Re: [Qemu-devel] [PATCH 1/2 v2] usb-mtp: Reallocate buffer in multiples of MTP_WRITE_BUF_SZ

[Eric Blake]

On 1/11/19 2:20 AM, Bandan Das wrote:
> This is a "pre-patch" to breaking up the write buffer for
> MTP writes. Instead of allocating a mtp buffer equal to size
> sent by the initiator, we start with a small size and reallocate
> multiples (of that small size) as needed.
> 
> Signed-off-by: Bandan Das <b...@redhat.com>
> ---
>  hw/usb/dev-mtp.c | 26 ++++++++++++--------------
>  1 file changed, 12 insertions(+), 14 deletions(-)
> 
> diff --git a/hw/usb/dev-mtp.c b/hw/usb/dev-mtp.c
> index b19b576278..a0d98c93ee 100644
> --- a/hw/usb/dev-mtp.c
> +++ b/hw/usb/dev-mtp.c
> @@ -152,7 +152,6 @@ struct MTPData {
>      bool         first;
>      /* Used for >4G file sizes */
>      bool         pending;
> -    uint64_t     cached_length;
>      int          fd;
>  };
>  
> @@ -244,6 +243,7 @@ typedef struct {
>  
>  #define MTP_MANUFACTURER  "QEMU"
>  #define MTP_PRODUCT       "QEMU filesharing"
> +#define MTP_WRITE_BUF_SZ  512000

Why not a power of two?  Perhaps use units.h and spell it (512 * KiB) ?

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3226
Virtualization:  qemu.org | libvirt.org

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