[PATCH v2 2/3] iopoll: Avoid evaluating 'cond' twice in poll_timeout_us()

[Ville Syrjala]

From: Ville Syrjälä <ville.syrj...@linux.intel.com>

Currently poll_timeout_us() evaluates 'cond' twice at the end
of the success case. This not desirable in case 'cond' itself
is expensive.

Avoid the double evaluation by tracking the return value in
a variable. Need to use a triple undescore '___ret' name to
avoid a conflict with an existing double undescore '__ret'
variable in the regmap code.

Cc: Lucas De Marchi <lucas.demar...@intel.com>
Cc: Dibin Moolakadan Subrahmanian <dibin.moolakadan.subrahman...@intel.com>
Cc: Imre Deak <imre.d...@intel.com>
Cc: David Laight <david.laight.li...@gmail.com>
Cc: Geert Uytterhoeven <geert+rene...@glider.be>
Cc: Matt Wagantall <ma...@codeaurora.org>
Cc: Dejin Zheng <zhengdej...@gmail.com>
Cc: intel-gfx@lists.freedesktop.org
Cc: intel...@lists.freedesktop.org
Cc: linux-ker...@vger.kernel.org
Reviewed-by: Jani Nikula <jani.nik...@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrj...@linux.intel.com>
---
 include/linux/iopoll.h | 22 ++++++++++++++++++----
 1 file changed, 18 insertions(+), 4 deletions(-)

diff --git a/include/linux/iopoll.h b/include/linux/iopoll.h
index 440aca5b4b59..d8c801ad68fa 100644
--- a/include/linux/iopoll.h
+++ b/include/linux/iopoll.h
@@ -36,23 +36,30 @@
        u64 __timeout_us = (timeout_us); \
        unsigned long __sleep_us = (sleep_us); \
        ktime_t __timeout = ktime_add_us(ktime_get(), __timeout_us); \
+       int ___ret; \
        might_sleep_if((__sleep_us) != 0); \
        if ((sleep_before_op) && __sleep_us) \
                usleep_range((__sleep_us >> 2) + 1, __sleep_us); \
        for (;;) { \
                op; \
-               if (cond) \
+               if (cond) { \
+                       ___ret = 0; \
                        break; \
+               } \
                if (__timeout_us && \
                    ktime_compare(ktime_get(), __timeout) > 0) { \
                        op; \
+                       if (cond) \
+                               ___ret = 0; \
+                       else \
+                               ___ret = -ETIMEDOUT; \
                        break; \
                } \
                if (__sleep_us) \
                        usleep_range((__sleep_us >> 2) + 1, __sleep_us); \
                cpu_relax(); \
        } \
-       (cond) ? 0 : -ETIMEDOUT; \
+       ___ret; \
 })
 
 /**
@@ -83,6 +90,7 @@
        s64 __left_ns = __timeout_us * NSEC_PER_USEC; \
        unsigned long __delay_us = (delay_us); \
        u64 __delay_ns = __delay_us * NSEC_PER_USEC; \
+       int ___ret; \
        if ((delay_before_op) && __delay_us) { \
                udelay(__delay_us); \
                if (__timeout_us) \
@@ -90,10 +98,16 @@
        } \
        for (;;) { \
                op; \
-               if (cond) \
+               if (cond) { \
+                       ___ret = 0; \
                        break; \
+               } \
                if (__timeout_us && __left_ns < 0) { \
                        op; \
+                       if (cond) \
+                               ___ret = 0; \
+                       else \
+                               ___ret = -ETIMEDOUT; \
                        break; \
                } \
                if (__delay_us) { \
@@ -105,7 +119,7 @@
                if (__timeout_us) \
                        __left_ns--; \
        } \
-       (cond) ? 0 : -ETIMEDOUT; \
+       ___ret; \
 })
 
 /**
-- 
2.49.1