[DTrace-devel] [PATCH 05/19] Add flag to dt_pid_create_probes()

[Kris Van Hees]

On Thu, Aug 29, 2024 at 01:25:44AM -0400, eugene.loh at oracle.com wrote:
> From: Eugene Loh <eugene.loh at oracle.com>
> 
> The function dt_pid_create_probes() creates both pid and usdt probes.
> Once the dtrace session has started, however, we only need to watch
> for new usdt probes.  So add a usdt_only argument to the function.

It would be better I think to create two functions, one for trying to match pid
probes, and one for trying to match USDT probes, and to call those two functions
from dt_pid_create_probes().  And then, after tracing has started, only the one
dealing with USDT probes needs to be called.

> Signed-off-by: Eugene Loh <eugene.loh at oracle.com>
> ---
>  libdtrace/dt_cc.c  | 2 +-
>  libdtrace/dt_pid.c | 4 ++--
>  libdtrace/dt_pid.h | 3 +--
>  3 files changed, 4 insertions(+), 5 deletions(-)
> 
> diff --git a/libdtrace/dt_cc.c b/libdtrace/dt_cc.c
> index e66d76fb..cfd4d3d1 100644
> --- a/libdtrace/dt_cc.c
> +++ b/libdtrace/dt_cc.c
> @@ -282,7 +282,7 @@ dt_setcontext(dtrace_hdl_t *dtp, const dtrace_probedesc_t *pdp)
>  	    isdigit(pdp->prv[strlen(pdp->prv) - 1]) &&
>  	    ((pvp = dt_provider_lookup(dtp, pdp->prv)) == NULL ||
>  	     pvp->pv_flags & DT_PROVIDER_PID) &&
> -	    dt_pid_create_probes((dtrace_probedesc_t *)pdp, dtp, yypcb) != 0) {
> +	    dt_pid_create_probes((dtrace_probedesc_t *)pdp, dtp, yypcb, 0) != 0) {
>  		longjmp(yypcb->pcb_jmpbuf, EDT_COMPILER);
>  	}
>  
> diff --git a/libdtrace/dt_pid.c b/libdtrace/dt_pid.c
> index 996543b1..3f3453af 100644
> --- a/libdtrace/dt_pid.c
> +++ b/libdtrace/dt_pid.c
> @@ -1095,7 +1095,7 @@ dt_pid_get_pid(const dtrace_probedesc_t *pdp, dtrace_hdl_t *dtp, dt_pcb_t *pcb,
>  }
>  
>  int
> -dt_pid_create_probes(dtrace_probedesc_t *pdp, dtrace_hdl_t *dtp, dt_pcb_t *pcb)
> +dt_pid_create_probes(dtrace_probedesc_t *pdp, dtrace_hdl_t *dtp, dt_pcb_t *pcb, int usdt_only)
>  {
>  	char provname[DTRACE_PROVNAMELEN];
>  	dt_proc_t *dpr;
> @@ -1109,7 +1109,7 @@ dt_pid_create_probes(dtrace_probedesc_t *pdp, dtrace_hdl_t *dtp, dt_pcb_t *pcb)
>  
>  	snprintf(provname, sizeof(provname), "pid%d", (int)pid);
>  
> -	if (gmatch(provname, pdp->prv) != 0) {
> +	if ((usdt_only == 0) && gmatch(provname, pdp->prv) != 0) {
>  		if (dt_proc_grab_lock(dtp, pid, DTRACE_PROC_WAITING) < 0) {
>  			dt_pid_error(dtp, pcb, NULL, D_PROC_GRAB,
>  			    "failed to grab process %d", (int)pid);
> diff --git a/libdtrace/dt_pid.h b/libdtrace/dt_pid.h
> index 497c7751..dc200f4d 100644
> --- a/libdtrace/dt_pid.h
> +++ b/libdtrace/dt_pid.h
> @@ -16,8 +16,7 @@
>  extern "C" {
>  #endif
>  
> -extern int dt_pid_create_probes(dtrace_probedesc_t *, dtrace_hdl_t *,
> -				dt_pcb_t *);
> +extern int dt_pid_create_probes(dtrace_probedesc_t *, dtrace_hdl_t *, dt_pcb_t *, int);
>  extern int dt_pid_create_probes_module(dtrace_hdl_t *, dt_proc_t *);
>  extern pid_t dt_pid_get_pid(const dtrace_probedesc_t *, dtrace_hdl_t *, dt_pcb_t *,
>  			    dt_proc_t *);
> -- 
> 2.43.5
>