[OE-core] [PATCH] perf: workaround the error cased by maybe-uninitialized warning

[Dengke Du]

When enable DEBUG_BUILD, the perf build failed by the following error:
    libbpf.c:727:36: error: 'data' may be used uninitialized in this function [-Werror=maybe-uninitialized]
This is ok until Khem commit a patch in oe-core:
    16643b03227466e2c80a24c2d079fe36e89553c1
This commit import "-Og" option to "DEBUG_OPTIMIZATION", result in this error.

Actually, the warning was misinformation. We explore the code in libbpf.c:
    https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/tools/lib/bpf/libbpf.c#n640
--------------------------------------------------------------------------
	if (scn)
		data = elf_getdata(scn, NULL);
	if (!scn || !data) {
		pr_warning("failed to get Elf_Data from map section %d\n",
			   obj->efile.maps_shndx);
		return -EINVAL;
	}
	......
	using data...
	......
--------------------------------------------------------------------------
If the 'scn' was not null, the data will be initialized. if the data was null,
the function will return -EINVAL, so the data must be not null, but compiler
can't see it in 'if' code block, so treat it as 'maybe-uninitialized'.

Signed-off-by: Dengke Du <dengke.du at windriver.com>
---
 meta/recipes-kernel/perf/perf.bb | 1 +
 1 file changed, 1 insertion(+)

diff --git a/meta/recipes-kernel/perf/perf.bb b/meta/recipes-kernel/perf/perf.bb
index 5acdcfb..546076f 100644
--- a/meta/recipes-kernel/perf/perf.bb
+++ b/meta/recipes-kernel/perf/perf.bb
@@ -271,3 +271,4 @@ FILES_${PN}-perl = "${libexecdir}/perf-core/scripts/perl"
 
 
 INHIBIT_PACKAGE_DEBUG_SPLIT="1"
+DEBUG_OPTIMIZATION_append = " -Wno-error=maybe-uninitialized"
-- 
2.7.4