ath11k: Replace zero-length array with flexible-array
Subsystems (3)
PATCH 1/1 ath11k: 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")
--- drivers/net/wireless/ath/ath11k/debug.h | 4 ++-- drivers/net/wireless/ath/ath11k/debug_htt_stats.h | 8 ++++---- drivers/net/wireless/ath/ath11k/hal_desc.h | 4 ++-- drivers/net/wireless/ath/ath11k/hal_rx.h | 2 +- drivers/net/wireless/ath/ath11k/hw.h | 2 +- drivers/net/wireless/ath/ath11k/wmi.h | 2 +- 6 files changed, 11 insertions(+), 11 deletions(-)
drivers/net/wireless/ath/ath11k/debug.h +2 -2
@@ -67,7 +67,7 @@ struct debug_htt_stats_req {u8 peer_addr[ETH_ALEN ];struct completion cmpln;u32 buf_len; -u8 buf[0 ]; +u8 buf[]; };struct ath_pktlog_hdr {
@@ -77,7 +77,7 @@ struct ath_pktlog_hdr {u16 size;u32 timestamp;u32 type_specific_data; -u8 payload[0 ]; +u8 payload[]; };#define ATH11K_HTT_STATS_BUF_SIZE (1024 * 512)
drivers/net/wireless/ath/ath11k/debug_htt_stats.h +4 -4
@@ -239,7 +239,7 @@ struct htt_tx_pdev_stats_tx_ppdu_stats_tlv_v {*/ struct htt_tx_pdev_stats_tried_mpdu_cnt_hist_tlv_v {u32 hist_bin_size; -u32 tried_mpdu_cnt_hist[0 ];/* HTT_TX_PDEV_TRIED_MPDU_CNT_HIST */ +u32 tried_mpdu_cnt_hist[];/* HTT_TX_PDEV_TRIED_MPDU_CNT_HIST */ };/* == SOC ERROR STATS == */
@@ -550,7 +550,7 @@ struct htt_tx_hwq_stats_cmn_tlv {struct htt_tx_hwq_difs_latency_stats_tlv_v {u32 hist_intvl;/* histogram of ppdu post to hwsch - > cmd status received */ -u32 difs_latency_hist[0 ];/* HTT_TX_HWQ_MAX_DIFS_LATENCY_BINS */ +u32 difs_latency_hist[];/* HTT_TX_HWQ_MAX_DIFS_LATENCY_BINS */ };/* NOTE: Variable length TLV, use length spec to infer array size */
@@ -586,7 +586,7 @@ struct htt_tx_hwq_fes_result_stats_tlv_v {struct htt_tx_hwq_tried_mpdu_cnt_hist_tlv_v {u32 hist_bin_size;/* Histogram of number of mpdus on tried mpdu */ -u32 tried_mpdu_cnt_hist[0 ];/* HTT_TX_HWQ_TRIED_MPDU_CNT_HIST */ +u32 tried_mpdu_cnt_hist[];/* HTT_TX_HWQ_TRIED_MPDU_CNT_HIST */ };/* NOTE: Variable length TLV, use length spec to infer array size
@@ -1584,7 +1584,7 @@ struct htt_pdev_stats_twt_session_tlv {struct htt_pdev_stats_twt_sessions_tlv {u32 pdev_id;u32 num_sessions; -struct htt_pdev_stats_twt_session_tlv twt_session[0 ]; +struct htt_pdev_stats_twt_session_tlv twt_session[]; };enum htt_rx_reo_resource_sample_id_enum {
drivers/net/wireless/ath/ath11k/hal_desc.h +2 -2
@@ -477,7 +477,7 @@ enum hal_tlv_tag {struct hal_tlv_hdr {u32 tl; -u8 value[0 ]; +u8 value[]; } __packed;#define RX_MPDU_DESC_INFO0_MSDU_COUNT GENMASK(7, 0)
@@ -1972,7 +1972,7 @@ struct hal_rx_reo_queue {u32 processed_total_bytes;u32 info5;u32 rsvd[3 ]; -struct hal_rx_reo_queue_ext ext_desc[0 ]; +struct hal_rx_reo_queue_ext ext_desc[]; } __packed;/* hal_rx_reo_queue
drivers/net/wireless/ath/ath11k/hal_rx.h +1 -1
@@ -23,7 +23,7 @@ struct hal_rx_wbm_rel_info {struct hal_rx_mon_status_tlv_hdr {u32 hdr; -u8 value[0 ]; +u8 value[]; };enum hal_rx_su_mu_coding {
drivers/net/wireless/ath/ath11k/hw.h +1 -1
@@ -111,7 +111,7 @@ struct ath11k_hw_params {struct ath11k_fw_ie {__le32 id;__le32 len; -u8 data[0 ]; +u8 data[]; };enum ath11k_bd_ie_board_type {
drivers/net/wireless/ath/ath11k/wmi.h +1 -1
@@ -39,7 +39,7 @@ struct wmi_cmd_hdr {struct wmi_tlv {u32 header; -u8 value[0 ]; +u8 value[]; } __packed;#define WMI_TLV_LEN GENMASK(15, 0)
Signature · 7 lines
2.26.2 _______________________________________________ ath11k mailing list [email protected] http://lists.infradead.org/mailman/listinfo/ath11k
Quoted 29 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]
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.
Quoted 8 lines
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] commit76497732932f("cxgb3/l2t: Fix undefined behaviour")Signed-off-by Gustavo A. R. Silva <[email protected]>Signed-off-by Kalle Valo <[email protected]>
Patch applied to ath-next branch of ath.git, thanks.
14dd3a71ccb7 ath11k: Replace zero-length array with flexible-array
Signature · 8 lines
https://patchwork.kernel.org/patch/11527611/ https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches _______________________________________________ ath11k mailing list [email protected] http://lists.infradead.org/mailman/listinfo/ath11k
Quoted 29 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]
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.
Quoted 8 lines
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] commit76497732932f("cxgb3/l2t: Fix undefined behaviour")Signed-off-by Gustavo A. R. Silva <[email protected]>Signed-off-by Kalle Valo <[email protected]>
Patch applied to ath-next branch of ath.git, thanks.
14dd3a71ccb7 ath11k: Replace zero-length array with flexible-array
Signature · 3 lines
https://patchwork.kernel.org/patch/11527611/ https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches