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* [PATCH] ASoC: wcd934x: Remove some unnecessary NULL checks
@ 2020-02-04  6:01 Nathan Chancellor
  2020-02-04 10:00 ` Mark Brown
  2020-02-11 15:49 ` Applied "ASoC: wcd934x: Remove some unnecessary NULL checks" to the asoc tree Mark Brown
  0 siblings, 2 replies; 6+ messages in thread
From: Nathan Chancellor @ 2020-02-04  6:01 UTC (permalink / raw)
  To: Mark Brown, Liam Girdwood
  Cc: Srinivas Kandagatla, alsa-devel, linux-kernel, clang-built-linux,
	Nathan Chancellor

Clang warns:

../sound/soc/codecs/wcd934x.c:1886:11: warning: address of array
'wcd->rx_chs' will always evaluate to 'true' [-Wpointer-bool-conversion]
        if (wcd->rx_chs) {
        ~~  ~~~~~^~~~~~
../sound/soc/codecs/wcd934x.c:1894:11: warning: address of array
'wcd->tx_chs' will always evaluate to 'true' [-Wpointer-bool-conversion]
        if (wcd->tx_chs) {
        ~~  ~~~~~^~~~~~
2 warnings generated.

Arrays that are in the middle of a struct are never NULL so they don't
need a check like this.

Fixes: a61f3b4f476e ("ASoC: wcd934x: add support to wcd9340/wcd9341 codec")
Link: https://github.com/ClangBuiltLinux/linux/issues/854
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
---

Also, turns out this was fixed in the wcd9335 driver in
commit d22b4117538d ("ASoC: wcd9335: remove some unnecessary
NULL checks")...

 sound/soc/codecs/wcd934x.c | 20 ++++++++------------
 1 file changed, 8 insertions(+), 12 deletions(-)

diff --git a/sound/soc/codecs/wcd934x.c b/sound/soc/codecs/wcd934x.c
index 158e878abd6c..e780ecd554d2 100644
--- a/sound/soc/codecs/wcd934x.c
+++ b/sound/soc/codecs/wcd934x.c
@@ -1883,20 +1883,16 @@ static int wcd934x_set_channel_map(struct snd_soc_dai *dai,
 		return -EINVAL;
 	}
 
-	if (wcd->rx_chs) {
-		wcd->num_rx_port = rx_num;
-		for (i = 0; i < rx_num; i++) {
-			wcd->rx_chs[i].ch_num = rx_slot[i];
-			INIT_LIST_HEAD(&wcd->rx_chs[i].list);
-		}
+	wcd->num_rx_port = rx_num;
+	for (i = 0; i < rx_num; i++) {
+		wcd->rx_chs[i].ch_num = rx_slot[i];
+		INIT_LIST_HEAD(&wcd->rx_chs[i].list);
 	}
 
-	if (wcd->tx_chs) {
-		wcd->num_tx_port = tx_num;
-		for (i = 0; i < tx_num; i++) {
-			wcd->tx_chs[i].ch_num = tx_slot[i];
-			INIT_LIST_HEAD(&wcd->tx_chs[i].list);
-		}
+	wcd->num_tx_port = tx_num;
+	for (i = 0; i < tx_num; i++) {
+		wcd->tx_chs[i].ch_num = tx_slot[i];
+		INIT_LIST_HEAD(&wcd->tx_chs[i].list);
 	}
 
 	return 0;
-- 
2.25.0


^ permalink raw reply related	[flat|nested] 6+ messages in thread
* Re: [PATCH] ASoC: wcd934x: Remove some unnecessary NULL checks
  2020-02-04  6:01 [PATCH] ASoC: wcd934x: Remove some unnecessary NULL checks Nathan Chancellor
@ 2020-02-04 10:00 ` Mark Brown
  2020-02-04 19:32   ` Nathan Chancellor
  2020-02-11 15:49 ` Applied "ASoC: wcd934x: Remove some unnecessary NULL checks" to the asoc tree Mark Brown
  1 sibling, 1 reply; 6+ messages in thread
From: Mark Brown @ 2020-02-04 10:00 UTC (permalink / raw)
  To: Nathan Chancellor
  Cc: Liam Girdwood, Srinivas Kandagatla, alsa-devel, linux-kernel,
	clang-built-linux

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On Mon, Feb 03, 2020 at 11:01:44PM -0700, Nathan Chancellor wrote:
> Clang warns:
> 
> ../sound/soc/codecs/wcd934x.c:1886:11: warning: address of array
> 'wcd->rx_chs' will always evaluate to 'true' [-Wpointer-bool-conversion]
>         if (wcd->rx_chs) {
>         ~~  ~~~~~^~~~~~
> ../sound/soc/codecs/wcd934x.c:1894:11: warning: address of array
> 'wcd->tx_chs' will always evaluate to 'true' [-Wpointer-bool-conversion]
>         if (wcd->tx_chs) {
>         ~~  ~~~~~^~~~~~
> 2 warnings generated.
> 
> Arrays that are in the middle of a struct are never NULL so they don't
> need a check like this.

I'm not convincd this is a sensible warning, at the use site a
pointer to an array in a struct looks identical to an array
embedded in the struct so it's not such a bad idea to check and
refactoring of the struct could easily introduce problems.

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^ permalink raw reply	[flat|nested] 6+ messages in thread
* Re: [PATCH] ASoC: wcd934x: Remove some unnecessary NULL checks
  2020-02-04 10:00 ` Mark Brown
@ 2020-02-04 19:32   ` Nathan Chancellor
  2020-02-05 10:22     ` Mark Brown
  0 siblings, 1 reply; 6+ messages in thread
From: Nathan Chancellor @ 2020-02-04 19:32 UTC (permalink / raw)
  To: Mark Brown
  Cc: Liam Girdwood, Srinivas Kandagatla, alsa-devel, linux-kernel,
	clang-built-linux

On Tue, Feb 04, 2020 at 10:00:39AM +0000, Mark Brown wrote:
> On Mon, Feb 03, 2020 at 11:01:44PM -0700, Nathan Chancellor wrote:
> > Clang warns:
> > 
> > ../sound/soc/codecs/wcd934x.c:1886:11: warning: address of array
> > 'wcd->rx_chs' will always evaluate to 'true' [-Wpointer-bool-conversion]
> >         if (wcd->rx_chs) {
> >         ~~  ~~~~~^~~~~~
> > ../sound/soc/codecs/wcd934x.c:1894:11: warning: address of array
> > 'wcd->tx_chs' will always evaluate to 'true' [-Wpointer-bool-conversion]
> >         if (wcd->tx_chs) {
> >         ~~  ~~~~~^~~~~~
> > 2 warnings generated.
> > 
> > Arrays that are in the middle of a struct are never NULL so they don't
> > need a check like this.
> 
> I'm not convincd this is a sensible warning, at the use site a
> pointer to an array in a struct looks identical to an array
> embedded in the struct so it's not such a bad idea to check and
> refactoring of the struct could easily introduce problems.

There have been a few other bugs found with this warning:

9fcf2b3c1c02 ("drm/atmel-hlcdc: check stride values in the first plane")
44d7f1a77d8c ("media: pxa_camera: Fix check for pdev->dev.of_node")
8a72b81e6df5 ("isdn: isdnloop: fix pointer dereference bug")

Other static checkers like smatch will warn about this as well (since I
am sure that is how Dan Carpenter found the same issue in the wcd9335
driver). Isn't an antipattern in the kernel to do things "just in
case we do something later"? There are plenty of NULL checks removed
from the kernel because they do not do anything now.

I'd be fine with changing the check to something else that keeps the
same logic but doesn't create a warning; I am not exactly sure what that
would be because that is more of a specific driver logic thing, which I
am not familiar with.

Cheers,
Nathan

^ permalink raw reply	[flat|nested] 6+ messages in thread
* Re: [PATCH] ASoC: wcd934x: Remove some unnecessary NULL checks
  2020-02-04 19:32   ` Nathan Chancellor
@ 2020-02-05 10:22     ` Mark Brown
  2020-02-05 15:50       ` Nathan Chancellor
  0 siblings, 1 reply; 6+ messages in thread
From: Mark Brown @ 2020-02-05 10:22 UTC (permalink / raw)
  To: Nathan Chancellor
  Cc: Liam Girdwood, Srinivas Kandagatla, alsa-devel, linux-kernel,
	clang-built-linux

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On Tue, Feb 04, 2020 at 12:32:15PM -0700, Nathan Chancellor wrote:
> On Tue, Feb 04, 2020 at 10:00:39AM +0000, Mark Brown wrote:

> > I'm not convincd this is a sensible warning, at the use site a
> > pointer to an array in a struct looks identical to an array
> > embedded in the struct so it's not such a bad idea to check and
> > refactoring of the struct could easily introduce problems.

> Other static checkers like smatch will warn about this as well (since I
> am sure that is how Dan Carpenter found the same issue in the wcd9335
> driver). Isn't an antipattern in the kernel to do things "just in
> case we do something later"? There are plenty of NULL checks removed
> from the kernel because they do not do anything now.

I'm not convinced it is an antipattern - adding the checks would
be a bit silly but with the way C works the warnings feel like
false positives.  If the compiler were able to warn about missing
NULL checks in the case where the thing in the struct is a
pointer I'd be a lot happier with this.

> I'd be fine with changing the check to something else that keeps the
> same logic but doesn't create a warning; I am not exactly sure what that
> would be because that is more of a specific driver logic thing, which I
> am not familiar with.

I've queued the change to be applied since it's shuts the
compiler up but I'm really not convinced the compiler is helping
here.

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^ permalink raw reply	[flat|nested] 6+ messages in thread
* Re: [PATCH] ASoC: wcd934x: Remove some unnecessary NULL checks
  2020-02-05 10:22     ` Mark Brown
@ 2020-02-05 15:50       ` Nathan Chancellor
  0 siblings, 0 replies; 6+ messages in thread
From: Nathan Chancellor @ 2020-02-05 15:50 UTC (permalink / raw)
  To: Mark Brown
  Cc: Liam Girdwood, Srinivas Kandagatla, alsa-devel, linux-kernel,
	clang-built-linux

On Wed, Feb 05, 2020 at 10:22:38AM +0000, Mark Brown wrote:
> On Tue, Feb 04, 2020 at 12:32:15PM -0700, Nathan Chancellor wrote:
> > On Tue, Feb 04, 2020 at 10:00:39AM +0000, Mark Brown wrote:
> 
> > > I'm not convincd this is a sensible warning, at the use site a
> > > pointer to an array in a struct looks identical to an array
> > > embedded in the struct so it's not such a bad idea to check and
> > > refactoring of the struct could easily introduce problems.
> 
> > Other static checkers like smatch will warn about this as well (since I
> > am sure that is how Dan Carpenter found the same issue in the wcd9335
> > driver). Isn't an antipattern in the kernel to do things "just in
> > case we do something later"? There are plenty of NULL checks removed
> > from the kernel because they do not do anything now.
> 
> I'm not convinced it is an antipattern - adding the checks would
> be a bit silly but with the way C works the warnings feel like
> false positives.  If the compiler were able to warn about missing
> NULL checks in the case where the thing in the struct is a
> pointer I'd be a lot happier with this.

Yes, that would definitely be nice. I am not entirely sure that this is
possible with clang due to its architecture but I am far from a clang
internal expert.

> > I'd be fine with changing the check to something else that keeps the
> > same logic but doesn't create a warning; I am not exactly sure what that
> > would be because that is more of a specific driver logic thing, which I
> > am not familiar with.
> 
> I've queued the change to be applied since it's shuts the
> compiler up but I'm really not convinced the compiler is helping
> here.

Thank you :)

Cheers,
Nathan

^ permalink raw reply	[flat|nested] 6+ messages in thread
* Applied "ASoC: wcd934x: Remove some unnecessary NULL checks" to the asoc tree
  2020-02-04  6:01 [PATCH] ASoC: wcd934x: Remove some unnecessary NULL checks Nathan Chancellor
  2020-02-04 10:00 ` Mark Brown
@ 2020-02-11 15:49 ` Mark Brown
  1 sibling, 0 replies; 6+ messages in thread
From: Mark Brown @ 2020-02-11 15:49 UTC (permalink / raw)
  To: Nathan Chancellor
  Cc: alsa-devel, clang-built-linux, Liam Girdwood, linux-kernel,
	Mark Brown, Srinivas Kandagatla

The patch

   ASoC: wcd934x: Remove some unnecessary NULL checks

has been applied to the asoc tree at

   https://git.kernel.org/pub/scm/linux/kernel/git/broonie/sound.git for-5.7

All being well this means that it will be integrated into the linux-next
tree (usually sometime in the next 24 hours) and sent to Linus during
the next merge window (or sooner if it is a bug fix), however if
problems are discovered then the patch may be dropped or reverted.  

You may get further e-mails resulting from automated or manual testing
and review of the tree, please engage with people reporting problems and
send followup patches addressing any issues that are reported if needed.

If any updates are required or you are submitting further changes they
should be sent as incremental updates against current git, existing
patches will not be replaced.

Please add any relevant lists and maintainers to the CCs when replying
to this mail.

Thanks,
Mark

From 918d0aba86ed8c1f4ff7f39e39e5c1b46fff2bc2 Mon Sep 17 00:00:00 2001
From: Nathan Chancellor <natechancellor@gmail.com>
Date: Mon, 3 Feb 2020 23:01:44 -0700
Subject: [PATCH] ASoC: wcd934x: Remove some unnecessary NULL checks

Clang warns:

../sound/soc/codecs/wcd934x.c:1886:11: warning: address of array
'wcd->rx_chs' will always evaluate to 'true' [-Wpointer-bool-conversion]
        if (wcd->rx_chs) {
        ~~  ~~~~~^~~~~~
../sound/soc/codecs/wcd934x.c:1894:11: warning: address of array
'wcd->tx_chs' will always evaluate to 'true' [-Wpointer-bool-conversion]
        if (wcd->tx_chs) {
        ~~  ~~~~~^~~~~~
2 warnings generated.

Arrays that are in the middle of a struct are never NULL so they don't
need a check like this.

Fixes: a61f3b4f476e ("ASoC: wcd934x: add support to wcd9340/wcd9341 codec")
Link: https://github.com/ClangBuiltLinux/linux/issues/854
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
Link: https://lore.kernel.org/r/20200204060143.23393-1-natechancellor@gmail.com
Signed-off-by: Mark Brown <broonie@kernel.org>
---
 sound/soc/codecs/wcd934x.c | 20 ++++++++------------
 1 file changed, 8 insertions(+), 12 deletions(-)

diff --git a/sound/soc/codecs/wcd934x.c b/sound/soc/codecs/wcd934x.c
index 158e878abd6c..e780ecd554d2 100644
--- a/sound/soc/codecs/wcd934x.c
+++ b/sound/soc/codecs/wcd934x.c
@@ -1883,20 +1883,16 @@ static int wcd934x_set_channel_map(struct snd_soc_dai *dai,
 		return -EINVAL;
 	}
 
-	if (wcd->rx_chs) {
-		wcd->num_rx_port = rx_num;
-		for (i = 0; i < rx_num; i++) {
-			wcd->rx_chs[i].ch_num = rx_slot[i];
-			INIT_LIST_HEAD(&wcd->rx_chs[i].list);
-		}
+	wcd->num_rx_port = rx_num;
+	for (i = 0; i < rx_num; i++) {
+		wcd->rx_chs[i].ch_num = rx_slot[i];
+		INIT_LIST_HEAD(&wcd->rx_chs[i].list);
 	}
 
-	if (wcd->tx_chs) {
-		wcd->num_tx_port = tx_num;
-		for (i = 0; i < tx_num; i++) {
-			wcd->tx_chs[i].ch_num = tx_slot[i];
-			INIT_LIST_HEAD(&wcd->tx_chs[i].list);
-		}
+	wcd->num_tx_port = tx_num;
+	for (i = 0; i < tx_num; i++) {
+		wcd->tx_chs[i].ch_num = tx_slot[i];
+		INIT_LIST_HEAD(&wcd->tx_chs[i].list);
 	}
 
 	return 0;
-- 
2.20.1


^ permalink raw reply related	[flat|nested] 6+ messages in thread
end of thread, other threads:[~2020-02-11 15:49 UTC | newest]

Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
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2020-02-04  6:01 [PATCH] ASoC: wcd934x: Remove some unnecessary NULL checks Nathan Chancellor
2020-02-04 10:00 ` Mark Brown
2020-02-04 19:32   ` Nathan Chancellor
2020-02-05 10:22     ` Mark Brown
2020-02-05 15:50       ` Nathan Chancellor
2020-02-11 15:49 ` Applied "ASoC: wcd934x: Remove some unnecessary NULL checks" to the asoc tree Mark Brown

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