Re: [PATCH] mm/swap_slots: use conditional compilation for swap_slots.c

From: Tim Chen
Date: Tue Jan 30 2018 - 18:54:50 EST


On 01/30/2018 03:14 PM, Randy Dunlap wrote:
> From: Randy Dunlap <rdunlap@xxxxxxxxxxxxx>
>
> For mm/swap_slots.c, use the traditional Linux method of conditional
> compilation and linking instead of always compiling it by using
> #ifdef CONFIG_SWAP and #endif for the entire source file (excluding
> header files).
>
> Signed-off-by: Randy Dunlap <rdunlap@xxxxxxxxxxxxx>
> Cc: Tim Chen <tim.c.chen@xxxxxxxxxxxxxxx>
> ---
> mm/Makefile | 4 ++--
> mm/swap_slots.c | 4 ----
> 2 files changed, 2 insertions(+), 6 deletions(-)
>
> Tim, is there some reason that this is done as it currently is?

Rearranging code the way you have proposed makes sense.
You can add my ack.

Thanks.

Tim

>
> --- lnx-415.orig/mm/Makefile
> +++ lnx-415/mm/Makefile
> @@ -37,7 +37,7 @@ obj-y := filemap.o mempool.o oom_kill.
> readahead.o swap.o truncate.o vmscan.o shmem.o \
> util.o mmzone.o vmstat.o backing-dev.o \
> mm_init.o mmu_context.o percpu.o slab_common.o \
> - compaction.o vmacache.o swap_slots.o \
> + compaction.o vmacache.o \
> interval_tree.o list_lru.o workingset.o \
> debug.o $(mmu-y)
>
> @@ -55,7 +55,7 @@ ifdef CONFIG_MMU
> endif
> obj-$(CONFIG_HAVE_MEMBLOCK) += memblock.o
>
> -obj-$(CONFIG_SWAP) += page_io.o swap_state.o swapfile.o
> +obj-$(CONFIG_SWAP) += page_io.o swap_state.o swapfile.o swap_slots.o
> obj-$(CONFIG_FRONTSWAP) += frontswap.o
> obj-$(CONFIG_ZSWAP) += zswap.o
> obj-$(CONFIG_HAS_DMA) += dmapool.o
> --- lnx-415.orig/mm/swap_slots.c
> +++ lnx-415/mm/swap_slots.c
> @@ -34,8 +34,6 @@
> #include <linux/mutex.h>
> #include <linux/mm.h>
>
> -#ifdef CONFIG_SWAP
> -
> static DEFINE_PER_CPU(struct swap_slots_cache, swp_slots);
> static bool swap_slot_cache_active;
> bool swap_slot_cache_enabled;
> @@ -356,5 +354,3 @@ repeat:
>
> return entry;
> }
> -
> -#endif /* CONFIG_SWAP */
>
>