[PATCH RFC] sched: fix function declaration return type mismatch

[PATCH RFC] sched: fix function declaration return type mismatch

[Nicholas Mc Guire]

static code checking was unhappy with
./kernel/sched/fair.c:162 WARNING: return of wrong type
                int != unsigned int

get_update_sysctl_factor() is declared to return int but is currently 
returning an unsigned int. The first few preprocessed lines are:

 static int get_update_sysctl_factor(void)
 {
 unsigned int cpus = ({ int __min1 = (cpumask_weight(cpu_online_mask));
int __min2 = (8); __min1 < __min2 ? __min1: __min2; });
 unsigned int factor;

min_t should be unsigned int and return type of get_update_sysctl_factor
also unsigned int as its call-site update_sysctl() is expecting unsigned
int and the values utilizing factor sysctl_sched_min_granularity ,
sched_nr_latency and sysctl_sched_wakeup_granularity are also unsigned int
(and cpumask_weight also is returning unsigned int).

Patch was compile tested with x86_64_defconfig + CONFIG_SCHED_DEBUG=y
and changed sections in kernel/sched/fair.i reviewed.

Patch is against 4.1-rc3 (localversion-next is -next-20150514)

Signed-off-by: Nicholas Mc Guire <hofrat@osadl.org>
---
 kernel/sched/fair.c |    6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 8c1510a..a9895b0 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -141,9 +141,9 @@ static inline void update_load_set(struct load_weight *lw, unsigned long w)
  *
  * This idea comes from the SD scheduler of Con Kolivas:
  */
-static int get_update_sysctl_factor(void)
+static unsigned int get_update_sysctl_factor(void)
 {
-	unsigned int cpus = min_t(int, num_online_cpus(), 8);
+	unsigned int cpus = min_t(unsigned int, num_online_cpus(), 8);
 	unsigned int factor;
 
 	switch (sysctl_sched_tunable_scaling) {
@@ -576,7 +576,7 @@ int sched_proc_update_handler(struct ctl_table *table, int write,
 		loff_t *ppos)
 {
 	int ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
-	int factor = get_update_sysctl_factor();
+	unsigned int factor = get_update_sysctl_factor();
 
 	if (ret || !write)
 		return ret;
-- 
1.7.10.4

[tip:sched/core] sched: Fix function declaration return type mismatch

[tip-bot for Nicholas Mc Guire]

Commit-ID:  58ac93e4f2e4b15beffdf0e3749b7fea3208ef66
Gitweb:     http://git.kernel.org/tip/58ac93e4f2e4b15beffdf0e3749b7fea3208ef66
Author:     Nicholas Mc Guire <hofrat@osadl.org>
AuthorDate: Fri, 15 May 2015 21:05:42 +0200
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Sun, 17 May 2015 06:47:46 +0200

sched: Fix function declaration return type mismatch

static code checking was unhappy with:

  ./kernel/sched/fair.c:162 WARNING: return of wrong type
                int != unsigned int

get_update_sysctl_factor() is declared to return int but is
currently  returning an unsigned int. The first few preprocessed
lines are:

 static int get_update_sysctl_factor(void)
 {
 unsigned int cpus = ({ int __min1 = (cpumask_weight(cpu_online_mask));
 int __min2 = (8); __min1 < __min2 ? __min1: __min2; });
 unsigned int factor;

The type used by min_t() should be 'unsigned int' and the return type
of get_update_sysctl_factor() should also be 'unsigned int' as its
call-site update_sysctl() is expecting 'unsigned int' and the values
utilizing:

  'factor'
  'sysctl_sched_min_granularity'
  'sched_nr_latency'
  'sysctl_sched_wakeup_granularity'

... are also all 'unsigned int', plus cpumask_weight() is also
returning 'unsigned int'.

So the natural type to use around here is 'unsigned int'.

( Patch was compile tested with x86_64_defconfig +
  CONFIG_SCHED_DEBUG=y and the changed sections in
  kernel/sched/fair.i were reviewed. )

Signed-off-by: Nicholas Mc Guire <hofrat@osadl.org>
[ Improved the changelog a bit. ]
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1431716742-11077-1-git-send-email-hofrat@osadl.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 kernel/sched/fair.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index f18ddb7..a27d988 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -141,9 +141,9 @@ static inline void update_load_set(struct load_weight *lw, unsigned long w)
  *
  * This idea comes from the SD scheduler of Con Kolivas:
  */
-static int get_update_sysctl_factor(void)
+static unsigned int get_update_sysctl_factor(void)
 {
-	unsigned int cpus = min_t(int, num_online_cpus(), 8);
+	unsigned int cpus = min_t(unsigned int, num_online_cpus(), 8);
 	unsigned int factor;
 
 	switch (sysctl_sched_tunable_scaling) {
@@ -576,7 +576,7 @@ int sched_proc_update_handler(struct ctl_table *table, int write,
 		loff_t *ppos)
 {
 	int ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
-	int factor = get_update_sysctl_factor();
+	unsigned int factor = get_update_sysctl_factor();
 
 	if (ret || !write)
 		return ret;