io_uring: add GCOV_PROFILE_URING Kconfig option

If GCOV is enabled and this option is set, it enables code coverage
profiling of the io_uring subsystem. Only use this for test purposes,
as it will impact the runtime performance.
Signed-off-by: Jens Axboe <axboe@kernel.dk>

init/Kconfig

@@ -1687,6 +1687,19 @@ config IO_URING
 	  applications to submit and complete IO through submission and
 	  completion rings that are shared between the kernel and application.
 
+config GCOV_PROFILE_URING
+	bool "Enable GCOV profiling on the io_uring subsystem"
+	depends on GCOV_KERNEL
+	help
+	  Enable GCOV profiling on the io_uring subsystem, to facilitate
+	  code coverage testing.
+
+	  If unsure, say N.
+
+	  Note that this will have a negative impact on the performance of
+	  the io_uring subsystem, hence this should only be enabled for
+	  specific test purposes.
+
 config ADVISE_SYSCALLS
 	bool "Enable madvise/fadvise syscalls" if EXPERT
 	default y

io_uring/Makefile

@@ -2,6 +2,10 @@
 #
 # Makefile for io_uring
 
+ifdef CONFIG_GCOV_PROFILE_URING
+GCOV_PROFILE := y
+endif
+
 obj-$(CONFIG_IO_URING)		+= io_uring.o opdef.o kbuf.o rsrc.o notif.o \
 					tctx.o filetable.o rw.o net.o poll.o \
 					eventfd.o uring_cmd.o openclose.o \