From 7724cf27c1e739099c7907ba5b3b8bc86f904595 Mon Sep 17 00:00:00 2001
From: Michael Jeanson <mjeanson@efficios.com>
Date: Fri, 18 Nov 2022 17:49:02 -0500
Subject: [PATCH] Drop support for kernels < 4.4 from LTTng tracer core

Change-Id: I16a57b7d7361d902b18de38faa33943430dedb97
Signed-off-by: Michael Jeanson <mjeanson@efficios.com>
---
 src/Kbuild                              |  7 +++----
 src/lib/ringbuffer/ring_buffer_splice.c | 10 ----------
 src/lttng-events.c                      |  6 ------
 src/lttng-statedump-impl.c              | 23 +----------------------
 4 files changed, 4 insertions(+), 42 deletions(-)

diff --git a/src/Kbuild b/src/Kbuild
index ede6b847..5cc8617d 100644
--- a/src/Kbuild
+++ b/src/Kbuild
@@ -108,10 +108,7 @@ ifneq ($(CONFIG_PREEMPT),)
   lttng-tracer-objs += lttng-context-preemptible.o
 endif
 
-lttng-tracer-objs += $(shell \
-  if [ $(VERSION) -ge 4 \
-    -o \( $(VERSION) -eq 3 -a $(PATCHLEVEL) -ge 15 \) ] ; then \
-    echo "lttng-tracepoint.o" ; fi;)
+lttng-tracer-objs += lttng-tracepoint.o
 
 lttng-tracer-objs += lttng-context-cgroup-ns.o
 
@@ -151,3 +148,5 @@ obj-$(CONFIG_LTTNG) += lib/
 obj-$(CONFIG_LTTNG) += tests/
 
 obj-$(CONFIG_LTTNG_SYSCALLS_EXTRACTOR) += lttng-syscalls-extractor.o
+
+# vim:syntax=make
diff --git a/src/lib/ringbuffer/ring_buffer_splice.c b/src/lib/ringbuffer/ring_buffer_splice.c
index cac44e16..375255b5 100644
--- a/src/lib/ringbuffer/ring_buffer_splice.c
+++ b/src/lib/ringbuffer/ring_buffer_splice.c
@@ -60,19 +60,9 @@ static const struct pipe_buf_operations ring_buffer_pipe_buf_ops = {
 	.steal = generic_pipe_buf_steal,
 	.get = generic_pipe_buf_get
 };
-#elif (LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(3,15,0))
-static const struct pipe_buf_operations ring_buffer_pipe_buf_ops = {
-	.can_merge = 0,
-	.confirm = generic_pipe_buf_confirm,
-	.release = lib_ring_buffer_pipe_buf_release,
-	.steal = generic_pipe_buf_steal,
-	.get = generic_pipe_buf_get
-};
 #else
 static const struct pipe_buf_operations ring_buffer_pipe_buf_ops = {
 	.can_merge = 0,
-	.map = generic_pipe_buf_map,
-	.unmap = generic_pipe_buf_unmap,
 	.confirm = generic_pipe_buf_confirm,
 	.release = lib_ring_buffer_pipe_buf_release,
 	.steal = generic_pipe_buf_steal,
diff --git a/src/lttng-events.c b/src/lttng-events.c
index 827c9d4c..113ccad0 100644
--- a/src/lttng-events.c
+++ b/src/lttng-events.c
@@ -101,15 +101,9 @@ void synchronize_trace(void)
 	synchronize_sched();
 #endif
 
-#if (LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(3,4,0))
 #ifdef CONFIG_PREEMPT_RT_FULL
 	synchronize_rcu();
 #endif
-#else /* (LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(3,4,0)) */
-#ifdef CONFIG_PREEMPT_RT
-	synchronize_rcu();
-#endif
-#endif /* (LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(3,4,0)) */
 }
 
 void lttng_lock_sessions(void)
diff --git a/src/lttng-statedump-impl.c b/src/lttng-statedump-impl.c
index 0593f4c8..22e3628b 100644
--- a/src/lttng-statedump-impl.c
+++ b/src/lttng-statedump-impl.c
@@ -601,21 +601,8 @@ void lttng_statedump_process_ns(struct lttng_kernel_session *session,
 		user_ns = user_ns ? user_ns->parent : NULL;
 	} while (user_ns);
 
-	/*
-	 * Back and forth on locking strategy within Linux upstream for nsproxy.
-	 * See Linux upstream commit 728dba3a39c66b3d8ac889ddbe38b5b1c264aec3
-	 * "namespaces: Use task_lock and not rcu to protect nsproxy"
-	 * for details.
-	 */
-#if (LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(3,17,0) || \
-		LTTNG_UBUNTU_KERNEL_RANGE(3,13,11,36, 3,14,0,0) || \
-		LTTNG_UBUNTU_KERNEL_RANGE(3,16,1,11, 3,17,0,0) || \
-		LTTNG_RHEL_KERNEL_RANGE(3,10,0,229,13,0, 3,11,0,0,0,0))
 	proxy = p->nsproxy;
-#else
-	rcu_read_lock();
-	proxy = task_nsproxy(p);
-#endif
+
 	if (proxy) {
 #if (LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(4,6,0))
 		trace_lttng_statedump_process_cgroup_ns(session, p, proxy->cgroup_ns);
@@ -631,14 +618,6 @@ void lttng_statedump_process_ns(struct lttng_kernel_session *session,
 		trace_lttng_statedump_process_time_ns(session, p, proxy->time_ns);
 #endif
 	}
-#if (LTTNG_LINUX_VERSION_CODE >= LTTNG_KERNEL_VERSION(3,17,0) || \
-		LTTNG_UBUNTU_KERNEL_RANGE(3,13,11,36, 3,14,0,0) || \
-		LTTNG_UBUNTU_KERNEL_RANGE(3,16,1,11, 3,17,0,0) || \
-		LTTNG_RHEL_KERNEL_RANGE(3,10,0,229,13,0, 3,11,0,0,0,0))
-	/* (nothing) */
-#else
-	rcu_read_unlock();
-#endif
 }
 
 static
-- 
2.34.1