[PATCH v6 1/9] Revert "binder: switch alloc->mutex to spinlock_t"

Carlos Llamas
2024-12-03T21:55:16Z

This reverts commit 7710e2cca32e7f3958480e8bd44f50e29d0c2509.

In preparation for concurrent page installations, restore the original
alloc->mutex which will serialize zap_page_range_single() against page
installations in subsequent patches (instead of the mmap_sem).

Resolved trivial conflicts with commit 2c10a20f5e84a ("binder_alloc: Fix
sleeping function called from invalid context") and commit da0c02516c50
("mm/list_lru: simplify the list_lru walk callback function").

Cc: Mukesh Ojha <quic_mojha@quicinc.com>
Reviewed-by: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: Carlos Llamas <cmllamas@google.com>
---
drivers/android/binder_alloc.c | 46 +++++++++++++++++-----------------
drivers/android/binder_alloc.h | 10 ++++----
2 files changed, 28 insertions(+), 28 deletions(-)

diff --git a/drivers/android/binder_alloc.c b/drivers/android/binder_alloc.c
index a738e7745865..52f6aa3232e1 100644
--- a/drivers/android/binder_alloc.c
+++ b/drivers/android/binder_alloc.c
@@ -169,9 +169,9 @@ struct binder_buffer *binder_alloc_prepare_to_free(struct binder_alloc *alloc,
{
struct binder_buffer *buffer;

- spin_lock(&alloc->lock);
+ mutex_lock(&alloc->mutex);
buffer = binder_alloc_prepare_to_free_locked(alloc, user_ptr);
- spin_unlock(&alloc->lock);
+ mutex_unlock(&alloc->mutex);
return buffer;
}

@@ -597,10 +597,10 @@ struct binder_buffer *binder_alloc_new_buf(struct binder_alloc *alloc,
if (!next)
return ERR_PTR(-ENOMEM);

- spin_lock(&alloc->lock);
+ mutex_lock(&alloc->mutex);
buffer = binder_alloc_new_buf_locked(alloc, next, size, is_async);
if (IS_ERR(buffer)) {
- spin_unlock(&alloc->lock);
+ mutex_unlock(&alloc->mutex);
goto out;
}

@@ -608,7 +608,7 @@ struct binder_buffer *binder_alloc_new_buf(struct binder_alloc *alloc,
buffer->offsets_size = offsets_size;
buffer->extra_buffers_size = extra_buffers_size;
buffer->pid = current->tgid;
- spin_unlock(&alloc->lock);
+ mutex_unlock(&alloc->mutex);

ret = binder_install_buffer_pages(alloc, buffer, size);
if (ret) {
@@ -785,17 +785,17 @@ void binder_alloc_free_buf(struct binder_alloc *alloc,
* We could eliminate the call to binder_alloc_clear_buf()
* from binder_alloc_deferred_release() by moving this to
* binder_free_buf_locked(). However, that could
- * increase contention for the alloc->lock if clear_on_free
- * is used frequently for large buffers. This lock is not
+ * increase contention for the alloc mutex if clear_on_free
+ * is used frequently for large buffers. The mutex is not
* needed for correctness here.
*/
if (buffer->clear_on_free) {
binder_alloc_clear_buf(alloc, buffer);
buffer->clear_on_free = false;
}
- spin_lock(&alloc->lock);
+ mutex_lock(&alloc->mutex);
binder_free_buf_locked(alloc, buffer);
- spin_unlock(&alloc->lock);
+ mutex_unlock(&alloc->mutex);
}

/**
@@ -893,7 +893,7 @@ void binder_alloc_deferred_release(struct binder_alloc *alloc)
struct binder_buffer *buffer;

buffers = 0;
- spin_lock(&alloc->lock);
+ mutex_lock(&alloc->mutex);
BUG_ON(alloc->vma);

while ((n = rb_first(&alloc->allocated_buffers))) {
@@ -940,7 +940,7 @@ void binder_alloc_deferred_release(struct binder_alloc *alloc)
page_count++;
}
}
- spin_unlock(&alloc->lock);
+ mutex_unlock(&alloc->mutex);
kvfree(alloc->pages);
if (alloc->mm)
mmdrop(alloc->mm);
@@ -964,7 +964,7 @@ void binder_alloc_print_allocated(struct seq_file *m,
struct binder_buffer *buffer;
struct rb_node *n;

- spin_lock(&alloc->lock);
+ mutex_lock(&alloc->mutex);
for (n = rb_first(&alloc->allocated_buffers); n; n = rb_next(n)) {
buffer = rb_entry(n, struct binder_buffer, rb_node);
seq_printf(m, " buffer %d: %lx size %zd:%zd:%zd %s\n",
@@ -974,7 +974,7 @@ void binder_alloc_print_allocated(struct seq_file *m,
buffer->extra_buffers_size,
buffer->transaction ? "active" : "delivered");
}
- spin_unlock(&alloc->lock);
+ mutex_unlock(&alloc->mutex);
}

/**
@@ -991,7 +991,7 @@ void binder_alloc_print_pages(struct seq_file *m,
int lru = 0;
int free = 0;

- spin_lock(&alloc->lock);
+ mutex_lock(&alloc->mutex);
/*
* Make sure the binder_alloc is fully initialized, otherwise we might
* read inconsistent state.
@@ -1007,7 +1007,7 @@ void binder_alloc_print_pages(struct seq_file *m,
lru++;
}
}
- spin_unlock(&alloc->lock);
+ mutex_unlock(&alloc->mutex);
seq_printf(m, " pages: %d:%d:%d\n", active, lru, free);
seq_printf(m, " pages high watermark: %zu\n", alloc->pages_high);
}
@@ -1023,10 +1023,10 @@ int binder_alloc_get_allocated_count(struct binder_alloc *alloc)
struct rb_node *n;
int count = 0;

- spin_lock(&alloc->lock);
+ mutex_lock(&alloc->mutex);
for (n = rb_first(&alloc->allocated_buffers); n != NULL; n = rb_next(n))
count++;
- spin_unlock(&alloc->lock);
+ mutex_unlock(&alloc->mutex);
return count;
}

@@ -1070,8 +1070,8 @@ enum lru_status binder_alloc_free_page(struct list_head *item,
goto err_mmget;
if (!mmap_read_trylock(mm))
goto err_mmap_read_lock_failed;
- if (!spin_trylock(&alloc->lock))
- goto err_get_alloc_lock_failed;
+ if (!mutex_trylock(&alloc->mutex))
+ goto err_get_alloc_mutex_failed;
if (!page->page_ptr)
goto err_page_already_freed;

@@ -1090,7 +1090,7 @@ enum lru_status binder_alloc_free_page(struct list_head *item,
trace_binder_unmap_kernel_end(alloc, index);

list_lru_isolate(lru, item);
- spin_unlock(&alloc->lock);
+ mutex_unlock(&alloc->mutex);
spin_unlock(&lru->lock);

if (vma) {
@@ -1109,8 +1109,8 @@ enum lru_status binder_alloc_free_page(struct list_head *item,

err_invalid_vma:
err_page_already_freed:
- spin_unlock(&alloc->lock);
-err_get_alloc_lock_failed:
+ mutex_unlock(&alloc->mutex);
+err_get_alloc_mutex_failed:
mmap_read_unlock(mm);
err_mmap_read_lock_failed:
mmput_async(mm);
@@ -1145,7 +1145,7 @@ void binder_alloc_init(struct binder_alloc *alloc)
alloc->pid = current->group_leader->pid;
alloc->mm = current->mm;
mmgrab(alloc->mm);
- spin_lock_init(&alloc->lock);
+ mutex_init(&alloc->mutex);
INIT_LIST_HEAD(&alloc->buffers);
}

diff --git a/drivers/android/binder_alloc.h b/drivers/android/binder_alloc.h
index c02c8ebcb466..33c5f971c0a5 100644
--- a/drivers/android/binder_alloc.h
+++ b/drivers/android/binder_alloc.h
@@ -9,7 +9,7 @@
#include <linux/rbtree.h>
#include <linux/list.h>
#include <linux/mm.h>
-#include <linux/spinlock.h>
+#include <linux/rtmutex.h>
#include <linux/vmalloc.h>
#include <linux/slab.h>
#include <linux/list_lru.h>
@@ -72,7 +72,7 @@ struct binder_lru_page {

/**
* struct binder_alloc - per-binder proc state for binder allocator
- * @lock: protects binder_alloc fields
+ * @mutex: protects binder_alloc fields
* @vma: vm_area_struct passed to mmap_handler
* (invariant after mmap)
* @mm: copy of task->mm (invariant after open)
@@ -96,7 +96,7 @@ struct binder_lru_page {
* struct binder_buffer objects used to track the user buffers
*/
struct binder_alloc {
- spinlock_t lock;
+ struct mutex mutex;
struct vm_area_struct *vma;
struct mm_struct *mm;
unsigned long buffer;
@@ -153,9 +153,9 @@ binder_alloc_get_free_async_space(struct binder_alloc *alloc)
{
size_t free_async_space;

- spin_lock(&alloc->lock);
+ mutex_lock(&alloc->mutex);
free_async_space = alloc->free_async_space;
- spin_unlock(&alloc->lock);
+ mutex_unlock(&alloc->mutex);
return free_async_space;
}

--
2.47.0.338.g60cca15819-goog