cfq: Suppress compiler warnings about comparisons

BugLink: https://bugs.launchpad.net/bugs/1835972
[ Upstream commit f7ecb1b109da1006a08d5675debe60990e824432 ]

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>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 9f342ef1ad426fa7d60e00fffeb313409cbbb3f4..9c4f1c496c90c9af5d59bb94be5c24fe48c1debb 100644 (file)
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -4741,12 +4741,13 @@ 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);              \
+                                                                       \
        cfq_var_store(&__data, (page));                                 \
-       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                                                            \
@@ -4775,12 +4776,13 @@ 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);              \
+                                                                       \
        cfq_var_store(&__data, (page));                                 \
-       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 count;                                                   \
 }