[PATCH 20/38] Add a hook for a provider-specific "update" function

eugene.loh
2024-06-27T05:39:11Z

From: Eugene Loh <eugene.loh@oracle.com>

For up-coming USDT-probe support, we need to update a BPF map
-- at least when the dtrace session starts but possibly also later
to support systemwide USDT tracing for processes that may start up
later.

One way to do this is with a USDT-specific update function.

For now, let's add a hook for providers to have provider-specific
update functions. User space can either call

for (i = 0; i < ARRAY_SIZE(dt_providers); i++) {
if (dt_providers[i]->update)
dt_providers[i]->update(...);
}

any time it likes. Or it can call dt_usdt.update(...).

This is for WIP. A different approach can be adopted later instead.

Signed-off-by: Eugene Loh <eugene.loh@oracle.com>
---
libdtrace/dt_provider.h | 2 ++
1 file changed, 2 insertions(+)

diff --git a/libdtrace/dt_provider.h b/libdtrace/dt_provider.h
index b1b1b1b8..71b5a3c4 100644
--- a/libdtrace/dt_provider.h
+++ b/libdtrace/dt_provider.h
@@ -71,6 +71,8 @@ typedef struct dt_provimpl {
void *datap);
void (*destroy)(dtrace_hdl_t *dtp, /* free provider data */
void *datap);
+ void (*update)(dtrace_hdl_t *dtp, /* update provider-specific info */
+ void *datap);
} dt_provimpl_t;

/* list dt_dtrace first */
--
2.18.4