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authorGustavo A. R. Silva <gustavoars@kernel.org>2020-05-07 22:22:23 +0300
committerTakashi Iwai <tiwai@suse.de>2020-05-07 23:30:36 +0300
commit9ad06ebb9ad6ec4bb707f2a4a352ad6c382b5cd5 (patch)
treef5a18757567fc24fd39b398bb7b039230e6af990
parentdf1fceacb24853d79f41a1dd717b32ab08fa5f3f (diff)
downloadlinux-9ad06ebb9ad6ec4bb707f2a4a352ad6c382b5cd5.tar.xz
ALSA: Replace zero-length array with flexible-array
The current codebase makes use of the zero-length array language extension to the C90 standard, but the preferred mechanism to declare variable-length types such as these ones is a flexible array member[1][2], introduced in C99: struct foo { int stuff; struct boo array[]; }; By making use of the mechanism above, we will get a compiler warning in case the flexible array does not occur last in the structure, which will help us prevent some kind of undefined behavior bugs from being inadvertently introduced[3] to the codebase from now on. Also, notice that, dynamic memory allocations won't be affected by this change: "Flexible array members have incomplete type, and so the sizeof operator may not be applied. As a quirk of the original implementation of zero-length arrays, sizeof evaluates to zero."[1] sizeof(flexible-array-member) triggers a warning because flexible array members have incomplete type[1]. There are some instances of code in which the sizeof operator is being incorrectly/erroneously applied to zero-length arrays and the result is zero. Such instances may be hiding some bugs. So, this work (flexible-array member conversions) will also help to get completely rid of those sorts of issues. This issue was found with the help of Coccinelle. [1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html [2] https://github.com/KSPP/linux/issues/21 [3] commit 76497732932f ("cxgb3/l2t: Fix undefined behaviour") Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org> Link: https://lore.kernel.org/r/20200507192223.GA16335@embeddedor Signed-off-by: Takashi Iwai <tiwai@suse.de>
-rw-r--r--include/sound/control.h2
-rw-r--r--include/sound/intel-nhlt.h6
-rw-r--r--sound/core/oss/pcm_plugin.h2
-rw-r--r--sound/usb/usx2y/usbusx2y.h2
4 files changed, 6 insertions, 6 deletions
diff --git a/include/sound/control.h b/include/sound/control.h
index 11feeee31e35..aeaed2a05bae 100644
--- a/include/sound/control.h
+++ b/include/sound/control.h
@@ -75,7 +75,7 @@ struct snd_kcontrol {
unsigned long private_value;
void *private_data;
void (*private_free)(struct snd_kcontrol *kcontrol);
- struct snd_kcontrol_volatile vd[0]; /* volatile data */
+ struct snd_kcontrol_volatile vd[]; /* volatile data */
};
#define snd_kcontrol(n) list_entry(n, struct snd_kcontrol, list)
diff --git a/include/sound/intel-nhlt.h b/include/sound/intel-nhlt.h
index f657fd8fc0ad..743c2f442280 100644
--- a/include/sound/intel-nhlt.h
+++ b/include/sound/intel-nhlt.h
@@ -50,7 +50,7 @@ enum nhlt_device_type {
struct nhlt_specific_cfg {
u32 size;
- u8 caps[0];
+ u8 caps[];
} __packed;
struct nhlt_fmt_cfg {
@@ -60,7 +60,7 @@ struct nhlt_fmt_cfg {
struct nhlt_fmt {
u8 fmt_count;
- struct nhlt_fmt_cfg fmt_config[0];
+ struct nhlt_fmt_cfg fmt_config[];
} __packed;
struct nhlt_endpoint {
@@ -80,7 +80,7 @@ struct nhlt_endpoint {
struct nhlt_acpi_table {
struct acpi_table_header header;
u8 endpoint_count;
- struct nhlt_endpoint desc[0];
+ struct nhlt_endpoint desc[];
} __packed;
struct nhlt_resource_desc {
diff --git a/sound/core/oss/pcm_plugin.h b/sound/core/oss/pcm_plugin.h
index 8d2f7a4e3ab6..46e273bd4a78 100644
--- a/sound/core/oss/pcm_plugin.h
+++ b/sound/core/oss/pcm_plugin.h
@@ -64,7 +64,7 @@ struct snd_pcm_plugin {
char *buf;
snd_pcm_uframes_t buf_frames;
struct snd_pcm_plugin_channel *buf_channels;
- char extra_data[0];
+ char extra_data[];
};
int snd_pcm_plugin_build(struct snd_pcm_substream *handle,
diff --git a/sound/usb/usx2y/usbusx2y.h b/sound/usb/usx2y/usbusx2y.h
index e0f77172ce8f..144b85f57bd2 100644
--- a/sound/usb/usx2y/usbusx2y.h
+++ b/sound/usb/usx2y/usbusx2y.h
@@ -18,7 +18,7 @@ struct snd_usX2Y_AsyncSeq {
struct snd_usX2Y_urbSeq {
int submitted;
int len;
- struct urb *urb[0];
+ struct urb *urb[];
};
#include "usx2yhwdeppcm.h"