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authorGustavo A. R. Silva <gustavoars@kernel.org>2020-05-07 13:52:45 -0500
committerTakashi Iwai <tiwai@suse.de>2020-05-08 09:41:30 +0200
commit89ebe49aaa2f60a19db53b4c03fd25253ae7f4ec (patch)
tree9f01d643e42ce5c7133b39d1b6ea51fe5a9026f6 /sound/firewire
parent9ad06ebb9ad6ec4bb707f2a4a352ad6c382b5cd5 (diff)
downloadlinux-89ebe49aaa2f60a19db53b4c03fd25253ae7f4ec.tar.bz2
ALSA: fireworks: 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> Acked-by: Takashi Sakamoto <o-takashi@sakamocchi.jp> Link: https://lore.kernel.org/r/20200507185245.GA14270@embeddedor Signed-off-by: Takashi Iwai <tiwai@suse.de>
Diffstat (limited to 'sound/firewire')
-rw-r--r--sound/firewire/fireworks/fireworks.h2
1 files changed, 1 insertions, 1 deletions
diff --git a/sound/firewire/fireworks/fireworks.h b/sound/firewire/fireworks/fireworks.h
index dda797209a27..654e28a6669f 100644
--- a/sound/firewire/fireworks/fireworks.h
+++ b/sound/firewire/fireworks/fireworks.h
@@ -177,7 +177,7 @@ struct snd_efw_phys_meters {
u32 in_meters;
u32 reserved4;
u32 reserved5;
- u32 values[0];
+ u32 values[];
} __packed;
enum snd_efw_clock_source {
SND_EFW_CLOCK_SOURCE_INTERNAL = 0,