diff mbox series

[v6,bpf-next,5/9] libbpf: use static const fmt string in __bpf_printk

Message ID 20210917182911.2426606-6-davemarchevsky@fb.com (mailing list archive)
State Accepted
Delegated to: BPF
Headers show
Series bpf: implement variadic printk helper | expand

Checks

Context Check Description
bpf/vmtest-bpf-next success VM_Test
bpf/vmtest-bpf-next-PR success PR summary
netdev/cover_letter success Link
netdev/fixes_present success Link
netdev/patch_count success Link
netdev/tree_selection success Clearly marked for bpf-next
netdev/subject_prefix success Link
netdev/cc_maintainers warning 4 maintainers not CCed: john.fastabend@gmail.com songliubraving@fb.com kpsingh@kernel.org kafai@fb.com
netdev/source_inline success Was 0 now: 0
netdev/verify_signedoff success Link
netdev/module_param success Was 0 now: 0
netdev/build_32bit success Errors and warnings before: 0 this patch: 0
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/verify_fixes success Link
netdev/checkpatch fail ERROR: Macros with complex values should be enclosed in parentheses
netdev/build_allmodconfig_warn success Errors and warnings before: 0 this patch: 0
netdev/header_inline success Link

Commit Message

Dave Marchevsky Sept. 17, 2021, 6:29 p.m. UTC 
The __bpf_printk convenience macro was using a 'char' fmt string holder
as it predates support for globals in libbpf. Move to more efficient
'static const char', but provide a fallback to the old way via
BPF_NO_GLOBAL_DATA so users on old kernels can still use the macro.

Signed-off-by: Dave Marchevsky <davemarchevsky@fb.com>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
---
 tools/lib/bpf/bpf_helpers.h | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)
diff mbox series

Patch

diff --git a/tools/lib/bpf/bpf_helpers.h b/tools/lib/bpf/bpf_helpers.h
index 55a308796625..963b1060d944 100644
--- a/tools/lib/bpf/bpf_helpers.h
+++ b/tools/lib/bpf/bpf_helpers.h
@@ -216,9 +216,15 @@  enum libbpf_tristate {
 		     ___param, sizeof(___param));		\
 })
 
+#ifdef BPF_NO_GLOBAL_DATA
+#define BPF_PRINTK_FMT_MOD
+#else
+#define BPF_PRINTK_FMT_MOD static const
+#endif
+
 #define __bpf_printk(fmt, ...)				\
 ({							\
-	char ____fmt[] = fmt;				\
+	BPF_PRINTK_FMT_MOD char ____fmt[] = fmt;	\
 	bpf_trace_printk(____fmt, sizeof(____fmt),	\
 			 ##__VA_ARGS__);		\
 })