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ring_buffer: allocate buffer page pointer

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The current method of overlaying the page frame as the buffer page pointer
can be very dangerous and limits our ability to do other things with
a page from the buffer, like send it off to disk.

This patch allocates the buffer_page instead of overlaying the page's
page frame. The use of the buffer_page has hardly changed due to this.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Steven Rostedt 2008-10-01 11:14:54 -04:00 committed by Ingo Molnar
parent 7104f300c5
commit e4c2ce82ca
1 changed files with 32 additions and 22 deletions
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48
kernel/trace/ring_buffer.c
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@ -115,16 +115,10 @@ void *ring_buffer_event_data(struct ring_buffer_event *event)
* Thanks to Peter Zijlstra for suggesting this idea.
*/
struct buffer_page {
union {
struct {
unsigned long flags; /* mandatory */
atomic_t _count; /* mandatory */
u64 time_stamp; /* page time stamp */
unsigned size; /* size of page data */
struct list_head list; /* list of free pages */
};
struct page page;
};
void *page; /* Actual data page */
};
/*
@ -133,9 +127,9 @@ struct buffer_page {
*/
static inline void free_buffer_page(struct buffer_page *bpage)
{
reset_page_mapcount(&bpage->page);
bpage->page.mapping = NULL;
__free_page(&bpage->page);
if (bpage->page)
__free_page(bpage->page);
kfree(bpage);
}
/*
@ -237,11 +231,16 @@ static int rb_allocate_pages(struct ring_buffer_per_cpu *cpu_buffer,
unsigned i;
for (i = 0; i < nr_pages; i++) {
page = kzalloc_node(ALIGN(sizeof(*page), cache_line_size()),
GFP_KERNEL, cpu_to_node(cpu));
if (!page)
goto free_pages;
list_add(&page->list, &pages);
addr = __get_free_page(GFP_KERNEL);
if (!addr)
goto free_pages;
page = (struct buffer_page *)virt_to_page(addr);
list_add(&page->list, &pages);
page->page = (void *)addr;
}
list_splice(&pages, head);
@ -262,6 +261,7 @@ static struct ring_buffer_per_cpu *
rb_allocate_cpu_buffer(struct ring_buffer *buffer, int cpu)
{
struct ring_buffer_per_cpu *cpu_buffer;
struct buffer_page *page;
unsigned long addr;
int ret;
@ -275,10 +275,17 @@ rb_allocate_cpu_buffer(struct ring_buffer *buffer, int cpu)
spin_lock_init(&cpu_buffer->lock);
INIT_LIST_HEAD(&cpu_buffer->pages);
page = kzalloc_node(ALIGN(sizeof(*page), cache_line_size()),
GFP_KERNEL, cpu_to_node(cpu));
if (!page)
goto fail_free_buffer;
cpu_buffer->reader_page = page;
addr = __get_free_page(GFP_KERNEL);
if (!addr)
goto fail_free_buffer;
cpu_buffer->reader_page = (struct buffer_page *)virt_to_page(addr);
goto fail_free_reader;
page->page = (void *)addr;
INIT_LIST_HEAD(&cpu_buffer->reader_page->list);
cpu_buffer->reader_page->size = 0;
@ -523,11 +530,16 @@ int ring_buffer_resize(struct ring_buffer *buffer, unsigned long size)
for_each_buffer_cpu(buffer, cpu) {
for (i = 0; i < new_pages; i++) {
page = kzalloc_node(ALIGN(sizeof(*page),
cache_line_size()),
GFP_KERNEL, cpu_to_node(cpu));
if (!page)
goto free_pages;
list_add(&page->list, &pages);
addr = __get_free_page(GFP_KERNEL);
if (!addr)
goto free_pages;
page = (struct buffer_page *)virt_to_page(addr);
list_add(&page->list, &pages);
page->page = (void *)addr;
}
}
@ -567,9 +579,7 @@ static inline int rb_null_event(struct ring_buffer_event *event)
static inline void *rb_page_index(struct buffer_page *page, unsigned index)
{
void *addr = page_address(&page->page);
return addr + index;
return page->page + index;
}
static inline struct ring_buffer_event *