Re: [PATCH 15/23] net: Avoid dynamic stack allocation

[Jason Wang]

在 2021/5/6 上午5:10, Philippe Mathieu-Daudé 写道:
> Use autofree heap allocation instead of variable-length
> array on the stack.
>
> Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>


Acked-by: Jason Wang <jasowang@redhat.com>


> ---
>   hw/net/fsl_etsec/rings.c      | 9 ++++-----
>   hw/net/rocker/rocker_of_dpa.c | 2 +-
>   net/dump.c                    | 2 +-
>   net/tap.c                     | 2 +-
>   4 files changed, 7 insertions(+), 8 deletions(-)
>
> diff --git a/hw/net/fsl_etsec/rings.c b/hw/net/fsl_etsec/rings.c
> index 8f084464155..1abdcb5a29c 100644
> --- a/hw/net/fsl_etsec/rings.c
> +++ b/hw/net/fsl_etsec/rings.c
> @@ -381,8 +381,6 @@ static void fill_rx_bd(eTSEC          *etsec,
>       uint16_t to_write;
>       hwaddr   bufptr = bd->bufptr +
>           ((hwaddr)(etsec->regs[TBDBPH].value & 0xF) << 32);
> -    uint8_t  padd[etsec->rx_padding];
> -    uint8_t  rem;
>   
>       RING_DEBUG("eTSEC fill Rx buffer @ 0x%016" HWADDR_PRIx
>                  " size:%zu(padding + crc:%u) + fcb:%u\n",
> @@ -423,11 +421,12 @@ static void fill_rx_bd(eTSEC          *etsec,
>           /* The remaining bytes are only for padding which is not actually
>            * allocated in the data buffer.
>            */
> -
> -        rem = MIN(etsec->regs[MRBLR].value - bd->length, etsec->rx_padding);
> +        uint8_t  rem = MIN(etsec->regs[MRBLR].value - bd->length,
> +                           etsec->rx_padding);
>   
>           if (rem > 0) {
> -            memset(padd, 0x0, sizeof(padd));
> +            g_autofree uint8_t *padd = g_malloc0(etsec->rx_padding);
> +
>               etsec->rx_padding -= rem;
>               *size             -= rem;
>               bd->length        += rem;
> diff --git a/hw/net/rocker/rocker_of_dpa.c b/hw/net/rocker/rocker_of_dpa.c
> index b3b8c5bb6d4..3e400ceaef7 100644
> --- a/hw/net/rocker/rocker_of_dpa.c
> +++ b/hw/net/rocker/rocker_of_dpa.c
> @@ -1043,7 +1043,7 @@ static void of_dpa_flow_ig_tbl(OfDpaFlowContext *fc, 
> uint32_t tbl_id)
>   static ssize_t of_dpa_ig(World *world, uint32_t pport,
>                            const struct iovec *iov, int iovcnt)
>   {
> -    struct iovec iov_copy[iovcnt + 2];
> +    g_autofree struct iovec *iov_copy = g_new(struct iovec, iovcnt + 2);
>       OfDpaFlowContext fc = {
>           .of_dpa = world_private(world),
>           .in_pport = pport,
> diff --git a/net/dump.c b/net/dump.c
> index 4d538d82a69..b830302e27d 100644
> --- a/net/dump.c
> +++ b/net/dump.c
> @@ -68,7 +68,7 @@ static ssize_t dump_receive_iov(DumpState *s, const struct 
> iovec *iov, int cnt)
>       int64_t ts;
>       int caplen;
>       size_t size = iov_size(iov, cnt);
> -    struct iovec dumpiov[cnt + 1];
> +    g_autofree struct iovec *dumpiov = g_new(struct iovec, cnt + 1);
>   
>       /* Early return in case of previous error. */
>       if (s->fd < 0) {
> diff --git a/net/tap.c b/net/tap.c
> index bae895e2874..2b9ed8a2cd8 100644
> --- a/net/tap.c
> +++ b/net/tap.c
> @@ -120,7 +120,7 @@ static ssize_t tap_receive_iov(NetClientState *nc, const 
> struct iovec *iov,
>   {
>       TAPState *s = DO_UPCAST(TAPState, nc, nc);
>       const struct iovec *iovp = iov;
> -    struct iovec iov_copy[iovcnt + 1];
> +    g_autofree struct iovec *iov_copy = g_new(struct iovec, iovcnt + 1);
>       struct virtio_net_hdr_mrg_rxbuf hdr = { };
>   
>       if (s->host_vnet_hdr_len && !s->using_vnet_hdr) {