From 896fd52618e9c209e7a5254e8efdba4e7865e61d Mon Sep 17 00:00:00 2001 From: Greg Kroah-Hartman Date: Tue, 13 Jun 2023 19:37:41 +0000 Subject: [PATCH] Revert "binder: add lockless binder_alloc_(set|get)_vma()" This reverts commit d7cee853bcb07e02c6c5a65037eac2ab081c4337. It breaks the Android KABI and will be brought back at a later time when it is safe to do so. Bug: 161946584 Change-Id: I192028d99847d9a4421ed953a765fb8dadbbfce7 Signed-off-by: Greg Kroah-Hartman --- drivers/android/binder_alloc.c | 24 ++++++++++-------------- 1 file changed, 10 insertions(+), 14 deletions(-) diff --git a/drivers/android/binder_alloc.c b/drivers/android/binder_alloc.c index 8dc677f58ebb..f47d9a20707b 100644 --- a/drivers/android/binder_alloc.c +++ b/drivers/android/binder_alloc.c @@ -310,18 +310,17 @@ err_no_vma: return vma ? -ENOMEM : -ESRCH; } -static inline void binder_alloc_set_vma(struct binder_alloc *alloc, - struct vm_area_struct *vma) -{ - /* pairs with smp_load_acquire in binder_alloc_get_vma() */ - smp_store_release(&alloc->vma, vma); -} - static inline struct vm_area_struct *binder_alloc_get_vma( struct binder_alloc *alloc) { - /* pairs with smp_store_release in binder_alloc_set_vma() */ - return smp_load_acquire(&alloc->vma); + struct vm_area_struct *vma = NULL; + + if (alloc->vma) { + /* Look at description in binder_alloc_set_vma */ + smp_rmb(); + vma = alloc->vma; + } + return vma; } static bool debug_low_async_space_locked(struct binder_alloc *alloc, int pid) @@ -384,7 +383,6 @@ static struct binder_buffer *binder_alloc_new_buf_locked( size_t size, data_offsets_size; int ret; - /* Check binder_alloc is fully initialized */ if (!binder_alloc_get_vma(alloc)) { binder_alloc_debug(BINDER_DEBUG_USER_ERROR, "%d: binder_alloc_buf, no vma\n", @@ -781,9 +779,7 @@ int binder_alloc_mmap_handler(struct binder_alloc *alloc, buffer->free = 1; binder_insert_free_buffer(alloc, buffer); alloc->free_async_space = alloc->buffer_size / 2; - - /* Signal binder_alloc is fully initialized */ - binder_alloc_set_vma(alloc, vma); + alloc->vma = vma; return 0; @@ -965,7 +961,7 @@ int binder_alloc_get_allocated_count(struct binder_alloc *alloc) */ void binder_alloc_vma_close(struct binder_alloc *alloc) { - binder_alloc_set_vma(alloc, NULL); + alloc->vma = 0; } /**