[PATCH net-next 2/2] ath10k: fix ath10k_pci struct layout

From: Arnd Bergmann
Date: Sat May 09 2020 - 08:07:47 EST


gcc-10 correctly points out a bug with a zero-length array in
struct ath10k_pci:

drivers/net/wireless/ath/ath10k/ahb.c: In function 'ath10k_ahb_remove':
drivers/net/wireless/ath/ath10k/ahb.c:30:9: error: array subscript 0 is outside the bounds of an interior zero-length array 'struct ath10k_ahb[0]' [-Werror=zero-length-bounds]
30 | return &((struct ath10k_pci *)ar->drv_priv)->ahb[0];
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In file included from drivers/net/wireless/ath/ath10k/ahb.c:13:
drivers/net/wireless/ath/ath10k/pci.h:185:20: note: while referencing 'ahb'
185 | struct ath10k_ahb ahb[0];
| ^~~

The last addition to the struct ignored the comments and added
new members behind the array that must remain last.

Change it to a flexible-array member and move it last again to
make it work correctly, prevent the same thing from happening
again (all compilers warn about flexible-array members in the
middle of a struct) and get it to build without warnings.

Fixes: 521fc37be3d8 ("ath10k: Avoid override CE5 configuration for QCA99X0 chipsets")
Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
---
drivers/net/wireless/ath/ath10k/pci.h | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/net/wireless/ath/ath10k/pci.h b/drivers/net/wireless/ath/ath10k/pci.h
index e3cbd259a2dc..862d0901c5b8 100644
--- a/drivers/net/wireless/ath/ath10k/pci.h
+++ b/drivers/net/wireless/ath/ath10k/pci.h
@@ -178,15 +178,16 @@ struct ath10k_pci {
*/
u32 (*targ_cpu_to_ce_addr)(struct ath10k *ar, u32 addr);

+ struct ce_attr *attr;
+ struct ce_pipe_config *pipe_config;
+ struct ce_service_to_pipe *serv_to_pipe;
+
/* Keep this entry in the last, memory for struct ath10k_ahb is
* allocated (ahb support enabled case) in the continuation of
* this struct.
*/
- struct ath10k_ahb ahb[0];
+ struct ath10k_ahb ahb[];

- struct ce_attr *attr;
- struct ce_pipe_config *pipe_config;
- struct ce_service_to_pipe *serv_to_pipe;
};

static inline struct ath10k_pci *ath10k_pci_priv(struct ath10k *ar)
--
2.26.0