dev_printk: Add and use dev_no_printk()

dev_printk: Add and use dev_no_printk()

[ Upstream commit c26ec799042a3888935d59b599f33e41efedf5f8 ]

When printk-indexing is enabled, each dev_printk() invocation emits a
pi_entry structure.  This is even true when the dev_printk() is
protected by an always-false check, as is typically the case for debug
messages: while the actual code to print the message is optimized out by
the compiler, the pi_entry structure is still emitted.

Avoid emitting pi_entry structures for unavailable dev_printk() kernel
messages by:
  1. Introducing a dev_no_printk() helper, mimicked after the existing
     no_printk() helper, which calls _dev_printk() instead of
     dev_printk(),
  2. Replacing all "if (0) dev_printk(...)" constructs by calls to the
     new helper.

This reduces the size of an arm64 defconfig kernel with
CONFIG_PRINTK_INDEX=y by 957 KiB.

Fixes: ad7d61f159db7397 ("printk: index: Add indexing support to dev_printk")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Xiubo Li <xiubli@redhat.com>
Reviewed-by: Chris Down <chris@chrisdown.name>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/8583d54f1687c801c6cda8edddf2cf0344c6e883.1709127473.git.geert+renesas@glider.be
Signed-off-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>