sched: Use macro for magic number of -1 for setparam

Instead of passing around a magic number -1 for the sched_setparam()
policy, use a more descriptive macro name like SETPARAM_POLICY.

[ based on top of Daniel's sched_setparam() fix ]

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Daniel Bristot de Oliveira<bristot@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/20140723112826.6ed6cbce@gandalf.local.home
Signed-off-by: Ingo Molnar <mingo@kernel.org>

1 files changed, 10 insertions, 7 deletions

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 2a36a74c16ae..2676866b4394 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -3218,12 +3218,18 @@ __setparam_dl(struct task_struct *p, const struct sched_attr *attr)
         dl_se->dl_yielded = 0;
 }
 
+/*
+ * sched_setparam() passes in -1 for its policy, to let the functions
+ * it calls know not to change it.
+ */
+#define SETPARAM_POLICY -1
+
 static void __setscheduler_params(struct task_struct *p,
                 const struct sched_attr *attr)
 {
         int policy = attr->sched_policy;
 
-        if (policy == -1) /* setparam */
+        if (policy == SETPARAM_POLICY)
                 policy = p->policy;
 
         p->policy = policy;
@@ -3572,11 +3578,8 @@ static int _sched_setscheduler(struct task_struct *p, int policy,
                 .sched_nice     = PRIO_TO_NICE(p->static_prio),
         };
 
-        /*
-         * Fixup the legacy SCHED_RESET_ON_FORK hack, except if
-         * the policy=-1 was passed by sched_setparam().
-         */
-        if ((policy != -1) && (policy & SCHED_RESET_ON_FORK)) {
+        /* Fixup the legacy SCHED_RESET_ON_FORK hack. */
+        if ((policy != SETPARAM_POLICY) && (policy & SCHED_RESET_ON_FORK)) {
                 attr.sched_flags |= SCHED_FLAG_RESET_ON_FORK;
                 policy &= ~SCHED_RESET_ON_FORK;
                 attr.sched_policy = policy;
@@ -3746,7 +3749,7 @@ SYSCALL_DEFINE3(sched_setscheduler, pid_t, pid, int, policy,
  */
 SYSCALL_DEFINE2(sched_setparam, pid_t, pid, struct sched_param __user *, param)
 {
-        return do_sched_setscheduler(pid, -1, param);
+        return do_sched_setscheduler(pid, SETPARAM_POLICY, param);
 }
 
 /**