ANDROID: mm: Add vendor hook in swapon()

This patch add a vendor hook in swapon() for changing swap
info flags to meet the capability of certain swap devices.

Bug: 368512254
Change-Id: I009f039179db3d4ac23039c7ddd09fa852f3729f
Signed-off-by: Chinwen Chang <chinwen.chang@mediatek.com>

drivers/android/vendor_hooks.c

@@ -449,6 +449,7 @@ EXPORT_TRACEPOINT_SYMBOL_GPL(android_rvh_vmscan_kswapd_wake);
 EXPORT_TRACEPOINT_SYMBOL_GPL(android_rvh_vmscan_kswapd_done);
 EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_customize_alloc_gfp);
 EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_mm_kcompactd_cpu_online);
+EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_adjust_swap_info_flags);
 EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_direct_reclaim_begin);
 EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_direct_reclaim_end);
 EXPORT_TRACEPOINT_SYMBOL_GPL(android_rvh_do_read_fault);

include/trace/hooks/mm.h

@@ -399,6 +399,9 @@ DECLARE_HOOK(android_vh_customize_alloc_gfp,
 DECLARE_HOOK(android_vh_mm_kcompactd_cpu_online,
 	TP_PROTO(int cpu),
 	TP_ARGS(cpu));
+DECLARE_HOOK(android_vh_adjust_swap_info_flags,
+	TP_PROTO(unsigned long *flags),
+	TP_ARGS(flags));
 DECLARE_HOOK(android_rvh_alloc_pages_reclaim_start,
 	TP_PROTO(gfp_t gfp_mask, int order, int *alloc_flags),
 	TP_ARGS(gfp_mask, order, alloc_flags));

mm/swapfile.c

@@ -50,6 +50,7 @@
 #include "internal.h"
 #include "swap.h"
 #include <trace/hooks/bl_hib.h>
+#include <trace/hooks/mm.h>
 
 static bool swap_count_continued(struct swap_info_struct *, pgoff_t,
 				 unsigned char);
@@ -3500,6 +3501,8 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags)
 	if (si->bdev && bdev_synchronous(si->bdev))
 		si->flags |= SWP_SYNCHRONOUS_IO;
 
+	trace_android_vh_adjust_swap_info_flags(&si->flags);
+
 	if (si->bdev && !hibernation_swap && bdev_nonrot(si->bdev)) {
 		si->flags |= SWP_SOLIDSTATE;