[PATCH] ath11k: Replace one-element array with flexible-array member

There is a regular need in the kernel to provide a way to declare having
a dynamically sized set of trailing elements in a structure. Kernel code
should always use "flexible array members"[1] for these cases. The older
style of one-element or zero-length arrays should no longer be used[2].

Also, refactor the code a bit to make use of the struct_size() helper in
kzalloc().

[1] https://en.wikipedia.org/wiki/Flexible_array_member
[2] https://www.kernel.org/doc/html/v5.14/process/deprecated.html#zero-length-and-one-element-arrays

Signed-off-by: Len Baker <redacted>
---
 drivers/net/wireless/ath/ath11k/reg.c | 7 ++-----
 drivers/net/wireless/ath/ath11k/wmi.h | 2 +-
 2 files changed, 3 insertions(+), 6 deletions(-)

diff --git a/drivers/net/wireless/ath/ath11k/reg.c b/drivers/net/wireless/ath/ath11k/reg.c
index e1a1df169034..c83d265185f1 100644
--- a/drivers/net/wireless/ath/ath11k/reg.c
+++ b/drivers/net/wireless/ath/ath11k/reg.c

@@ -97,7 +97,6 @@ int ath11k_reg_update_chan_list(struct ath11k *ar)
 	struct channel_param *ch;
 	enum nl80211_band band;
 	int num_channels = 0;
-	int params_len;
 	int i, ret;

 	bands = hw->wiphy->bands;

@@ -117,10 +116,8 @@ int ath11k_reg_update_chan_list(struct ath11k *ar)
 	if (WARN_ON(!num_channels))
 		return -EINVAL;

-	params_len = sizeof(struct scan_chan_list_params) +
-			num_channels * sizeof(struct channel_param);
-	params = kzalloc(params_len, GFP_KERNEL);
-
+	params = kzalloc(struct_size(params, ch_param, num_channels),
+			 GFP_KERNEL);
 	if (!params)
 		return -ENOMEM;

diff --git a/drivers/net/wireless/ath/ath11k/wmi.h b/drivers/net/wireless/ath/ath11k/wmi.h
index d35c47e0b19d..d9c83726f65d 100644
--- a/drivers/net/wireless/ath/ath11k/wmi.h
+++ b/drivers/net/wireless/ath/ath11k/wmi.h

@@ -3608,7 +3608,7 @@ struct wmi_stop_scan_cmd {
 struct scan_chan_list_params {
 	u32 pdev_id;
 	u16 nallchans;
-	struct channel_param ch_param[1];
+	struct channel_param ch_param[];
 };

 struct wmi_scan_chan_list_cmd {
--

2.25.1

There is already a patch for this:

https://lore.kernel.org/lkml/20210823172159.GA25800@embeddedor/

which I will now add to my -next tree.

Thanks
--
Gustavo

On Sat, Sep 04, 2021 at 01:49:37PM +0200, Len Baker wrote:

On 9/12/21 14:31, Gustavo A. R. Silva wrote:

There is already a patch for this:

https://lore.kernel.org/lkml/20210823172159.GA25800@embeddedor/

which I will now add to my -next tree.

Well, in this case I think it's much better if Kalle can take it. :)

--
Gustavo

On Sat, Sep 04, 2021 at 01:49:37PM +0200, Len Baker wrote:

quoted

There is a regular need in the kernel to provide a way to declare having
a dynamically sized set of trailing elements in a structure. Kernel code
should always use "flexible array members"[1] for these cases. The older
style of one-element or zero-length arrays should no longer be used[2].

Also, refactor the code a bit to make use of the struct_size() helper in
kzalloc().

[1] https://en.wikipedia.org/wiki/Flexible_array_member
[2] https://www.kernel.org/doc/html/v5.14/process/deprecated.html#zero-length-and-one-element-arrays

Signed-off-by: Len Baker <redacted>
---
 drivers/net/wireless/ath/ath11k/reg.c | 7 ++-----
 drivers/net/wireless/ath/ath11k/wmi.h | 2 +-
 2 files changed, 3 insertions(+), 6 deletions(-)

diff --git a/drivers/net/wireless/ath/ath11k/reg.c b/drivers/net/wireless/ath/ath11k/reg.c
index e1a1df169034..c83d265185f1 100644
--- a/drivers/net/wireless/ath/ath11k/reg.c
+++ b/drivers/net/wireless/ath/ath11k/reg.c

@@ -97,7 +97,6 @@ int ath11k_reg_update_chan_list(struct ath11k *ar)
 	struct channel_param *ch;
 	enum nl80211_band band;
 	int num_channels = 0;
-	int params_len;
 	int i, ret;

 	bands = hw->wiphy->bands;

@@ -117,10 +116,8 @@ int ath11k_reg_update_chan_list(struct ath11k *ar)
 	if (WARN_ON(!num_channels))
 		return -EINVAL;

-	params_len = sizeof(struct scan_chan_list_params) +
-			num_channels * sizeof(struct channel_param);
-	params = kzalloc(params_len, GFP_KERNEL);
-
+	params = kzalloc(struct_size(params, ch_param, num_channels),
+			 GFP_KERNEL);
 	if (!params)
 		return -ENOMEM;

diff --git a/drivers/net/wireless/ath/ath11k/wmi.h b/drivers/net/wireless/ath/ath11k/wmi.h
index d35c47e0b19d..d9c83726f65d 100644
--- a/drivers/net/wireless/ath/ath11k/wmi.h
+++ b/drivers/net/wireless/ath/ath11k/wmi.h

@@ -3608,7 +3608,7 @@ struct wmi_stop_scan_cmd {
 struct scan_chan_list_params {
 	u32 pdev_id;
 	u16 nallchans;
-	struct channel_param ch_param[1];
+	struct channel_param ch_param[];
 };

 struct wmi_scan_chan_list_cmd {
--

2.25.1