| Message ID | 20200212235911.GA20179@embeddedor.com (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | 7235d9e48fda6902018e04669eda6f5d1878599f |
| Headers | show |
| Series | mfd: pm8xxx: Replace zero-length array with flexible-array member | expand |
diff --git a/drivers/mfd/qcom-pm8xxx.c b/drivers/mfd/qcom-pm8xxx.c index 29133326c6fd..acd172ddcbd6 100644 --- a/drivers/mfd/qcom-pm8xxx.c +++ b/drivers/mfd/qcom-pm8xxx.c @@ -76,7 +76,7 @@ struct pm_irq_chip { unsigned int num_masters; const struct pm_irq_data *pm_irq_data; /* MUST BE AT THE END OF THIS STRUCT */ - u8 config[0]; + u8 config[]; }; static int pm8xxx_read_block_irq(struct pm_irq_chip *chip, unsigned int bp,
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> --- drivers/mfd/qcom-pm8xxx.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)