[DTrace-devel] [PATCH v4 02/19] Add a dt_provider_discover() function
Kris Van Hees
kris.van.hees at oracle.com
Mon Oct 28 16:19:09 UTC 2024
On Mon, Oct 28, 2024 at 01:18:35AM -0400, eugene.loh at oracle.com wrote:
> From: Eugene Loh <eugene.loh at oracle.com>
>
> It is possible for new providers and probes to appear after dtrace_go().
> Add a function that can be called for such discovery, on a per-provider
> basis. Each provider that supports such discovery needs to provide:
>
> *) a function discover() that performs discovery on behalf of the provider
>
> *) a function add_probe() that adds a particular (discovered) probe
>
> To support looping over providers, move dt_providers[] from
> dt_open.c to dt_provider.c and extern it in dt_provider.h.
>
> Signed-off-by: Eugene Loh <eugene.loh at oracle.com>
> ---
> libdtrace/dt_bpf.c | 4 +++
> libdtrace/dt_open.c | 22 +---------------
> libdtrace/dt_provider.c | 57 +++++++++++++++++++++++++++++++++++++++++
> libdtrace/dt_provider.h | 6 +++++
> libdtrace/dt_work.c | 3 +++
> 5 files changed, 71 insertions(+), 21 deletions(-)
>
> diff --git a/libdtrace/dt_bpf.c b/libdtrace/dt_bpf.c
> index ad11d178e..856110306 100644
> --- a/libdtrace/dt_bpf.c
> +++ b/libdtrace/dt_bpf.c
> @@ -1275,6 +1275,10 @@ dt_bpf_load_progs(dtrace_hdl_t *dtp, uint_t cflags)
> int fd;
> int rc = -1;
>
> + /* Handle probes discovered after compilation. */
> + if (prp->prov->impl->add_probe)
> + prp->prov->impl->add_probe(dtp, prp);
> +
> dp = prp->difo;
> if (dp == NULL)
> continue;
> diff --git a/libdtrace/dt_open.c b/libdtrace/dt_open.c
> index 848141ddc..1f586fc4f 100644
> --- a/libdtrace/dt_open.c
> +++ b/libdtrace/dt_open.c
> @@ -61,26 +61,6 @@ const dt_version_t _dtrace_versions[] = {
> 0
> };
>
> -/*
> - * List of provider modules that register providers and probes. A single
> - * provider module may create multiple providers.
> - */
> -static const dt_provimpl_t *dt_providers[] = {
> - &dt_dtrace, /* list dt_dtrace first */
> - &dt_cpc,
> - &dt_fbt_fprobe,
> - &dt_io,
> - &dt_ip,
> - &dt_lockstat,
> - &dt_proc,
> - &dt_profile,
> - &dt_rawtp,
> - &dt_sched,
> - &dt_sdt,
> - &dt_syscall,
> - &dt_uprobe,
> -};
> -
> /*
> * Table of global identifiers. This is used to populate the global identifier
> * hash when a new dtrace client open occurs. For more info see dt_ident.h.
> @@ -1210,7 +1190,7 @@ dtrace_init(dtrace_hdl_t *dtp)
> * known providers.
> */
> dt_probe_init(dtp);
> - for (i = 0; i < ARRAY_SIZE(dt_providers); i++) {
> + for (i = 0; dt_providers[i]; i++) {
> int n;
>
> n = dt_providers[i]->populate(dtp);
> diff --git a/libdtrace/dt_provider.c b/libdtrace/dt_provider.c
> index 8cfef0ba2..5f9766183 100644
> --- a/libdtrace/dt_provider.c
> +++ b/libdtrace/dt_provider.c
> @@ -18,10 +18,32 @@
> #include <port.h>
>
> #include <dt_provider.h>
> +#include <dt_probe.h>
> #include <dt_module.h>
> #include <dt_string.h>
> #include <dt_list.h>
>
> +/*
> + * List of provider modules that register providers and probes. A single
> + * provider module may create multiple providers.
> + */
> +const dt_provimpl_t *dt_providers[] = {
> + &dt_dtrace, /* list dt_dtrace first */
> + &dt_cpc,
> + &dt_fbt_fprobe,
> + &dt_io,
> + &dt_ip,
> + &dt_lockstat,
> + &dt_proc,
> + &dt_profile,
> + &dt_rawtp,
> + &dt_sched,
> + &dt_sdt,
> + &dt_syscall,
> + &dt_uprobe,
> + NULL
> +};
> +
> static uint32_t
> dt_provider_hval(const dt_provider_t *pvp)
> {
> @@ -149,3 +171,38 @@ dt_provider_xref(dtrace_hdl_t *dtp, dt_provider_t *pvp, id_t id)
> BT_SET(pvp->pv_xrefs, id);
> return 0;
> }
> +
> +int
> +dt_provider_discover(dtrace_hdl_t *dtp)
> +{
> + int i, prid = dtp->dt_probe_id;
> +
> + /* Discover new probes. */
> + for (i = 0; dt_providers[i]; i++) {
> + int n;
> +
> + if (dt_providers[i]->discover == NULL)
> + continue;
> +
> + n = dt_providers[i]->discover(dtp);
> + if (n < 0)
> + return -1; /* errno is already set */
> + }
My apologies for not seeing this sooner, but can't this simply be:
for (i = 0; dt_providers[i]; i++) {
if (dt_providers[i]->discover && dt_providers[i]->discover(dtp) < 0)
return -1; /* errno is already set */
}
> +
> + /* Add them. */
> + for ( ; prid < dtp->dt_probe_id; prid++) {
> + dt_probe_t *prp = dtp->dt_probes[prid];
> + int rc;
> +
> + dt_probe_enable(dtp, prp);
> +
> + if (prp->prov->impl->add_probe == NULL)
> + continue;
> +
> + rc = prp->prov->impl->add_probe(dtp, prp);
> + if (rc < 0)
> + return rc;
> + }
> +
> + return 0;
> +}
> diff --git a/libdtrace/dt_provider.h b/libdtrace/dt_provider.h
> index 17b1844cb..384d4fd33 100644
> --- a/libdtrace/dt_provider.h
> +++ b/libdtrace/dt_provider.h
> @@ -62,6 +62,9 @@ typedef struct dt_provimpl {
> int (*probe_info)(dtrace_hdl_t *dtp, /* get probe info */
> const struct dt_probe *prp,
> int *argcp, dt_argdesc_t **argvp);
> + int (*discover)(dtrace_hdl_t *dtp); /* discover new probes */
> + int (*add_probe)(dtrace_hdl_t *dtp, /* add a new probe */
> + struct dt_probe *prp);
> void (*detach)(dtrace_hdl_t *dtp, /* probe cleanup */
> const struct dt_probe *prb);
> void (*probe_destroy)(dtrace_hdl_t *dtp, /* free probe data */
> @@ -86,6 +89,8 @@ extern dt_provimpl_t dt_sdt;
> extern dt_provimpl_t dt_syscall;
> extern dt_provimpl_t dt_uprobe;
>
> +extern const dt_provimpl_t *dt_providers[];
> +
> typedef struct dt_provider {
> dt_list_t pv_list; /* list forward/back pointers */
> struct dt_hentry he; /* htab links */
> @@ -110,6 +115,7 @@ extern dt_provider_t *dt_provider_create(dtrace_hdl_t *, const char *,
> const dt_provimpl_t *,
> const dtrace_pattr_t *, void *);
> extern int dt_provider_xref(dtrace_hdl_t *, dt_provider_t *, id_t);
> +extern int dt_provider_discover(dtrace_hdl_t *dtp);
>
> #ifdef __cplusplus
> }
> diff --git a/libdtrace/dt_work.c b/libdtrace/dt_work.c
> index 11335345a..5318cdb7e 100644
> --- a/libdtrace/dt_work.c
> +++ b/libdtrace/dt_work.c
> @@ -362,6 +362,9 @@ dtrace_work(dtrace_hdl_t *dtp, FILE *fp, dtrace_consume_probe_f *pfunc,
> dtrace_workstatus_t rval;
> int gen;
>
> + if (dt_provider_discover(dtp) < 0)
> + return DTRACE_WORKSTATUS_ERROR;
> +
> switch (dtrace_status(dtp)) {
> case DTRACE_STATUS_EXITED:
> case DTRACE_STATUS_STOPPED:
> --
> 2.43.5
>
More information about the DTrace-devel
mailing list