Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1697096 > unrolled thread

[PATCH] [v2] iopoll: avoid -Wint-in-bool-context warning

Back to article view | Back to linux.kernel

Contents

  [PATCH] [v2] iopoll: avoid -Wint-in-bool-context warning Arnd Bergmann <arnd@arndb.de> - 2017-07-26 15:40 +0200
    Re: [PATCH] [v2] iopoll: avoid -Wint-in-bool-context warning Mark Brown <broonie@kernel.org> - 2017-07-26 16:30 +0200
      Re: [PATCH] [v2] iopoll: avoid -Wint-in-bool-context warning Andrew Morton <akpm@linux-foundation.org> - 2017-07-26 23:40 +0200
        Re: [PATCH] [v2] iopoll: avoid -Wint-in-bool-context warning Mark Brown <broonie@kernel.org> - 2017-07-27 12:00 +0200
    Re: [PATCH] [v2] iopoll: avoid -Wint-in-bool-context warning Andrew Morton <akpm@linux-foundation.org> - 2017-07-26 23:40 +0200
      Re: [PATCH] [v2] iopoll: avoid -Wint-in-bool-context warning Arnd Bergmann <arnd@arndb.de> - 2017-07-26 23:50 +0200

#1697096 — [PATCH] [v2] iopoll: avoid -Wint-in-bool-context warning

When we pass the result of a multiplication as the timeout or
the delay, we can get a warning:

drivers/mmc/host/bcm2835.c:596:149: error: '*' in boolean context, suggest '&&' instead [-Werror=int-in-bool-context]
drivers/mfd/arizona-core.c:247:195: error: '*' in boolean context, suggest '&&' instead [-Werror=int-in-bool-context]
drivers/gpu/drm/sun4i/sun4i_hdmi_i2c.c:49:27: error: '*' in boolean context, suggest '&&' instead [-Werror=int-in-bool-context]

The warning is a bit questionable inside of a macro, but this
is intentional on the side of the gcc developers. It is also
an indication of another problem: we evaluate the timeout
and sleep arguments multiple times, which can have undesired
side-effects when those are complex expressions.

This changes the three iopoll variants to use local variables
for storing copies of the timeouts. This adds some more type
safety, and avoids both the double-evaluation and the gcc
warning.

Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81484
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
v2: - use temporary variables instead of zero-comparison, to
      avoid double evaluation
    - also address the delay, not just timout handling
---
 include/linux/iopoll.h | 24 +++++++++++++++---------
 include/linux/regmap.h | 12 +++++++-----
 2 files changed, 22 insertions(+), 14 deletions(-)

diff --git a/include/linux/iopoll.h b/include/linux/iopoll.h
index d29e1e21bf3f..b1d861caca16 100644
--- a/include/linux/iopoll.h
+++ b/include/linux/iopoll.h
@@ -42,18 +42,21 @@
  */
 #define readx_poll_timeout(op, addr, val, cond, sleep_us, timeout_us)	\
 ({ \
-	ktime_t timeout = ktime_add_us(ktime_get(), timeout_us); \
-	might_sleep_if(sleep_us); \
+	u64 __timeout_us = (timeout_us); \
+	unsigned long __sleep_us = (sleep_us); \
+	ktime_t __timeout = ktime_add_us(ktime_get(), __timeout_us); \
+	might_sleep_if((__sleep_us) != 0); \
 	for (;;) { \
 		(val) = op(addr); \
 		if (cond) \
 			break; \
-		if (timeout_us && ktime_compare(ktime_get(), timeout) > 0) { \
+		if (__timeout_us && \
+		    ktime_compare(ktime_get(), __timeout) > 0) { \
 			(val) = op(addr); \
 			break; \
 		} \
-		if (sleep_us) \
-			usleep_range((sleep_us >> 2) + 1, sleep_us); \
+		if (__sleep_us) \
+			usleep_range((__sleep_us >> 2) + 1, __sleep_us); \
 	} \
 	(cond) ? 0 : -ETIMEDOUT; \
 })
@@ -77,17 +80,20 @@
  */
 #define readx_poll_timeout_atomic(op, addr, val, cond, delay_us, timeout_us) \
 ({ \
-	ktime_t timeout = ktime_add_us(ktime_get(), timeout_us); \
+	u64 __timeout_us = (timeout_us); \
+	unsigned long __delay_us = (delay_us); \
+	ktime_t __timeout = ktime_add_us(ktime_get(), __timeout_us); \
 	for (;;) { \
 		(val) = op(addr); \
 		if (cond) \
 			break; \
-		if (timeout_us && ktime_compare(ktime_get(), timeout) > 0) { \
+		if (__timeout_us && \
+		    ktime_compare(ktime_get(), __timeout) > 0) { \
 			(val) = op(addr); \
 			break; \
 		} \
-		if (delay_us) \
-			udelay(delay_us);	\
+		if (__delay_us) \
+			udelay(__delay_us);	\
 	} \
 	(cond) ? 0 : -ETIMEDOUT; \
 })
diff --git a/include/linux/regmap.h b/include/linux/regmap.h
index 1474ab0a3922..a4d30c877f6b 100644
--- a/include/linux/regmap.h
+++ b/include/linux/regmap.h
@@ -120,22 +120,24 @@ struct reg_sequence {
  */
 #define regmap_read_poll_timeout(map, addr, val, cond, sleep_us, timeout_us) \
 ({ \
-	ktime_t __timeout = ktime_add_us(ktime_get(), timeout_us); \
+	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); \
+	might_sleep_if(__sleep_us); \
 	for (;;) { \
 		__ret = regmap_read((map), (addr), &(val)); \
 		if (__ret) \
 			break; \
 		if (cond) \
 			break; \
-		if ((timeout_us) && \
+		if (__timeout_us && \
 		    ktime_compare(ktime_get(), __timeout) > 0) { \
 			__ret = regmap_read((map), (addr), &(val)); \
 			break; \
 		} \
-		if (sleep_us) \
-			usleep_range(((sleep_us) >> 2) + 1, sleep_us); \
+		if (__sleep_us) \
+			usleep_range((__sleep_us >> 2) + 1, __sleep_us); \
 	} \
 	__ret ?: ((cond) ? 0 : -ETIMEDOUT); \
 })
-- 
2.9.0

[toc] | [next] | [standalone]

#1697212

[Multipart message — attachments visible in raw view] — view raw

On Wed, Jul 26, 2017 at 03:37:32PM +0200, Arnd Bergmann wrote:
> When we pass the result of a multiplication as the timeout or
> the delay, we can get a warning:

This'd be easier if you sent each of the changes separately...

>  include/linux/iopoll.h | 24 +++++++++++++++---------
>  include/linux/regmap.h | 12 +++++++-----
>  2 files changed, 22 insertions(+), 14 deletions(-)

[toc] | [prev] | [next] | [standalone]

#1697575

On Wed, 26 Jul 2017 15:28:06 +0100 Mark Brown <broonie@kernel.org> wrote:

> On Wed, Jul 26, 2017 at 03:37:32PM +0200, Arnd Bergmann wrote:
> > When we pass the result of a multiplication as the timeout or
> > the delay, we can get a warning:
> 
> This'd be easier if you sent each of the changes separately...

I think it's OK - the patch encapsulates a single concept.  Doesn't
matter much either way, unless someone wants to take one part only into
a particular tree(?).

[toc] | [prev] | [next] | [standalone]

#1697851

[Multipart message — attachments visible in raw view] — view raw

On Wed, Jul 26, 2017 at 02:39:11PM -0700, Andrew Morton wrote:
> On Wed, 26 Jul 2017 15:28:06 +0100 Mark Brown <broonie@kernel.org> wrote:

> > On Wed, Jul 26, 2017 at 03:37:32PM +0200, Arnd Bergmann wrote:
> > > When we pass the result of a multiplication as the timeout or
> > > the delay, we can get a warning:

> > This'd be easier if you sent each of the changes separately...

> I think it's OK - the patch encapsulates a single concept.  Doesn't
> matter much either way, unless someone wants to take one part only into
> a particular tree(?).

I'd have applied the regmap bit if it weren't wrapped up with the iopoll
change.

[toc] | [prev] | [next] | [standalone]

#1697578

On Wed, 26 Jul 2017 15:37:32 +0200 Arnd Bergmann <arnd@arndb.de> wrote:

> When we pass the result of a multiplication as the timeout or
> the delay, we can get a warning:

from?  gcc-7 I assume?

[toc] | [prev] | [next] | [standalone]

#1697580

On Wed, Jul 26, 2017 at 11:38 PM, Andrew Morton
<akpm@linux-foundation.org> wrote:
> On Wed, 26 Jul 2017 15:37:32 +0200 Arnd Bergmann <arnd@arndb.de> wrote:
>
>> When we pass the result of a multiplication as the timeout or
>> the delay, we can get a warning:
>
> from?  gcc-7 I assume?

Correct, sorry for missing this. In fact, the warning is currently disabled
on mainline kernels, but there are only a couple of instance remaining,
so I expect to be able to turn it back on in the future.

       Arnd

[toc] | [prev] | [standalone]

Back to top | Article view | linux.kernel

csiph-web