@ void cxstat_func(int argc, char *argv[])
 {
     int cpuid = -1;
 
-    if ( argc > 0 && sscanf(argv[0], "%d", &cpuid) !=
1 )
-        cpuid = -1;
-
-    if ( cpuid >= max_cpu_nr )
-        cpuid = -1;
+    if ( argc > 0 )
+        parse_cpuid(argv[0], &cpuid);
 
     show_max_cstate(xc_handle);
 
@@ -294,11 +319,8 @@ void pxstat_func(int argc, char *argv[])
 {
     int cpuid = -1;
 
-    if ( argc > 0 && sscanf(argv[0], "%d", &cpuid) !=
1 )
-        cpuid = -1;
-
-    if ( cpuid >= max_cpu_nr )
-        cpuid = -1;
+    if ( argc > 0 )
+        parse_cpuid(argv[0], &cpuid);
 
     if ( cpuid < 0 )
     {
@@ -338,10 +360,10 @@ static void signal_int_handler(int signo
 	goto out;
     }
 
-    if ( gettimeofday(&tv, NULL) == -1 )
+    if ( gettimeofday(&tv, NULL) )
     {
         fprintf(stderr, "failed to get timeofday\n");
-        goto out ;
+        goto out;
     }
     usec_end = tv.tv_sec * 1000000UL + tv.tv_usec;
 
@@ -541,7 +563,7 @@ void start_gather_func(int argc, char *a
             printf("Timeout set to %d seconds\n", timeout);
     }
 
-    if ( gettimeofday(&tv, NULL) == -1 )
+    if ( gettimeofday(&tv, NULL) )
     {
         fprintf(stderr, "failed to get timeofday\n");
         return ;
@@ -766,11 +788,8 @@ void cpufreq_para_func(int argc, char *a
 {
     int cpuid = -1;
 
-    if ( argc > 0 && sscanf(argv[0], "%d", &cpuid) !=
1 )
-        cpuid = -1;
-
-    if ( cpuid >= max_cpu_nr )
-        cpuid = -1;
+    if ( argc > 0 )
+        parse_cpuid(argv[0], &cpuid);
 
     if ( cpuid < 0 )
     {
@@ -788,26 +807,22 @@ void scaling_max_freq_func(int argc, cha
 {
     int cpuid = -1, freq = -1;
 
-    if ( (argc >= 2 && (sscanf(argv[1], "%d", &freq)
!= 1 ||
-                        sscanf(argv[0], "%d", &cpuid) != 1)) ||
-         (argc == 1 && sscanf(argv[0], "%d", &freq) != 1
) ||
-         argc == 0 )
-    {
-        fprintf(stderr, "failed to set scaling max freq\n");
-        return ;
-    }
+    parse_cpuid_and_int(argc, argv, &cpuid, &freq,
"frequency");
 
     if ( cpuid < 0 )
     {
         int i;
         for ( i = 0; i < max_cpu_nr; i++ )
             if ( xc_set_cpufreq_para(xc_handle, i, SCALING_MAX_FREQ, freq) )
-                fprintf(stderr, "[CPU%d] failed to set scaling max
freq\n", i);
+                fprintf(stderr,
+                        "[CPU%d] failed to set scaling max freq (%d -
%s)\n",
+                        i, errno, strerror(errno));
     }
     else
     {
         if ( xc_set_cpufreq_para(xc_handle, cpuid, SCALING_MAX_FREQ, freq) )
-            fprintf(stderr, "failed to set scaling max freq\n");
+            fprintf(stderr, "failed to set scaling max freq (%d -
%s)\n",
+                    errno, strerror(errno));
     }
 }
 
@@ -815,26 +830,22 @@ void scaling_min_freq_func(int argc, cha
 {
     int cpuid = -1, freq = -1;
 
-    if ( (argc >= 2 && (sscanf(argv[1], "%d", &freq)
!= 1 ||
-                        sscanf(argv[0], "%d", &cpuid) != 1) ) ||
-         (argc == 1 && sscanf(argv[0], "%d", &freq) != 1
) ||
-         argc == 0 )
-    {
-        fprintf(stderr, "failed to set scaling min freq\n");
-        return ;
-    }
+    parse_cpuid_and_int(argc, argv, &cpuid, &freq,
"frequency");
 
     if ( cpuid < 0 )
     {
         int i;
         for ( i = 0; i < max_cpu_nr; i++ )
             if ( xc_set_cpufreq_para(xc_handle, i, SCALING_MIN_FREQ, freq) )
-                fprintf(stderr, "[CPU%d] failed to set scaling min
freq\n", i);
+                fprintf(stderr,
+                        "[CPU%d] failed to set scaling min freq (%d -
%s)\n",
+                        i, errno, strerror(errno));
     }
     else
     {
         if ( xc_set_cpufreq_para(xc_handle, cpuid, SCALING_MIN_FREQ, freq) )
-            fprintf(stderr, "failed to set scaling min freq\n");
+            fprintf(stderr, "failed to set scaling min freq (%d -
%s)\n",
+                    errno, strerror(errno));
     }
 }
 
@@ -842,26 +853,22 @@ void scaling_speed_func(int argc, char *
 {
     int cpuid = -1, speed = -1;
 
-    if ( (argc >= 2 && (sscanf(argv[1], "%d", &speed)
!= 1 ||
-                        sscanf(argv[0], "%d", &cpuid) != 1) ) ||
-         (argc == 1 && sscanf(argv[0], "%d", &speed) != 1
) ||
-         argc == 0 )
-    {
-        fprintf(stderr, "failed to set scaling speed\n");
-        return ;
-    }
+    parse_cpuid_and_int(argc, argv, &cpuid, &speed, "speed");
 
     if ( cpuid < 0 )
     {
         int i;
         for ( i = 0; i < max_cpu_nr; i++ )
             if ( xc_set_cpufreq_para(xc_handle, i, SCALING_SETSPEED, speed) )
-                fprintf(stderr, "[CPU%d] failed to set scaling
speed\n", i);
+                fprintf(stderr,
+                        "[CPU%d] failed to set scaling speed (%d -
%s)\n",
+                        i, errno, strerror(errno));
     }
     else
     {
         if ( xc_set_cpufreq_para(xc_handle, cpuid, SCALING_SETSPEED, speed) )
-            fprintf(stderr, "failed to set scaling speed\n");
+            fprintf(stderr, "failed to set scaling speed (%d -
%s)\n",
+                    errno, strerror(errno));
     }
 }
 
@@ -869,14 +876,7 @@ void scaling_sampling_rate_func(int argc
 {
     int cpuid = -1, rate = -1;
 
-    if ( (argc >= 2 && (sscanf(argv[1], "%d", &rate)
!= 1 ||
-                        sscanf(argv[0], "%d", &cpuid) != 1) ) ||
-         (argc == 1 && sscanf(argv[0], "%d", &rate) != 1
) ||
-         argc == 0 )
-    {
-        fprintf(stderr, "failed to set scaling sampling rate\n");
-        return ;
-    }
+    parse_cpuid_and_int(argc, argv, &cpuid, &rate, "rate");
 
     if ( cpuid < 0 )
     {
@@ -884,12 +884,14 @@ void scaling_sampling_rate_func(int argc
         for ( i = 0; i < max_cpu_nr; i++ )
             if ( xc_set_cpufreq_para(xc_handle, i, SAMPLING_RATE, rate) )
                 fprintf(stderr,
-                        "[CPU%d] failed to set scaling sampling
rate\n", i);
+                        "[CPU%d] failed to set scaling sampling rate (%d -
%s)\n",
+                        i, errno, strerror(errno));
     }
     else
     {
         if ( xc_set_cpufreq_para(xc_handle, cpuid, SAMPLING_RATE, rate) )
-            fprintf(stderr, "failed to set scaling sampling rate\n");
+            fprintf(stderr, "failed to set scaling sampling rate (%d -
%s)\n",
+                    errno, strerror(errno));
     }
 }
 
@@ -897,14 +899,7 @@ void scaling_up_threshold_func(int argc,
 {
     int cpuid = -1, threshold = -1;
 
-    if ( (argc >= 2 && (sscanf(argv[1], "%d",
&threshold) != 1 ||
-                        sscanf(argv[0], "%d", &cpuid) != 1) ) ||
-         (argc == 1 && sscanf(argv[0], "%d", &threshold)
!= 1 ) ||
-         argc == 0 )
-    {
-        fprintf(stderr, "failed to set up scaling threshold\n");
-        return ;
-    }
+    parse_cpuid_and_int(argc, argv, &cpuid, &threshold,
"threshold");
 
     if ( cpuid < 0 )
     {
@@ -912,57 +907,49 @@ void scaling_up_threshold_func(int argc,
         for ( i = 0; i < max_cpu_nr; i++ )
             if ( xc_set_cpufreq_para(xc_handle, i, UP_THRESHOLD, threshold) )
                 fprintf(stderr,
-                        "[CPU%d] failed to set up scaling
threshold\n", i);
+                        "[CPU%d] failed to set up scaling threshold (%d -
%s)\n",
+                        i, errno, strerror(errno));
     }
     else
     {
         if ( xc_set_cpufreq_para(xc_handle, cpuid, UP_THRESHOLD, threshold) )
-            fprintf(stderr, "failed to set up scaling threshold\n");
+            fprintf(stderr, "failed to set up scaling threshold (%d -
%s)\n",
+                    errno, strerror(errno));
     }
 }
 
 void scaling_governor_func(int argc, char *argv[])
 {
     int cpuid = -1;
-    char *name = NULL;
+    char *name;
 
     if ( argc >= 2 )
     {
-        name = strdup(argv[1]);
-        if ( name == NULL )
-            goto out;
-        if ( sscanf(argv[0], "%d", &cpuid) != 1 )
-        {
-            free(name);
-            goto out;
-        }
+        parse_cpuid(argv[0], &cpuid);
+        name = argv[1];
     }
     else if ( argc > 0 )
+        name = argv[0];
+    else
     {
-        name = strdup(argv[0]);
-        if ( name == NULL )
-            goto out;
+        fprintf(stderr, "Missing argument(s)\n");
+        exit(EINVAL);
     }
-    else
-        goto out;
 
     if ( cpuid < 0 )
     {
         int i;
         for ( i = 0; i < max_cpu_nr; i++ )
             if ( xc_set_cpufreq_gov(xc_handle, i, name) )
-                fprintf(stderr, "[CPU%d] failed to set governor
name\n", i);
+                fprintf(stderr, "[CPU%d] failed to set governor name (%d -
%s)\n",
+                        i, errno, strerror(errno));
     }
     else
     {
         if ( xc_set_cpufreq_gov(xc_handle, cpuid, name) )
-            fprintf(stderr, "failed to set governor name\n");
+            fprintf(stderr, "failed to set governor name (%d -
%s)\n",
+                    errno, strerror(errno));
     }
-
-    free(name);
-    return ;
-out:
-    fprintf(stderr, "failed to set governor name\n");
 }
 
 void cpu_topology_func(int argc, char *argv[])
@@ -971,7 +958,7 @@ void cpu_topology_func(int argc, char *a
     DECLARE_HYPERCALL_BUFFER(uint32_t, cpu_to_socket);
     DECLARE_HYPERCALL_BUFFER(uint32_t, cpu_to_node);
     xc_topologyinfo_t info = { 0 };
-    int i;
+    int i, rc = ENOMEM;
 
     cpu_to_core = xc_hypercall_buffer_alloc(xc_handle, cpu_to_core,
sizeof(*cpu_to_core) * MAX_NR_CPU);
     cpu_to_socket = xc_hypercall_buffer_alloc(xc_handle, cpu_to_socket,
sizeof(*cpu_to_socket) * MAX_NR_CPU);
@@ -990,7 +977,9 @@ void cpu_topology_func(int argc, char *a
 
     if ( xc_topologyinfo(xc_handle, &info) )
     {
-        printf("Can not get Xen CPU topology: %d\n", errno);
+        rc = errno;
+        fprintf(stderr, "Cannot get Xen CPU topology (%d - %s)\n",
+                errno, strerror(errno));
         goto out;
     }
 
@@ -1005,116 +994,95 @@ void cpu_topology_func(int argc, char *a
         printf("CPU%d\t %d\t %d\t %d\n",
                i, cpu_to_core[i], cpu_to_socket[i], cpu_to_node[i]);
     }
+    rc = 0;
 out:
     xc_hypercall_buffer_free(xc_handle, cpu_to_core);
     xc_hypercall_buffer_free(xc_handle, cpu_to_socket);
     xc_hypercall_buffer_free(xc_handle, cpu_to_node);
+    if ( rc )
+        exit(rc);
 }
 
 void set_sched_smt_func(int argc, char *argv[])
 {
-    int value, rc;
+    int value;
 
-    if (argc != 1){
-        show_help();
-        exit(-1);
+    if ( argc != 1 ) {
+        fprintf(stderr, "Missing or invalid argument(s)\n");
+        exit(EINVAL);
     }
 
-    if ( !strncmp(argv[0], "disable", sizeof("disable")) )
-    {
+    if ( !strcasecmp(argv[0], "disable") )
         value = 0;
-    }
-    else if ( !strncmp(argv[0], "enable", sizeof("enable"))
)
-    {
+    else if ( !strcasecmp(argv[0], "enable") )
         value = 1;
-    }
     else
     {
-        show_help();
-        exit(-1);
+        fprintf(stderr, "Invalid argument: %s\n", argv[0]);
+        exit(EINVAL);
     }
 
-    rc = xc_set_sched_opt_smt(xc_handle, value);
-    printf("%s sched_smt_power_savings %s\n", argv[0],
-                    rc? "failed":"succeeded" );
-
-    return;
+    if ( !xc_set_sched_opt_smt(xc_handle, value) )
+        printf("%s sched_smt_power_savings succeeded\n", argv[0]);
+    else
+        fprintf(stderr, "%s sched_smt_power_savings failed (%d -
%s)\n",
+                argv[0], errno, strerror(errno));
 }
 
 void set_vcpu_migration_delay_func(int argc, char *argv[])
 {
     int value;
-    int rc;
-
-    if (argc != 1){
-        show_help();
-        exit(-1);
-    }
-
-    value = atoi(argv[0]);
 
-    if (value < 0)
-    {
-        printf("Please try non-negative vcpu migration delay\n");
-        exit(-1);
+    if ( argc != 1 || (value = atoi(argv[0])) < 0 ) {
+        fprintf(stderr, "Missing or invalid argument(s)\n");
+        exit(EINVAL);
     }
 
-    rc = xc_set_vcpu_migration_delay(xc_handle, value);
-    printf("%s to set vcpu migration delay to %d us\n",
-                    rc? "Fail":"Succeed", value );
-
-    return;
+    if ( !xc_set_vcpu_migration_delay(xc_handle, value) )
+        printf("set vcpu migration delay to %d us succeeded\n",
value);
+    else
+        fprintf(stderr, "set vcpu migration delay failed (%d -
%s)\n",
+                errno, strerror(errno));
 }
 
 void get_vcpu_migration_delay_func(int argc, char *argv[])
 {
     uint32_t value;
-    int rc;
 
-    if (argc != 0){
-        show_help();
-        exit(-1);
-    }
+    if ( argc )
+        fprintf(stderr, "Ignoring argument(s)\n");
 
-    rc = xc_get_vcpu_migration_delay(xc_handle, &value);
-    if (!rc)
-    {
-        printf("Schduler vcpu migration delay is %d us\n", value);
-    }
+    if ( !xc_get_vcpu_migration_delay(xc_handle, &value) )
+        printf("Scheduler vcpu migration delay is %d us\n", value);
     else
-    {
-        printf("Failed to get scheduler vcpu migration delay,
errno=%d\n", errno);
-    }
-
-    return;
+        fprintf(stderr,
+                "Failed to get scheduler vcpu migration delay (%d -
%s)\n",
+                errno, strerror(errno));
 }
 
 void set_max_cstate_func(int argc, char *argv[])
 {
-    int value, rc;
+    int value;
 
     if ( argc != 1 || sscanf(argv[0], "%d", &value) != 1 || value
< 0 )
     {
-        show_help();
-        exit(-1);
+        fprintf(stderr, "Missing or invalid argument(s)\n");
+        exit(EINVAL);
     }
 
-    rc = xc_set_cpuidle_max_cstate(xc_handle, (uint32_t)value);
-    printf("set max_cstate to C%d %s\n", value,
-                    rc? "failed":"succeeded" );
-
-    return;
+    if ( !xc_set_cpuidle_max_cstate(xc_handle, (uint32_t)value) )
+        printf("set max_cstate to C%d succeeded\n", value);
+    else
+        fprintf(stderr, "set max_cstate to C%d failed (%d - %s)\n",
+                value, errno, strerror(errno));
 }
 
 void enable_turbo_mode(int argc, char *argv[])
 {
     int cpuid = -1;
 
-    if ( argc > 0 && sscanf(argv[0], "%d", &cpuid) !=
1 )
-        cpuid = -1;
-
-    if ( cpuid >= max_cpu_nr )
-        cpuid = -1;
+    if ( argc > 0 )
+        parse_cpuid(argv[0], &cpuid);
 
     if ( cpuid < 0 )
     {
@@ -1122,21 +1090,22 @@ void enable_turbo_mode(int argc, char *a
          * only make effects on dbs governor */
         int i;
         for ( i = 0; i < max_cpu_nr; i++ )
-            xc_enable_turbo(xc_handle, i);
+            if ( xc_enable_turbo(xc_handle, i) )
+                fprintf(stderr,
+                        "[CPU%d] failed to enable turbo mode (%d -
%s)\n",
+                        i, errno, strerror(errno));
     }
-    else
-        xc_enable_turbo(xc_handle, cpuid);
+    else if ( xc_enable_turbo(xc_handle, cpuid) )
+        fprintf(stderr, "failed to enable turbo mode (%d - %s)\n",
+                errno, strerror(errno));
 }
 
 void disable_turbo_mode(int argc, char *argv[])
 {
     int cpuid = -1;
 
-    if ( argc > 0 && sscanf(argv[0], "%d", &cpuid) !=
1 )
-        cpuid = -1;
-
-    if ( cpuid >= max_cpu_nr )
-        cpuid = -1;
+    if ( argc > 0 )
+        parse_cpuid(argv[0], &cpuid);
 
     if ( cpuid < 0 )
     {
@@ -1144,10 +1113,14 @@ void disable_turbo_mode(int argc, char *
          * only make effects on dbs governor */
         int i;
         for ( i = 0; i < max_cpu_nr; i++ )
-            xc_disable_turbo(xc_handle, i);
+            if ( xc_disable_turbo(xc_handle, i) )
+                fprintf(stderr,
+                        "[CPU%d] failed to disable turbo mode (%d -
%s)\n",
+                        i, errno, strerror(errno));
     }
-    else
-        xc_disable_turbo(xc_handle, cpuid);
+    else if ( xc_disable_turbo(xc_handle, cpuid) )
+        fprintf(stderr, "failed to disable turbo mode (%d - %s)\n",
+                errno, strerror(errno));
 }
 
 struct {
@@ -1191,15 +1164,17 @@ int main(int argc, char *argv[])
     if ( !xc_handle )
     {
         fprintf(stderr, "failed to get the handler\n");
-        return 0;
+        return EIO;
     }
 
     ret = xc_physinfo(xc_handle, &physinfo);
     if ( ret )
     {
-        fprintf(stderr, "failed to get the processor information\n");
+        ret = errno;
+        fprintf(stderr, "failed to get processor information (%d -
%s)\n",
+                ret, strerror(ret));
         xc_interface_close(xc_handle);
-        return 0;
+        return ret;
     }
     max_cpu_nr = physinfo.nr_cpus;
 
@@ -1214,14 +1189,18 @@ int main(int argc, char *argv[])
         for ( i = 0; i < nr_matches; i++ )
             fprintf(stderr, " %s",
main_options[matches_main_options[i]].name);
         fprintf(stderr, "\n");
+        ret = EINVAL;
     }
     else if ( nr_matches == 1 )
         /* dispatch to the corresponding function handler */
         main_options[matches_main_options[0]].function(argc - 2, argv + 2);
     else
+    {
         show_help();
+        ret = EINVAL;
+    }
 
     xc_interface_close(xc_handle);
-    return 0;
+    return ret;
 }
 




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On 14/09/2012 14:02, "Jan Beulich" <JBeulich@suse.com> wrote:
> Specifically, what values are or aren''t accepted as CPU
identifier, and
> how the values get interpreted should be consistent across sub-commands
> (intended behavior now: non-negative values are okay, and along with
> omitting the argument, specifying "all" will also be accepted).
> 
> For error handling, error messages should get consistently issued to
> stderr, and the tool should now (hopefully) produce an exit code of
> zero only in the (partial) success case (there may still be a small
> number of questionable cases).
> 
> Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Keir Fraser <keir@xen.org>

You can apply this one if you get no furthe feedback.

 -- Keir
> --- a/tools/misc/xenpm.c
> +++ b/tools/misc/xenpm.c
> @@ -36,7 +36,7 @@
>  #define CPUFREQ_TURBO_ENABLED       1
>  
>  static xc_interface *xc_handle;
> -static int max_cpu_nr;
> +static unsigned int max_cpu_nr;
>  
>  /* help message */
>  void show_help(void)
> @@ -77,6 +77,33 @@ void help_func(int argc, char *argv[])
>      show_help();
>  }
>  
> +static void parse_cpuid(const char *arg, int *cpuid)
> +{
> +    if ( sscanf(arg, "%d", cpuid) != 1 || *cpuid < 0 )
> +    {
> +        if ( strcasecmp(arg, "all") )
> +        {
> +            fprintf(stderr, "Invalid CPU identifier:
''%s''\n", arg);
> +            exit(EINVAL);
> +        }
> +        *cpuid = -1;
> +    }
> +}
> +
> +static void parse_cpuid_and_int(int argc, char *argv[],
> +                                int *cpuid, int *val, const char *what)
> +{
> +    if ( argc > 1 )
> +        parse_cpuid(argv[0], cpuid);
> +
> +    if ( argc == 0 || sscanf(argv[argc > 1], "%d", val) != 1
)
> +    {
> +        fprintf(stderr, argc ? "Invalid %s
''%s''\n" : "Missing %s\n",
> +                what, argv[argc > 1]);
> +        exit(EINVAL);
> +    }
> +}
> +
>  static void print_cxstat(int cpuid, struct xc_cx_stat *cxstat)
>  {
>      int i;
> @@ -166,7 +193,8 @@ static int show_cxstat_by_cpuid(xc_inter
>      if ( ret )
>      {
>          if ( ret == -ENODEV )
> -            printf("Either xen cpuidle is disabled or no valid
information is
> registered!\n");
> +            fprintf(stderr,
> +                    "Either Xen cpuidle is disabled or no valid
information
> is registered!\n");
>          return ret;
>      }
>  
> @@ -181,11 +209,8 @@ void cxstat_func(int argc, char *argv[])
>  {
>      int cpuid = -1;
>  
> -    if ( argc > 0 && sscanf(argv[0], "%d",
&cpuid) != 1 )
> -        cpuid = -1;
> -
> -    if ( cpuid >= max_cpu_nr )
> -        cpuid = -1;
> +    if ( argc > 0 )
> +        parse_cpuid(argv[0], &cpuid);
>  
>      show_max_cstate(xc_handle);
>  
> @@ -294,11 +319,8 @@ void pxstat_func(int argc, char *argv[])
>  {
>      int cpuid = -1;
>  
> -    if ( argc > 0 && sscanf(argv[0], "%d",
&cpuid) != 1 )
> -        cpuid = -1;
> -
> -    if ( cpuid >= max_cpu_nr )
> -        cpuid = -1;
> +    if ( argc > 0 )
> +        parse_cpuid(argv[0], &cpuid);
>  
>      if ( cpuid < 0 )
>      {
> @@ -338,10 +360,10 @@ static void signal_int_handler(int signo
> goto out;
>      }
>  
> -    if ( gettimeofday(&tv, NULL) == -1 )
> +    if ( gettimeofday(&tv, NULL) )
>      {
>          fprintf(stderr, "failed to get timeofday\n");
> -        goto out ;
> +        goto out;
>      }
>      usec_end = tv.tv_sec * 1000000UL + tv.tv_usec;
>  
> @@ -541,7 +563,7 @@ void start_gather_func(int argc, char *a
>              printf("Timeout set to %d seconds\n", timeout);
>      }
>  
> -    if ( gettimeofday(&tv, NULL) == -1 )
> +    if ( gettimeofday(&tv, NULL) )
>      {
>          fprintf(stderr, "failed to get timeofday\n");
>          return ;
> @@ -766,11 +788,8 @@ void cpufreq_para_func(int argc, char *a
>  {
>      int cpuid = -1;
>  
> -    if ( argc > 0 && sscanf(argv[0], "%d",
&cpuid) != 1 )
> -        cpuid = -1;
> -
> -    if ( cpuid >= max_cpu_nr )
> -        cpuid = -1;
> +    if ( argc > 0 )
> +        parse_cpuid(argv[0], &cpuid);
>  
>      if ( cpuid < 0 )
>      {
> @@ -788,26 +807,22 @@ void scaling_max_freq_func(int argc, cha
>  {
>      int cpuid = -1, freq = -1;
>  
> -    if ( (argc >= 2 && (sscanf(argv[1], "%d",
&freq) != 1 ||
> -                        sscanf(argv[0], "%d", &cpuid) != 1))
||
> -         (argc == 1 && sscanf(argv[0], "%d", &freq)
!= 1 ) ||
> -         argc == 0 )
> -    {
> -        fprintf(stderr, "failed to set scaling max freq\n");
> -        return ;
> -    }
> +    parse_cpuid_and_int(argc, argv, &cpuid, &freq,
"frequency");
>  
>      if ( cpuid < 0 )
>      {
>          int i;
>          for ( i = 0; i < max_cpu_nr; i++ )
>              if ( xc_set_cpufreq_para(xc_handle, i, SCALING_MAX_FREQ, freq)
)
> -                fprintf(stderr, "[CPU%d] failed to set scaling max
freq\n",
> i);
> +                fprintf(stderr,
> +                        "[CPU%d] failed to set scaling max freq (%d -
%s)\n",
> +                        i, errno, strerror(errno));
>      }
>      else
>      {
>          if ( xc_set_cpufreq_para(xc_handle, cpuid, SCALING_MAX_FREQ, freq)
)
> -            fprintf(stderr, "failed to set scaling max freq\n");
> +            fprintf(stderr, "failed to set scaling max freq (%d -
%s)\n",
> +                    errno, strerror(errno));
>      }
>  }
>  
> @@ -815,26 +830,22 @@ void scaling_min_freq_func(int argc, cha
>  {
>      int cpuid = -1, freq = -1;
>  
> -    if ( (argc >= 2 && (sscanf(argv[1], "%d",
&freq) != 1 ||
> -                        sscanf(argv[0], "%d", &cpuid) != 1)
) ||
> -         (argc == 1 && sscanf(argv[0], "%d", &freq)
!= 1 ) ||
> -         argc == 0 )
> -    {
> -        fprintf(stderr, "failed to set scaling min freq\n");
> -        return ;
> -    }
> +    parse_cpuid_and_int(argc, argv, &cpuid, &freq,
"frequency");
>  
>      if ( cpuid < 0 )
>      {
>          int i;
>          for ( i = 0; i < max_cpu_nr; i++ )
>              if ( xc_set_cpufreq_para(xc_handle, i, SCALING_MIN_FREQ, freq)
)
> -                fprintf(stderr, "[CPU%d] failed to set scaling min
freq\n",
> i);
> +                fprintf(stderr,
> +                        "[CPU%d] failed to set scaling min freq (%d -
%s)\n",
> +                        i, errno, strerror(errno));
>      }
>      else
>      {
>          if ( xc_set_cpufreq_para(xc_handle, cpuid, SCALING_MIN_FREQ, freq)
)
> -            fprintf(stderr, "failed to set scaling min freq\n");
> +            fprintf(stderr, "failed to set scaling min freq (%d -
%s)\n",
> +                    errno, strerror(errno));
>      }
>  }
>  
> @@ -842,26 +853,22 @@ void scaling_speed_func(int argc, char *
>  {
>      int cpuid = -1, speed = -1;
>  
> -    if ( (argc >= 2 && (sscanf(argv[1], "%d",
&speed) != 1 ||
> -                        sscanf(argv[0], "%d", &cpuid) != 1)
) ||
> -         (argc == 1 && sscanf(argv[0], "%d", &speed)
!= 1 ) ||
> -         argc == 0 )
> -    {
> -        fprintf(stderr, "failed to set scaling speed\n");
> -        return ;
> -    }
> +    parse_cpuid_and_int(argc, argv, &cpuid, &speed,
"speed");
>  
>      if ( cpuid < 0 )
>      {
>          int i;
>          for ( i = 0; i < max_cpu_nr; i++ )
>              if ( xc_set_cpufreq_para(xc_handle, i, SCALING_SETSPEED,
speed) )
> -                fprintf(stderr, "[CPU%d] failed to set scaling
speed\n", i);
> +                fprintf(stderr,
> +                        "[CPU%d] failed to set scaling speed (%d -
%s)\n",
> +                        i, errno, strerror(errno));
>      }
>      else
>      {
>          if ( xc_set_cpufreq_para(xc_handle, cpuid, SCALING_SETSPEED,
speed) )
> -            fprintf(stderr, "failed to set scaling speed\n");
> +            fprintf(stderr, "failed to set scaling speed (%d -
%s)\n",
> +                    errno, strerror(errno));
>      }
>  }
>  
> @@ -869,14 +876,7 @@ void scaling_sampling_rate_func(int argc
>  {
>      int cpuid = -1, rate = -1;
>  
> -    if ( (argc >= 2 && (sscanf(argv[1], "%d",
&rate) != 1 ||
> -                        sscanf(argv[0], "%d", &cpuid) != 1)
) ||
> -         (argc == 1 && sscanf(argv[0], "%d", &rate)
!= 1 ) ||
> -         argc == 0 )
> -    {
> -        fprintf(stderr, "failed to set scaling sampling
rate\n");
> -        return ;
> -    }
> +    parse_cpuid_and_int(argc, argv, &cpuid, &rate,
"rate");
>  
>      if ( cpuid < 0 )
>      {
> @@ -884,12 +884,14 @@ void scaling_sampling_rate_func(int argc
>          for ( i = 0; i < max_cpu_nr; i++ )
>              if ( xc_set_cpufreq_para(xc_handle, i, SAMPLING_RATE, rate) )
>                  fprintf(stderr,
> -                        "[CPU%d] failed to set scaling sampling
rate\n", i);
> +                        "[CPU%d] failed to set scaling sampling rate
(%d -
> %s)\n",
> +                        i, errno, strerror(errno));
>      }
>      else
>      {
>          if ( xc_set_cpufreq_para(xc_handle, cpuid, SAMPLING_RATE, rate) )
> -            fprintf(stderr, "failed to set scaling sampling
rate\n");
> +            fprintf(stderr, "failed to set scaling sampling rate (%d
-
> %s)\n",
> +                    errno, strerror(errno));
>      }
>  }
>  
> @@ -897,14 +899,7 @@ void scaling_up_threshold_func(int argc,
>  {
>      int cpuid = -1, threshold = -1;
>  
> -    if ( (argc >= 2 && (sscanf(argv[1], "%d",
&threshold) != 1 ||
> -                        sscanf(argv[0], "%d", &cpuid) != 1)
) ||
> -         (argc == 1 && sscanf(argv[0], "%d",
&threshold) != 1 ) ||
> -         argc == 0 )
> -    {
> -        fprintf(stderr, "failed to set up scaling threshold\n");
> -        return ;
> -    }
> +    parse_cpuid_and_int(argc, argv, &cpuid, &threshold,
"threshold");
>  
>      if ( cpuid < 0 )
>      {
> @@ -912,57 +907,49 @@ void scaling_up_threshold_func(int argc,
>          for ( i = 0; i < max_cpu_nr; i++ )
>              if ( xc_set_cpufreq_para(xc_handle, i, UP_THRESHOLD,
threshold) )
>                  fprintf(stderr,
> -                        "[CPU%d] failed to set up scaling
threshold\n", i);
> +                        "[CPU%d] failed to set up scaling threshold
(%d -
> %s)\n",
> +                        i, errno, strerror(errno));
>      }
>      else
>      {
>          if ( xc_set_cpufreq_para(xc_handle, cpuid, UP_THRESHOLD,
threshold) )
> -            fprintf(stderr, "failed to set up scaling
threshold\n");
> +            fprintf(stderr, "failed to set up scaling threshold (%d -
%s)\n",
> +                    errno, strerror(errno));
>      }
>  }
>  
>  void scaling_governor_func(int argc, char *argv[])
>  {
>      int cpuid = -1;
> -    char *name = NULL;
> +    char *name;
>  
>      if ( argc >= 2 )
>      {
> -        name = strdup(argv[1]);
> -        if ( name == NULL )
> -            goto out;
> -        if ( sscanf(argv[0], "%d", &cpuid) != 1 )
> -        {
> -            free(name);
> -            goto out;
> -        }
> +        parse_cpuid(argv[0], &cpuid);
> +        name = argv[1];
>      }
>      else if ( argc > 0 )
> +        name = argv[0];
> +    else
>      {
> -        name = strdup(argv[0]);
> -        if ( name == NULL )
> -            goto out;
> +        fprintf(stderr, "Missing argument(s)\n");
> +        exit(EINVAL);
>      }
> -    else
> -        goto out;
>  
>      if ( cpuid < 0 )
>      {
>          int i;
>          for ( i = 0; i < max_cpu_nr; i++ )
>              if ( xc_set_cpufreq_gov(xc_handle, i, name) )
> -                fprintf(stderr, "[CPU%d] failed to set governor
name\n", i);
> +                fprintf(stderr, "[CPU%d] failed to set governor name
(%d -
> %s)\n",
> +                        i, errno, strerror(errno));
>      }
>      else
>      {
>          if ( xc_set_cpufreq_gov(xc_handle, cpuid, name) )
> -            fprintf(stderr, "failed to set governor name\n");
> +            fprintf(stderr, "failed to set governor name (%d -
%s)\n",
> +                    errno, strerror(errno));
>      }
> -
> -    free(name);
> -    return ;
> -out:
> -    fprintf(stderr, "failed to set governor name\n");
>  }
>  
>  void cpu_topology_func(int argc, char *argv[])
> @@ -971,7 +958,7 @@ void cpu_topology_func(int argc, char *a
>      DECLARE_HYPERCALL_BUFFER(uint32_t, cpu_to_socket);
>      DECLARE_HYPERCALL_BUFFER(uint32_t, cpu_to_node);
>      xc_topologyinfo_t info = { 0 };
> -    int i;
> +    int i, rc = ENOMEM;
>  
>      cpu_to_core = xc_hypercall_buffer_alloc(xc_handle, cpu_to_core,
> sizeof(*cpu_to_core) * MAX_NR_CPU);
>      cpu_to_socket = xc_hypercall_buffer_alloc(xc_handle, cpu_to_socket,
> sizeof(*cpu_to_socket) * MAX_NR_CPU);
> @@ -990,7 +977,9 @@ void cpu_topology_func(int argc, char *a
>  
>      if ( xc_topologyinfo(xc_handle, &info) )
>      {
> -        printf("Can not get Xen CPU topology: %d\n", errno);
> +        rc = errno;
> +        fprintf(stderr, "Cannot get Xen CPU topology (%d -
%s)\n",
> +                errno, strerror(errno));
>          goto out;
>      }
>  
> @@ -1005,116 +994,95 @@ void cpu_topology_func(int argc, char *a
>          printf("CPU%d\t %d\t %d\t %d\n",
>                 i, cpu_to_core[i], cpu_to_socket[i], cpu_to_node[i]);
>      }
> +    rc = 0;
>  out:
>      xc_hypercall_buffer_free(xc_handle, cpu_to_core);
>      xc_hypercall_buffer_free(xc_handle, cpu_to_socket);
>      xc_hypercall_buffer_free(xc_handle, cpu_to_node);
> +    if ( rc )
> +        exit(rc);
>  }
>  
>  void set_sched_smt_func(int argc, char *argv[])
>  {
> -    int value, rc;
> +    int value;
>  
> -    if (argc != 1){
> -        show_help();
> -        exit(-1);
> +    if ( argc != 1 ) {
> +        fprintf(stderr, "Missing or invalid argument(s)\n");
> +        exit(EINVAL);
>      }
>  
> -    if ( !strncmp(argv[0], "disable",
sizeof("disable")) )
> -    {
> +    if ( !strcasecmp(argv[0], "disable") )
>          value = 0;
> -    }
> -    else if ( !strncmp(argv[0], "enable",
sizeof("enable")) )
> -    {
> +    else if ( !strcasecmp(argv[0], "enable") )
>          value = 1;
> -    }
>      else
>      {
> -        show_help();
> -        exit(-1);
> +        fprintf(stderr, "Invalid argument: %s\n", argv[0]);
> +        exit(EINVAL);
>      }
>  
> -    rc = xc_set_sched_opt_smt(xc_handle, value);
> -    printf("%s sched_smt_power_savings %s\n", argv[0],
> -                    rc? "failed":"succeeded" );
> -
> -    return;
> +    if ( !xc_set_sched_opt_smt(xc_handle, value) )
> +        printf("%s sched_smt_power_savings succeeded\n",
argv[0]);
> +    else
> +        fprintf(stderr, "%s sched_smt_power_savings failed (%d -
%s)\n",
> +                argv[0], errno, strerror(errno));
>  }
>  
>  void set_vcpu_migration_delay_func(int argc, char *argv[])
>  {
>      int value;
> -    int rc;
> -
> -    if (argc != 1){
> -        show_help();
> -        exit(-1);
> -    }
> -
> -    value = atoi(argv[0]);
>  
> -    if (value < 0)
> -    {
> -        printf("Please try non-negative vcpu migration
delay\n");
> -        exit(-1);
> +    if ( argc != 1 || (value = atoi(argv[0])) < 0 ) {
> +        fprintf(stderr, "Missing or invalid argument(s)\n");
> +        exit(EINVAL);
>      }
>  
> -    rc = xc_set_vcpu_migration_delay(xc_handle, value);
> -    printf("%s to set vcpu migration delay to %d us\n",
> -                    rc? "Fail":"Succeed", value );
> -
> -    return;
> +    if ( !xc_set_vcpu_migration_delay(xc_handle, value) )
> +        printf("set vcpu migration delay to %d us succeeded\n",
value);
> +    else
> +        fprintf(stderr, "set vcpu migration delay failed (%d -
%s)\n",
> +                errno, strerror(errno));
>  }
>  
>  void get_vcpu_migration_delay_func(int argc, char *argv[])
>  {
>      uint32_t value;
> -    int rc;
>  
> -    if (argc != 0){
> -        show_help();
> -        exit(-1);
> -    }
> +    if ( argc )
> +        fprintf(stderr, "Ignoring argument(s)\n");
>  
> -    rc = xc_get_vcpu_migration_delay(xc_handle, &value);
> -    if (!rc)
> -    {
> -        printf("Schduler vcpu migration delay is %d us\n",
value);
> -    }
> +    if ( !xc_get_vcpu_migration_delay(xc_handle, &value) )
> +        printf("Scheduler vcpu migration delay is %d us\n",
value);
>      else
> -    {
> -        printf("Failed to get scheduler vcpu migration delay,
errno=%d\n",
> errno);
> -    }
> -
> -    return;
> +        fprintf(stderr,
> +                "Failed to get scheduler vcpu migration delay (%d -
%s)\n",
> +                errno, strerror(errno));
>  }
>  
>  void set_max_cstate_func(int argc, char *argv[])
>  {
> -    int value, rc;
> +    int value;
>  
>      if ( argc != 1 || sscanf(argv[0], "%d", &value) != 1 ||
value < 0 )
>      {
> -        show_help();
> -        exit(-1);
> +        fprintf(stderr, "Missing or invalid argument(s)\n");
> +        exit(EINVAL);
>      }
>  
> -    rc = xc_set_cpuidle_max_cstate(xc_handle, (uint32_t)value);
> -    printf("set max_cstate to C%d %s\n", value,
> -                    rc? "failed":"succeeded" );
> -
> -    return;
> +    if ( !xc_set_cpuidle_max_cstate(xc_handle, (uint32_t)value) )
> +        printf("set max_cstate to C%d succeeded\n", value);
> +    else
> +        fprintf(stderr, "set max_cstate to C%d failed (%d -
%s)\n",
> +                value, errno, strerror(errno));
>  }
>  
>  void enable_turbo_mode(int argc, char *argv[])
>  {
>      int cpuid = -1;
>  
> -    if ( argc > 0 && sscanf(argv[0], "%d",
&cpuid) != 1 )
> -        cpuid = -1;
> -
> -    if ( cpuid >= max_cpu_nr )
> -        cpuid = -1;
> +    if ( argc > 0 )
> +        parse_cpuid(argv[0], &cpuid);
>  
>      if ( cpuid < 0 )
>      {
> @@ -1122,21 +1090,22 @@ void enable_turbo_mode(int argc, char *a
>           * only make effects on dbs governor */
>          int i;
>          for ( i = 0; i < max_cpu_nr; i++ )
> -            xc_enable_turbo(xc_handle, i);
> +            if ( xc_enable_turbo(xc_handle, i) )
> +                fprintf(stderr,
> +                        "[CPU%d] failed to enable turbo mode (%d -
%s)\n",
> +                        i, errno, strerror(errno));
>      }
> -    else
> -        xc_enable_turbo(xc_handle, cpuid);
> +    else if ( xc_enable_turbo(xc_handle, cpuid) )
> +        fprintf(stderr, "failed to enable turbo mode (%d -
%s)\n",
> +                errno, strerror(errno));
>  }
>  
>  void disable_turbo_mode(int argc, char *argv[])
>  {
>      int cpuid = -1;
>  
> -    if ( argc > 0 && sscanf(argv[0], "%d",
&cpuid) != 1 )
> -        cpuid = -1;
> -
> -    if ( cpuid >= max_cpu_nr )
> -        cpuid = -1;
> +    if ( argc > 0 )
> +        parse_cpuid(argv[0], &cpuid);
>  
>      if ( cpuid < 0 )
>      {
> @@ -1144,10 +1113,14 @@ void disable_turbo_mode(int argc, char *
>           * only make effects on dbs governor */
>          int i;
>          for ( i = 0; i < max_cpu_nr; i++ )
> -            xc_disable_turbo(xc_handle, i);
> +            if ( xc_disable_turbo(xc_handle, i) )
> +                fprintf(stderr,
> +                        "[CPU%d] failed to disable turbo mode (%d -
%s)\n",
> +                        i, errno, strerror(errno));
>      }
> -    else
> -        xc_disable_turbo(xc_handle, cpuid);
> +    else if ( xc_disable_turbo(xc_handle, cpuid) )
> +        fprintf(stderr, "failed to disable turbo mode (%d -
%s)\n",
> +                errno, strerror(errno));
>  }
>  
>  struct {
> @@ -1191,15 +1164,17 @@ int main(int argc, char *argv[])
>      if ( !xc_handle )
>      {
>          fprintf(stderr, "failed to get the handler\n");
> -        return 0;
> +        return EIO;
>      }
>  
>      ret = xc_physinfo(xc_handle, &physinfo);
>      if ( ret )
>      {
> -        fprintf(stderr, "failed to get the processor
information\n");
> +        ret = errno;
> +        fprintf(stderr, "failed to get processor information (%d -
%s)\n",
> +                ret, strerror(ret));
>          xc_interface_close(xc_handle);
> -        return 0;
> +        return ret;
>      }
>      max_cpu_nr = physinfo.nr_cpus;
>  
> @@ -1214,14 +1189,18 @@ int main(int argc, char *argv[])
>          for ( i = 0; i < nr_matches; i++ )
>              fprintf(stderr, " %s",
> main_options[matches_main_options[i]].name);
>          fprintf(stderr, "\n");
> +        ret = EINVAL;
>      }
>      else if ( nr_matches == 1 )
>          /* dispatch to the corresponding function handler */
>          main_options[matches_main_options[0]].function(argc - 2, argv +
2);
>      else
> +    {
>          show_help();
> +        ret = EINVAL;
> +    }
>  
>      xc_interface_close(xc_handle);
> -    return 0;
> +    return ret;
>  }
>  
> 
> 
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