ionice: IOPRIO_PRIO_* macros

 * make the code more robust
 * follow kernel conventions for variable names
   (data = classdata, ioprio = classdata | class)

Signed-off-by: Karel Zak <kzak@redhat.com>

diff --git a/schedutils/ionice.c b/schedutils/ionice.c
index 06ddf6d759acd114d838cc40510219f204aa2ff2..f5f53a33a17c6fe1c490b6e468ab1f08efddbfc3 100644 (file)
--- a/schedutils/ionice.c
+++ b/schedutils/ionice.c
@@ -42,33 +42,41 @@ enum {
        IOPRIO_WHO_USER,
 };
 
-#define IOPRIO_CLASS_SHIFT     13
-
-const char *to_prio[] = { "none", "realtime", "best-effort", "idle", };
+#define IOPRIO_CLASS_SHIFT     (13)
+#define IOPRIO_PRIO_MASK       ((1UL << IOPRIO_CLASS_SHIFT) - 1)
+
+#define IOPRIO_PRIO_CLASS(mask)        ((mask) >> IOPRIO_CLASS_SHIFT)
+#define IOPRIO_PRIO_DATA(mask) ((mask) & IOPRIO_PRIO_MASK)
+#define IOPRIO_PRIO_VALUE(class, data) (((class) << IOPRIO_CLASS_SHIFT) | data)
+
+const char *to_prio[] = {
+       [IOPRIO_CLASS_NONE] = "none",
+       [IOPRIO_CLASS_RT]   = "realtime",
+       [IOPRIO_CLASS_BE]   = "best-effort",
+       [IOPRIO_CLASS_IDLE] = "idle"
+};
 
 static void ioprio_print(int pid)
 {
-       int ioprio, ioclass;
-
-       ioprio = ioprio_get(IOPRIO_WHO_PROCESS, pid);
+       int ioprio = ioprio_get(IOPRIO_WHO_PROCESS, pid);
 
        if (ioprio == -1)
                err(EXIT_FAILURE, _("ioprio_get failed"));
        else {
-               ioclass = ioprio >> IOPRIO_CLASS_SHIFT;
-               if (ioclass != IOPRIO_CLASS_IDLE) {
-                       ioprio = ioprio & 0xff;
-                       printf("%s: prio %d\n", to_prio[ioclass], ioprio);
-               } else
+               int ioclass = IOPRIO_PRIO_CLASS(ioprio);
+
+               if (ioclass != IOPRIO_CLASS_IDLE)
+                       printf("%s: prio %lu\n", to_prio[ioclass],
+                                       IOPRIO_PRIO_DATA(ioprio));
+               else
                        printf("%s\n", to_prio[ioclass]);
        }
 }
 
-
-static void ioprio_setpid(pid_t pid, int ioprio, int ioclass)
+static void ioprio_setpid(pid_t pid, int ioclass, int data)
 {
        int rc = ioprio_set(IOPRIO_WHO_PROCESS, pid,
-                       ioprio | ioclass << IOPRIO_CLASS_SHIFT);
+                           IOPRIO_PRIO_VALUE(ioclass, data));
 
        if (rc == -1 && !tolerant)
                err(EXIT_FAILURE, _("ioprio_set failed"));
@@ -100,7 +108,7 @@ static void __attribute__ ((__noreturn__)) usage(FILE * out)
 
 int main(int argc, char *argv[])
 {
-       int ioprio = 4, set = 0, ioclass = IOPRIO_CLASS_BE, c;
+       int data = 4, set = 0, ioclass = IOPRIO_CLASS_BE, c;
        pid_t pid = 0;
 
        static const struct option longopts[] = {
@@ -120,7 +128,7 @@ int main(int argc, char *argv[])
        while ((c = getopt_long(argc, argv, "+n:c:p:tVh", longopts, NULL)) != EOF) {
                switch (c) {
                case 'n':
-                       ioprio = strtol_or_err(optarg, _("failed to parse class data"));
+                       data = strtol_or_err(optarg, _("failed to parse class data"));
                        set |= 1;
                        break;
                case 'c':
@@ -148,7 +156,7 @@ int main(int argc, char *argv[])
                case IOPRIO_CLASS_NONE:
                        if (set & 1)
                                warnx(_("ignoring given class data for none class"));
-                       ioprio = 0;
+                       data = 0;
                        break;
                case IOPRIO_CLASS_RT:
                case IOPRIO_CLASS_BE:
@@ -156,7 +164,7 @@ int main(int argc, char *argv[])
                case IOPRIO_CLASS_IDLE:
                        if (set & 1)
                                warnx(_("ignoring given class data for idle class"));
-                       ioprio = 7;
+                       data = 7;
                        break;
                default:
                        errx(EXIT_FAILURE, _("bad prio class %d"), ioclass);
@@ -171,16 +179,15 @@ int main(int argc, char *argv[])
                }
        } else {
                if (pid) {
-                       ioprio_setpid(pid, ioprio, ioclass);
+                       ioprio_setpid(pid, ioclass, data);
 
-                       for(; argv[optind]; ++optind)
-                       {
+                       for(; argv[optind]; ++optind) {
                                pid = strtol_or_err(argv[optind], _("failed to parse pid"));
-                               ioprio_setpid(pid, ioprio, ioclass);
+                               ioprio_setpid(pid, ioclass, data);
                        }
                }
                else if (argv[optind]) {
-                       ioprio_setpid(0, ioprio, ioclass);
+                       ioprio_setpid(0, ioclass, data);
                        execvp(argv[optind], &argv[optind]);
                        /* execvp should never return */
                        err(EXIT_FAILURE, _("executing %s failed"), argv[optind]);