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authorGustavo A. R. Silva <gustavo@embeddedor.com>2020-02-12 22:52:31 +0300
committerMiguel Ojeda <miguel.ojeda.sandonis@gmail.com>2020-03-07 00:18:07 +0300
commit2f920c0f0e29268827c2894c6e8f237a78159718 (patch)
treed207a6fd49dda02b7eb1e9a3e97bdfa15bf49d4f /drivers/auxdisplay
parente8897e4fe8f27d407b1e00ee0410fd3ec396275c (diff)
downloadlinux-2f920c0f0e29268827c2894c6e8f237a78159718.tar.xz
auxdisplay: charlcd: replace zero-length array with flexible-array member
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] 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 <gustavo@embeddedor.com> Signed-off-by: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>
Diffstat (limited to 'drivers/auxdisplay')
-rw-r--r--drivers/auxdisplay/charlcd.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/auxdisplay/charlcd.c b/drivers/auxdisplay/charlcd.c
index 874c259a8829..c0da3820454b 100644
--- a/drivers/auxdisplay/charlcd.c
+++ b/drivers/auxdisplay/charlcd.c
@@ -88,7 +88,7 @@ struct charlcd_priv {
int len;
} esc_seq;
- unsigned long long drvdata[0];
+ unsigned long long drvdata[];
};
#define charlcd_to_priv(p) container_of(p, struct charlcd_priv, lcd)