[Qemu-devel] Re: [PATCH] slirp: Use monotonic clock if available (v2)

[Jan Kiszka <jan.kiszka@web.de>]

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Ed Swierk wrote:
> Calling gettimeofday() to compute a time interval can cause problems if
> the system clock jumps forwards or backwards; replace updtime() with
> qemu_get_clock(rt_clock), which calls clock_gettime(CLOCK_MONOTONIC) if
> it is available.
> 
> Also remove some useless macros.
> 
> Signed-off-by: Ed Swierk <eswierk@aristanetworks.com>
> 

Nice fix & cleanup.

Acked-by: Jan Kiszka <jan.kiszka@siemens.com>

> ---
> diff --git a/slirp/slirp.c b/slirp/slirp.c
> index c68c6ab..3798780 100644
> --- a/slirp/slirp.c
> +++ b/slirp/slirp.c
> @@ -22,6 +22,7 @@
>   * THE SOFTWARE.
>   */
>  #include "qemu-common.h"
> +#include "qemu-timer.h"
>  #include "qemu-char.h"
>  #include "slirp.h"
>  #include "hw/hw.h"
> @@ -238,29 +239,6 @@ void slirp_cleanup(Slirp *slirp)
>  #define CONN_CANFRCV(so) (((so)->so_state & (SS_FCANTRCVMORE|SS_ISFCONNECTED)) == SS_ISFCONNECTED)
>  #define UPD_NFDS(x) if (nfds < (x)) nfds = (x)
>  
> -/*
> - * curtime kept to an accuracy of 1ms
> - */
> -#ifdef _WIN32
> -static void updtime(void)
> -{
> -    struct _timeb tb;
> -
> -    _ftime(&tb);
> -
> -    curtime = tb.time * 1000 + tb.millitm;
> -}
> -#else
> -static void updtime(void)
> -{
> -    struct timeval tv;
> -
> -    gettimeofday(&tv, NULL);
> -
> -    curtime = tv.tv_sec * 1000 + tv.tv_usec / 1000;
> -}
> -#endif
> -
>  void slirp_select_fill(int *pnfds,
>                         fd_set *readfds, fd_set *writefds, fd_set *xfds)
>  {
> @@ -399,8 +377,7 @@ void slirp_select_poll(fd_set *readfds, fd_set *writefds, fd_set *xfds,
>      global_writefds = writefds;
>      global_xfds = xfds;
>  
> -	/* Update time */
> -	updtime();
> +    curtime = qemu_get_clock(rt_clock);
>  
>      TAILQ_FOREACH(slirp, &slirp_instances, entry) {
>  	/*
> diff --git a/slirp/slirp.h b/slirp/slirp.h
> index 22058cd..020412c 100644
> --- a/slirp/slirp.h
> +++ b/slirp/slirp.h
> @@ -108,10 +108,6 @@ typedef unsigned char u_int8_t;
>  #include <arpa/inet.h>
>  #endif
>  
> -#ifdef GETTIMEOFDAY_ONE_ARG
> -#define gettimeofday(x, y) gettimeofday(x)
> -#endif
> -
>  /* Systems lacking strdup() definition in <string.h>. */
>  #if defined(ultrix)
>  char *strdup(const char *);
> diff --git a/slirp/slirp_config.h b/slirp/slirp_config.h
> index ebaa99c..e977e77 100644
> --- a/slirp/slirp_config.h
> +++ b/slirp/slirp_config.h
> @@ -187,9 +187,6 @@
>  #define NO_UNIX_SOCKETS
>  #endif
>  
> -/* Define if gettimeofday only takes one argument */
> -#undef GETTIMEOFDAY_ONE_ARG
> -
>  /* Define if you have revoke() */
>  #undef HAVE_REVOKE
>  


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