RE: [PATCH] tools/libxc: Drop copy-in in xc_physinfo()

[Wei Chen <Wei.Chen@xxxxxxx>]

Hi Andrew,

> -----Original Message-----
> From: Xen-devel <xen-devel-bounces@xxxxxxxxxxxxxxxxxxxx> On Behalf Of
> Andrew Cooper
> Sent: 2021年12月24日 0:23
> To: Xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxxx>
> Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>; Anthony PERARD
> <anthony.perard@xxxxxxxxxx>; Juergen Gross <jgross@xxxxxxxx>
> Subject: [PATCH] tools/libxc: Drop copy-in in xc_physinfo()
> 
> The first thing XEN_SYSCTL_physinfo does is zero op->u.physinfo.
> 
> Do not copy-in.  It's pointless, and most callers don't initialise their
> xc_physinfo_t buffer to begin with.  Remove the pointless zeroing from the
> remaining callers.
> 
> Spotted by Coverity.
> 
> Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
> ---
> CC: Anthony PERARD <anthony.perard@xxxxxxxxxx>
> CC: Juergen Gross <jgross@xxxxxxxx>
> ---
>  tools/libs/ctrl/xc_misc.c | 2 --
>  tools/libs/light/libxl.c  | 2 +-
>  tools/libs/stat/xenstat.c | 2 +-
>  tools/misc/xenpm.c        | 2 +-
>  tools/xenmon/xenbaked.c   | 2 +-
>  tools/xentrace/xentrace.c | 2 +-
>  6 files changed, 5 insertions(+), 7 deletions(-)
> 
> diff --git a/tools/libs/ctrl/xc_misc.c b/tools/libs/ctrl/xc_misc.c
> index 3820394413a9..265f15ec2da3 100644
> --- a/tools/libs/ctrl/xc_misc.c
> +++ b/tools/libs/ctrl/xc_misc.c
> @@ -195,8 +195,6 @@ int xc_physinfo(xc_interface *xch,
> 
>      sysctl.cmd = XEN_SYSCTL_physinfo;
> 
> -    memcpy(&sysctl.u.physinfo, put_info, sizeof(*put_info));
> -
>      if ( (ret = do_sysctl(xch, &sysctl)) != 0 )
>          return ret;
> 
> diff --git a/tools/libs/light/libxl.c b/tools/libs/light/libxl.c
> index a77aa856fdd6..667ae6409be7 100644
> --- a/tools/libs/light/libxl.c
> +++ b/tools/libs/light/libxl.c
> @@ -351,7 +351,7 @@ const char *libxl_defbool_to_string(libxl_defbool b)
> 
> /*************************************************************************
> *****/
>  int libxl_get_physinfo(libxl_ctx *ctx, libxl_physinfo *physinfo)
>  {
> -    xc_physinfo_t xcphysinfo = { 0 };
> +    xc_physinfo_t xcphysinfo;
>      int rc;
>      long l;
>      GC_INIT(ctx);
> diff --git a/tools/libs/stat/xenstat.c b/tools/libs/stat/xenstat.c
> index e49689aa2da9..8bab2e66a7fe 100644
> --- a/tools/libs/stat/xenstat.c
> +++ b/tools/libs/stat/xenstat.c
> @@ -135,7 +135,7 @@ xenstat_node *xenstat_get_node(xenstat_handle * handle,
> unsigned int flags)
>  {
>  #define DOMAIN_CHUNK_SIZE 256
>       xenstat_node *node;
> -     xc_physinfo_t physinfo = { 0 };
> +     xc_physinfo_t physinfo;
>       xc_domaininfo_t domaininfo[DOMAIN_CHUNK_SIZE];
>       int new_domains;
>       unsigned int i;
> diff --git a/tools/misc/xenpm.c b/tools/misc/xenpm.c
> index d0191d498484..4f8cde690a7c 100644
> --- a/tools/misc/xenpm.c
> +++ b/tools/misc/xenpm.c
> @@ -1244,7 +1244,7 @@ struct {
>  int main(int argc, char *argv[])
>  {
>      int i, ret = 0;
> -    xc_physinfo_t physinfo = { 0 };
> +    xc_physinfo_t physinfo;
>      int nr_matches = 0;
>      int matches_main_options[ARRAY_SIZE(main_options)];
> 
> diff --git a/tools/xenmon/xenbaked.c b/tools/xenmon/xenbaked.c
> index 1ed34334c824..7591de7c609f 100644
> --- a/tools/xenmon/xenbaked.c
> +++ b/tools/xenmon/xenbaked.c
> @@ -436,7 +436,7 @@ static struct t_struct *map_tbufs(unsigned long
> tbufs_mfn, unsigned int num,
>   */
>  static unsigned int get_num_cpus(void)
>  {
> -    xc_physinfo_t physinfo = { 0 };
> +    xc_physinfo_t physinfo;
>      xc_interface *xc_handle = xc_interface_open(0,0,0);
>      int ret;
> 
> diff --git a/tools/xentrace/xentrace.c b/tools/xentrace/xentrace.c
> index a8903ebf4625..864e30d50cc3 100644
> --- a/tools/xentrace/xentrace.c
> +++ b/tools/xentrace/xentrace.c
> @@ -589,7 +589,7 @@ static void set_evt_mask(uint32_t mask)
>   */
>  static unsigned int get_num_cpus(void)
>  {
> -    xc_physinfo_t physinfo = { 0 };
> +    xc_physinfo_t physinfo;
>      int ret;
> 
>      ret = xc_physinfo(xc_handle, &physinfo);
> --
> 2.11.0
> 

Reviewed-by: Wei Chen <Wei.Chen@xxxxxxx>