tracing: Use address-of operator on section symbols

[ Upstream commit bf2cbe044da275021b2de5917240411a19e5c50d ]

Clang warns:

../kernel/trace/trace.c:9335:33: warning: array comparison always
evaluates to true [-Wtautological-compare]
        if (__stop___trace_bprintk_fmt != __start___trace_bprintk_fmt)
                                       ^
1 warning generated.

These are not true arrays, they are linker defined symbols, which are
just addresses. Using the address of operator silences the warning and
does not change the runtime result of the check (tested with some print
statements compiled in with clang + ld.lld and gcc + ld.bfd in QEMU).

Link: http://lkml.kernel.org/r/20200220051011.26113-1-natechancellor@gmail.com
Link: https://github.com/ClangBuiltLinux/linux/issues/893
Suggested-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 67cee2774a6b8b374467b4b4ebecf2c451e7bb86..2388fb50d1885341f44ea1556d0ad38b9eac4da5 100644 (file)
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -7696,7 +7696,7 @@ __init static int tracer_alloc_buffers(void)
                goto out_free_buffer_mask;
 
        /* Only allocate trace_printk buffers if a trace_printk exists */
-       if (__stop___trace_bprintk_fmt != __start___trace_bprintk_fmt)
+       if (&__stop___trace_bprintk_fmt != &__start___trace_bprintk_fmt)
                /* Must be called before global_trace.buffer is allocated */
                trace_printk_init_buffers();