Re: [PATCH v1] Bluetooth: Optimize devcoredump API hci_devcd_init()

From: Luiz Augusto von Dentz
Date: Fri Apr 14 2023 - 17:03:44 EST


Hi Zijun,

On Tue, Apr 11, 2023 at 4:49 AM Zijun Hu <quic_zijuhu@xxxxxxxxxxx> wrote:
>
> API hci_devcd_init() stores u32 type to memory without specific byte
> order, let us store with little endian in order to be loaded and
> parsed by devcoredump core rightly.

This looks like a fix if devcoredump expects little endian, so I'd
suggest rephrasing to state it in the subject line, also add the Fixes
tag for the commit that introduces this problem.

> Signed-off-by: Zijun Hu <quic_zijuhu@xxxxxxxxxxx>
> ---
> net/bluetooth/coredump.c | 13 +++++++------
> 1 file changed, 7 insertions(+), 6 deletions(-)
>
> diff --git a/net/bluetooth/coredump.c b/net/bluetooth/coredump.c
> index 08fa98505454..d2d2624ec708 100644
> --- a/net/bluetooth/coredump.c
> +++ b/net/bluetooth/coredump.c
> @@ -5,6 +5,7 @@
>
> #include <linux/devcoredump.h>
>
> +#include <asm/unaligned.h>
> #include <net/bluetooth/bluetooth.h>
> #include <net/bluetooth/hci_core.h>
>
> @@ -180,25 +181,25 @@ static int hci_devcd_prepare(struct hci_dev *hdev, u32 dump_size)
>
> static void hci_devcd_handle_pkt_init(struct hci_dev *hdev, struct sk_buff *skb)
> {
> - u32 *dump_size;
> + u32 dump_size;
>
> if (hdev->dump.state != HCI_DEVCOREDUMP_IDLE) {
> DBG_UNEXPECTED_STATE();
> return;
> }
>
> - if (skb->len != sizeof(*dump_size)) {
> + if (skb->len != sizeof(dump_size)) {
> bt_dev_dbg(hdev, "Invalid dump init pkt");
> return;
> }
>
> - dump_size = skb_pull_data(skb, sizeof(*dump_size));
> - if (!*dump_size) {
> + dump_size = get_unaligned_le32(skb_pull_data(skb, 4));
> + if (!dump_size) {
> bt_dev_err(hdev, "Zero size dump init pkt");
> return;
> }
>
> - if (hci_devcd_prepare(hdev, *dump_size)) {
> + if (hci_devcd_prepare(hdev, dump_size)) {
> bt_dev_err(hdev, "Failed to prepare for dump");
> return;
> }
> @@ -441,7 +442,7 @@ int hci_devcd_init(struct hci_dev *hdev, u32 dump_size)
> return -ENOMEM;
>
> hci_dmp_cb(skb)->pkt_type = HCI_DEVCOREDUMP_PKT_INIT;
> - skb_put_data(skb, &dump_size, sizeof(dump_size));
> + put_unaligned_le32(dump_size, skb_put(skb, 4));
>
> skb_queue_tail(&hdev->dump.dump_q, skb);
> queue_work(hdev->workqueue, &hdev->dump.dump_rx);
> --
> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project
>


--
Luiz Augusto von Dentz