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ring_buffer: add paranoid check for buffer page

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If for some strange reason the buffer_page gets bigger, or the page struct
gets smaller, I want to know this ASAP.  The best way is to not let the
kernel compile.

This patch adds code to test the size of the struct buffer_page against the
page struct and will cause compile issues if the buffer_page ever gets bigger
than the page struct.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Steven Rostedt 2008-09-29 23:02:39 -04:00 committed by Ingo Molnar
parent 7a8e76a382
commit a7b1374333
1 changed files with 11 additions and 0 deletions
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11
kernel/trace/ring_buffer.c
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@ -289,6 +289,12 @@ static void rb_free_cpu_buffer(struct ring_buffer_per_cpu *cpu_buffer)
kfree(cpu_buffer);
}
/*
* Causes compile errors if the struct buffer_page gets bigger
* than the struct page.
*/
extern int ring_buffer_page_too_big(void);
/**
* ring_buffer_alloc - allocate a new ring_buffer
* @size: the size in bytes that is needed.
@ -305,6 +311,11 @@ struct ring_buffer *ring_buffer_alloc(unsigned long size, unsigned flags)
int bsize;
int cpu;
/* Paranoid! Optimizes out when all is well */
if (sizeof(struct buffer_page) > sizeof(struct page))
ring_buffer_page_too_big();
/* keep it in its own cache line */
buffer = kzalloc(ALIGN(sizeof(*buffer), cache_line_size()),
GFP_KERNEL);