cfq: Suppress compiler warnings about comparisons

This patch does not change any functionality but avoids that gcc
reports the following warnings when building with W=1:

block/cfq-iosched.c: In function ?cfq_back_seek_max_store?:
block/cfq-iosched.c:4741:13: warning: comparison of unsigned expression < 0 is always false [-Wtype-limits]
  if (__data < (MIN))      \
             ^
block/cfq-iosched.c:4756:1: note: in expansion of macro ?STORE_FUNCTION?
 STORE_FUNCTION(cfq_back_seek_max_store, &cfqd->cfq_back_max, 0, UINT_MAX, 0);
 ^~~~~~~~~~~~~~
block/cfq-iosched.c: In function ?cfq_slice_idle_store?:
block/cfq-iosched.c:4741:13: warning: comparison of unsigned expression < 0 is always false [-Wtype-limits]
  if (__data < (MIN))      \
             ^
block/cfq-iosched.c:4759:1: note: in expansion of macro ?STORE_FUNCTION?
 STORE_FUNCTION(cfq_slice_idle_store, &cfqd->cfq_slice_idle, 0, UINT_MAX, 1);
 ^~~~~~~~~~~~~~
block/cfq-iosched.c: In function ?cfq_group_idle_store?:
block/cfq-iosched.c:4741:13: warning: comparison of unsigned expression < 0 is always false [-Wtype-limits]
  if (__data < (MIN))      \
             ^
block/cfq-iosched.c:4760:1: note: in expansion of macro ?STORE_FUNCTION?
 STORE_FUNCTION(cfq_group_idle_store, &cfqd->cfq_group_idle, 0, UINT_MAX, 1);
 ^~~~~~~~~~~~~~
block/cfq-iosched.c: In function ?cfq_low_latency_store?:
block/cfq-iosched.c:4741:13: warning: comparison of unsigned expression < 0 is always false [-Wtype-limits]
  if (__data < (MIN))      \
             ^
block/cfq-iosched.c:4765:1: note: in expansion of macro ?STORE_FUNCTION?
 STORE_FUNCTION(cfq_low_latency_store, &cfqd->cfq_latency, 0, 1, 0);
 ^~~~~~~~~~~~~~
block/cfq-iosched.c: In function ?cfq_slice_idle_us_store?:
block/cfq-iosched.c:4775:13: warning: comparison of unsigned expression < 0 is always false [-Wtype-limits]
  if (__data < (MIN))      \
             ^
block/cfq-iosched.c:4782:1: note: in expansion of macro ?USEC_STORE_FUNCTION?
 USEC_STORE_FUNCTION(cfq_slice_idle_us_store, &cfqd->cfq_slice_idle, 0, UINT_MAX);
 ^~~~~~~~~~~~~~~~~~~
block/cfq-iosched.c: In function ?cfq_group_idle_us_store?:
block/cfq-iosched.c:4775:13: warning: comparison of unsigned expression < 0 is always false [-Wtype-limits]
  if (__data < (MIN))      \
             ^
block/cfq-iosched.c:4783:1: note: in expansion of macro ?USEC_STORE_FUNCTION?
 USEC_STORE_FUNCTION(cfq_group_idle_us_store, &cfqd->cfq_group_idle, 0, UINT_MAX);
 ^~~~~~~~~~~~~~~~~~~

Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
[wight554: fix 4.4 backport conflicts]
Signed-off-by: Volodymyr Zhdanov <wight554@gmail.com>

diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index ddd515d..af90749 100644 (file)
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -4725,12 +4725,12 @@ USEC_SHOW_FUNCTION(cfq_target_latency_us_show, cfqd->cfq_target_latency);
 static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count)        \
 {                                                                      \
        struct cfq_data *cfqd = e->elevator_data;                       \
-       unsigned int __data;                                            \
+       unsigned int __data, __min = (MIN), __max = (MAX);              \
        int ret = cfq_var_store(&__data, (page), count);                \
-       if (__data < (MIN))                                             \
-               __data = (MIN);                                         \
-       else if (__data > (MAX))                                        \
-               __data = (MAX);                                         \
+       if (__data < __min)                                             \
+               __data = __min;                                         \
+       else if (__data > __max)                                        \
+               __data = __max;                                         \
        if (__CONV)                                                     \
                *(__PTR) = (u64)__data * NSEC_PER_MSEC;                 \
        else                                                            \
@@ -4759,12 +4759,12 @@ STORE_FUNCTION(cfq_target_latency_store, &cfqd->cfq_target_latency, 1, UINT_MAX,
 static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count)        \
 {                                                                      \
        struct cfq_data *cfqd = e->elevator_data;                       \
-       unsigned int __data;                                            \
+       unsigned int __data, __min = (MIN), __max = (MAX);              \
        int ret = cfq_var_store(&__data, (page), count);                \
-       if (__data < (MIN))                                             \
-               __data = (MIN);                                         \
-       else if (__data > (MAX))                                        \
-               __data = (MAX);                                         \
+       if (__data < __min)                                             \
+               __data = __min;                                         \
+       else if (__data > __max)                                        \
+               __data = __max;                                         \
        *(__PTR) = (u64)__data * NSEC_PER_USEC;                         \
        return ret;                                                     \
 }