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Commit a7b13743 authored by Steven Rostedt's avatar Steven Rostedt Committed by Ingo Molnar
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ring_buffer: add paranoid check for buffer page 



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: default avatarSteven Rostedt <srostedt@redhat.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 7a8e76a3

kernel/trace/ring_buffer.c

+11 −0
Original line number Diff line number Diff line
@@ -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);