ring_buffer: add paranoid check for buffer page (a7b13743) · Commits · 戴 / test

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>

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);

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