[DTrace-devel] [PATCH] sdt: support min and max kernel versions for probe dependencies

[Kris Van Hees]

THe underlying probes that are used to trigger SDT probes may be kernel
version dependent.  Adding optional minimum and maximum specifications
(using DT_VERSION_NUMBER(x, y, z)) allows us to specify what kernels a
certain dependency can be expected to work on.

Signed-off-by: Kris Van Hees <kris.van.hees at oracle.com>
---
 libdtrace/dt_provider_sdt.c | 10 ++++++++++
 libdtrace/dt_provider_sdt.h |  8 +++++---
 2 files changed, 15 insertions(+), 3 deletions(-)

diff --git a/libdtrace/dt_provider_sdt.c b/libdtrace/dt_provider_sdt.c
index ebd8b107..823e9b2a 100644
--- a/libdtrace/dt_provider_sdt.c
+++ b/libdtrace/dt_provider_sdt.c
@@ -87,6 +87,16 @@ dt_sdt_enable(dtrace_hdl_t *dtp, dt_probe_t *prp)
 		if (strcmp(prp->desc->prb, dep->name) != 0)
 			continue;
 
+		/*
+		 * If the dependency specifies a minimum and/or maximum kernel
+		 * version, skip this dependency if the runtime kernel version
+		 * does not fall in the specified range.
+		 */
+		if (dep->kver_min && dtp->dt_kernver < dep->kver_min)
+			continue;
+		if (dep->kver_max && dtp->dt_kernver > dep->kver_max)
+			continue;
+
 		if (dtrace_str2desc(dtp, dep->spec, dep->str, &pd) == -1)
 			return;
 
diff --git a/libdtrace/dt_provider_sdt.h b/libdtrace/dt_provider_sdt.h
index 86f3b84b..8595e2c8 100644
--- a/libdtrace/dt_provider_sdt.h
+++ b/libdtrace/dt_provider_sdt.h
@@ -19,14 +19,16 @@ extern "C" {
  * Probe dependencies
  *
  * SDT probes are implemented using probes made available by other providers.
- * THe probe dependency table associates each SDT probe with one or more probe
- * specifications (possibly containing wildcards).  Each matching probe will
- * have SDT lockstat probe added as a dependent probe.
+ * The probe dependency table associates each SDT probe with one or more probe
+ * specifications (possibly containing wildcards).  On optional minimum kernel
+ * version can also be specified (assigned using DT_VERSION_NUMBER(x, y, z)).
  */
 typedef struct probe_dep {
 	const char		*name;			/* probe name */
 	dtrace_probespec_t	spec;			/* spec type */
 	const char		*str;			/* spec string */
+	dt_version_t		kver_min;		/* minimum kernver */
+	dt_version_t		kver_max;		/* maximum kernver */
 } probe_dep_t;
 
 /*
-- 
2.39.3