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authorGustavo A. R. Silva <gustavoars@kernel.org>2020-05-07 21:53:13 +0300
committerJohan Hovold <johan@kernel.org>2020-05-13 18:30:31 +0300
commit9b5816b56af6a424619ab51d24de34dfc65102d8 (patch)
tree3354a5a71ff0505f8ab6c2f925a4d05225360bba /drivers/gnss/serial.h
parent43d7ce70ae43dd8523754b17f567417e0e75dbce (diff)
downloadlinux-9b5816b56af6a424619ab51d24de34dfc65102d8.tar.xz
gnss: 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> Signed-off-by: Johan Hovold <johan@kernel.org>
Diffstat (limited to 'drivers/gnss/serial.h')
-rw-r--r--drivers/gnss/serial.h2
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/gnss/serial.h b/drivers/gnss/serial.h
index 980ffdc86c2a..621953f7821d 100644
--- a/drivers/gnss/serial.h
+++ b/drivers/gnss/serial.h
@@ -16,7 +16,7 @@ struct gnss_serial {
struct gnss_device *gdev;
speed_t speed;
const struct gnss_serial_ops *ops;
- unsigned long drvdata[0];
+ unsigned long drvdata[];
};
enum gnss_serial_pm_state {