[PATCH] ring-buffer: Add rb_check_bpage in __rb_allocate_pages

From: Qiujun Huang
Date: Wed Oct 14 2020 - 11:16:27 EST


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.

Signed-off-by: Qiujun Huang <hqjagain@xxxxxxxxx>
---
kernel/trace/ring_buffer.c | 11 +++++++----
1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index 93ef0ab6ea20..9dec7d58b177 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -1420,7 +1420,8 @@ 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, int cpu)
{
struct buffer_page *bpage, *tmp;
bool user_thread = current->mm != NULL;
@@ -1464,6 +1465,8 @@ static int __rb_allocate_pages(long nr_pages, struct list_head *pages, int 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);
@@ -1498,7 +1501,7 @@ 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, cpu_buffer->cpu))
return -ENOMEM;

/*
@@ -2007,7 +2010,7 @@ 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,
+ if (__rb_allocate_pages(cpu_buffer, cpu_buffer->nr_pages_to_update,
&cpu_buffer->new_pages, cpu)) {
/* not enough memory for new pages */
err = -ENOMEM;
@@ -2073,7 +2076,7 @@ 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,
+ __rb_allocate_pages(cpu_buffer, cpu_buffer->nr_pages_to_update,
&cpu_buffer->new_pages, cpu_id)) {
err = -ENOMEM;
goto out_err;
--
2.17.1