irqchip: irq-bcm7038-l1: Replace zero-length array with flexible-array member
Subsystems (4)
PATCH 1/1 irqchip: irq-bcm7038-l1: 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")
--- drivers/irqchip/irq-bcm7038-l1.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
drivers/irqchip/irq-bcm7038-l1.c +1 -1
@@ -50,7 +50,7 @@ struct bcm7038_l1_chip {struct bcm7038_l1_cpu {void __iomem *map_base; -u32 mask_cache[0 ]; +u32 mask_cache[]; };/*
Signature · 1 line
2.23.0
Quoted 25 lines · Gustavo A. R. Silva
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.
Quoted 8 lines
[1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
[2] https://github.com/KSPP/linux/issues/21
[3] commit76497732932f("cxgb3/l2t: Fix undefined behaviour")Signed-off-by Gustavo A. R. Silva <[email protected]>--- drivers/irqchip/irq-bcm7038-l1.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
Queued for 5.7.
Thanks,
M.
Signature · 1 line
Jazz is not dead, it just smells funny.
[tip: irq/core] irqchip/irq-bcm7038-l1: Replace zero-length array with flexible-array member
In reply to Gustavo A. R. SilvaThe following commit has been merged into the irq/core branch of tip:
The following commit has been merged into the irq/core branch of tip:
Commit-ID: b2e1cbfd2d4af6f0797ed259de5f48e7dde60014 Gitweb: https://git.kernel.org/tip/b2e1cbfd2d4af6f0797ed259de5f48e7dde60014 Author: Gustavo A. R. Silva <[email protected]> AuthorDate: Thu, 19 Mar 2020 16:44:38 -05:00 Committer: Marc Zyngier <[email protected]> CommitterDate: Sun, 22 Mar 2020 11:52:52
irqchip/irq-bcm7038-l1: 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")
--- drivers/irqchip/irq-bcm7038-l1.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
drivers/irqchip/irq-bcm7038-l1.c +1 -1
@@ -50,7 +50,7 @@ struct bcm7038_l1_chip {struct bcm7038_l1_cpu {void __iomem *map_base; -u32 mask_cache[0 ]; +u32 mask_cache[]; };/*