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binder: malloc new_buffer outside of locks

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Preallocate new_buffer before acquiring the alloc->mutex and hand it
down to binder_alloc_new_buf_locked(). The new buffer will be used in
the vast majority of requests (measured at 98.2% in field data). The
buffer is discarded otherwise. This change is required in preparation
for transitioning alloc->mutex into a spinlock in subsequent commits.

Signed-off-by: Carlos Llamas <cmllamas@google.com>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Link: https://lore.kernel.org/r/20231201172212.1813387-18-cmllamas@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Carlos Llamas 2023-12-01 17:21:46 +00:00 committed by Greg Kroah-Hartman
parent ea2735ce19
commit c7ac30fad1
1 changed files with 23 additions and 21 deletions
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44
drivers/android/binder_alloc.c
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@ -395,24 +395,27 @@ static bool debug_low_async_space_locked(struct binder_alloc *alloc)
return false;
}
/* Callers preallocate @new_buffer, it is freed by this function if unused */
static struct binder_buffer *binder_alloc_new_buf_locked(
struct binder_alloc *alloc,
struct binder_buffer *new_buffer,
size_t size,
int is_async)
{
struct rb_node *n = alloc->free_buffers.rb_node;
struct binder_buffer *buffer;
size_t buffer_size;
struct rb_node *best_fit = NULL;
struct binder_buffer *buffer;
unsigned long has_page_addr;
unsigned long end_page_addr;
size_t buffer_size;
int ret;
if (is_async && alloc->free_async_space < size) {
binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
"%d: binder_alloc_buf size %zd failed, no async space left\n",
alloc->pid, size);
return ERR_PTR(-ENOSPC);
buffer = ERR_PTR(-ENOSPC);
goto out;
}
while (n) {
@ -436,7 +439,8 @@ static struct binder_buffer *binder_alloc_new_buf_locked(
"%d: binder_alloc_buf size %zd failed, no address space\n",
alloc->pid, size);
debug_no_space_locked(alloc);
return ERR_PTR(-ENOSPC);
buffer = ERR_PTR(-ENOSPC);
goto out;
}
if (n == NULL) {
@ -455,22 +459,17 @@ static struct binder_buffer *binder_alloc_new_buf_locked(
end_page_addr = has_page_addr;
ret = binder_allocate_page_range(alloc, PAGE_ALIGN(buffer->user_data),
end_page_addr);
if (ret)
return ERR_PTR(ret);
if (ret) {
buffer = ERR_PTR(ret);
goto out;
}
if (buffer_size != size) {
struct binder_buffer *new_buffer;
new_buffer = kzalloc(sizeof(*buffer), GFP_KERNEL);
if (!new_buffer) {
pr_err("%s: %d failed to alloc new buffer struct\n",
__func__, alloc->pid);
goto err_alloc_buf_struct_failed;
}
new_buffer->user_data = buffer->user_data + size;
list_add(&new_buffer->entry, &buffer->entry);
new_buffer->free = 1;
binder_insert_free_buffer(alloc, new_buffer);
new_buffer = NULL;
}
rb_erase(best_fit, &alloc->free_buffers);
@ -491,12 +490,10 @@ static struct binder_buffer *binder_alloc_new_buf_locked(
buffer->oneway_spam_suspect = true;
}
out:
/* Discard possibly unused new_buffer */
kfree(new_buffer);
return buffer;
err_alloc_buf_struct_failed:
binder_free_page_range(alloc, PAGE_ALIGN(buffer->user_data),
end_page_addr);
return ERR_PTR(-ENOMEM);
}
/* Calculate the sanitized total size, returns 0 for invalid request */
@ -542,7 +539,7 @@ struct binder_buffer *binder_alloc_new_buf(struct binder_alloc *alloc,
size_t extra_buffers_size,
int is_async)
{
struct binder_buffer *buffer;
struct binder_buffer *buffer, *next;
size_t size;
/* Check binder_alloc is fully initialized */
@ -562,8 +559,13 @@ struct binder_buffer *binder_alloc_new_buf(struct binder_alloc *alloc,
return ERR_PTR(-EINVAL);
}
/* Preallocate the next buffer */
next = kzalloc(sizeof(*next), GFP_KERNEL);
if (!next)
return ERR_PTR(-ENOMEM);
mutex_lock(&alloc->mutex);
buffer = binder_alloc_new_buf_locked(alloc, size, is_async);
buffer = binder_alloc_new_buf_locked(alloc, next, size, is_async);
if (IS_ERR(buffer)) {
mutex_unlock(&alloc->mutex);
goto out;