From: Ville Syrjälä <ville.syrjala@linux.intel.com>
Date: Tue, 26 Aug 2025 12:18:58 +0000 (+0300)
Subject: iopoll: Avoid evaluating 'cond' twice in poll_timeout_us()
X-Git-Tag: v6.18-rc1~134^2~15^2~46
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=563e5eca4ea3b6e1901cbc7cd6dc42731a8d2999;p=thirdparty%2Fkernel%2Flinux.git

iopoll: Avoid evaluating 'cond' twice in poll_timeout_us()

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.demarchi@intel.com>
Cc: Dibin Moolakadan Subrahmanian <dibin.moolakadan.subrahmanian@intel.com>
Cc: Imre Deak <imre.deak@intel.com>
Cc: David Laight <david.laight.linux@gmail.com>
Cc: Geert Uytterhoeven <geert+renesas@glider.be>
Cc: Matt Wagantall <mattw@codeaurora.org>
Cc: Dejin Zheng <zhengdejin5@gmail.com>
Cc: intel-gfx@lists.freedesktop.org
Cc: intel-xe@lists.freedesktop.org
Cc: linux-kernel@vger.kernel.org
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Acked-by: Simona Vetter <simona.vetter@ffwll.ch>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://lore.kernel.org/r/20250826121859.15497-2-ville.syrjala@linux.intel.com
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
---

diff --git a/include/linux/iopoll.h b/include/linux/iopoll.h
index 440aca5b4b59f..d8c801ad68fa6 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; \
 })
 
 /**