Commit 74e2afc6 authored by Qiujun Huang's avatar Qiujun Huang Committed by Steven Rostedt (VMware)
Browse files

ring-buffer: Add rb_check_bpage in __rb_allocate_pages 

It may be better to check each page is aligned by 4 bytes. The 2
least significant bits of the address will be used as flags.

Link: https://lkml.kernel.org/r/20201015113842.2921-1-hqjagain@gmail.com



Signed-off-by: default avatarQiujun Huang <hqjagain@gmail.com>
Signed-off-by: default avatarSteven Rostedt (VMware) <rostedt@goodmis.org>
parent 82db909e

kernel/trace/ring_buffer.c

+11 −8
Original line number Diff line number Diff line
@@ -1423,7 +1423,8 @@ static int rb_check_pages(struct ring_buffer_per_cpu *cpu_buffer) 
	return 0;

}



static int __rb_allocate_pages(long nr_pages, struct list_head *pages, int cpu)

static int __rb_allocate_pages(struct ring_buffer_per_cpu *cpu_buffer,

		long nr_pages, struct list_head *pages)

{

	struct buffer_page *bpage, *tmp;

	bool user_thread = current->mm != NULL;
@@ -1463,13 +1464,15 @@ static int __rb_allocate_pages(long nr_pages, struct list_head *pages, int cpu) 
		struct page *page;



		bpage = kzalloc_node(ALIGN(sizeof(*bpage), cache_line_size()),

				    mflags, cpu_to_node(cpu));

				    mflags, cpu_to_node(cpu_buffer->cpu));

		if (!bpage)

			goto free_pages;



		rb_check_bpage(cpu_buffer, bpage);



		list_add(&bpage->list, pages);



		page = alloc_pages_node(cpu_to_node(cpu), mflags, 0);

		page = alloc_pages_node(cpu_to_node(cpu_buffer->cpu), mflags, 0);

		if (!page)

			goto free_pages;

		bpage->page = page_address(page);
@@ -1501,7 +1504,7 @@ static int rb_allocate_pages(struct ring_buffer_per_cpu *cpu_buffer, 


	WARN_ON(!nr_pages);



	if (__rb_allocate_pages(nr_pages, &pages, cpu_buffer->cpu))

	if (__rb_allocate_pages(cpu_buffer, nr_pages, &pages))

		return -ENOMEM;



	/*
@@ -2008,8 +2011,8 @@ int ring_buffer_resize(struct trace_buffer *buffer, unsigned long size, 
			 * allocated without receiving ENOMEM

			 */

			INIT_LIST_HEAD(&cpu_buffer->new_pages);

			if (__rb_allocate_pages(cpu_buffer->nr_pages_to_update,

						&cpu_buffer->new_pages, cpu)) {

			if (__rb_allocate_pages(cpu_buffer, cpu_buffer->nr_pages_to_update,

						&cpu_buffer->new_pages)) {

				/* not enough memory for new pages */

				err = -ENOMEM;

				goto out_err;
@@ -2074,8 +2077,8 @@ int ring_buffer_resize(struct trace_buffer *buffer, unsigned long size, 


		INIT_LIST_HEAD(&cpu_buffer->new_pages);

		if (cpu_buffer->nr_pages_to_update > 0 &&

			__rb_allocate_pages(cpu_buffer->nr_pages_to_update,

					    &cpu_buffer->new_pages, cpu_id)) {

			__rb_allocate_pages(cpu_buffer, cpu_buffer->nr_pages_to_update,

					    &cpu_buffer->new_pages)) {

			err = -ENOMEM;

			goto out_err;

		}