ctags indexing ("make tags" command) throws this warning:
    ctags: Warning: include/linux/notifier.h:125:
    null expansion of name pattern "\1"
This is the result of DEFINE_PER_CPU() macro expansion.  Fix that by
getting rid of line break.
Similar fix was already done in commit 
25528213fe9f ("tags: Fix
DEFINE_PER_CPU expansions"), but this one probably wasn't noticed.
Link: http://lkml.kernel.org/r/20181030202808.28027-1-semen.protsenko@linaro.org
Fixes: 9c80172b902d ("kernel/SRCU: provide a static initializer")
Signed-off-by: Sam Protsenko <semen.protsenko@linaro.org>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 
 
 #ifdef CONFIG_TREE_SRCU
 #define _SRCU_NOTIFIER_HEAD(name, mod)                         \
-       static DEFINE_PER_CPU(struct srcu_data,                 \
-                       name##_head_srcu_data);                 \
+       static DEFINE_PER_CPU(struct srcu_data, name##_head_srcu_data); \
        mod struct srcu_notifier_head name =                    \
                        SRCU_NOTIFIER_INIT(name, name##_head_srcu_data)