[openwrt/openwrt] kernel: add missing symbol

[LEDE Commits]

stintel pushed a commit to openwrt/openwrt.git, branch master:
https://git.openwrt.org/38106a484cdff85cd9b52bb2978c8b40f8b2c942

commit 38106a484cdff85cd9b52bb2978c8b40f8b2c942
Author: Stijn Tintel <stijn at linux-ipv6.be>
AuthorDate: Sat Nov 6 20:55:57 2021 +0200

    kernel: add missing symbol
    
    Enabling KERNEL_FTRACE exposes the HIST_TRIGGERS triggers symbol. Add a
    build option for it to fix build failures with KERNEL_FTRACE enabled.
    
    Signed-off-by: Stijn Tintel <stijn at linux-ipv6.be>
---
 config/Config-kernel.in | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/config/Config-kernel.in b/config/Config-kernel.in
index e993dc0d8c..8ebe1b7070 100644
--- a/config/Config-kernel.in
+++ b/config/Config-kernel.in
@@ -349,6 +349,19 @@ config KERNEL_PREEMPT_TRACER
 	  enabled. This option and the irqs-off timing option can be
 	  used together or separately.)
 
+config KERNEL_HIST_TRIGGERS
+	bool "Histogram triggers"
+	depends on KERNEL_FTRACE
+	help
+	  Hist triggers allow one or more arbitrary trace event fields to be
+	  aggregated into hash tables and dumped to stdout by reading a
+	  debugfs/tracefs file. They're useful for gathering quick and dirty
+	  (though precise) summaries of event activity as an initial guide for
+	  further investigation using more advanced tools.
+
+	  Inter-event tracing of quantities such as latencies is also
+	  supported using hist triggers under this option.
+
 config KERNEL_DEBUG_KERNEL
 	bool
 	default n