]> pilppa.com Git - linux-2.6-omap-h63xx.git/commit
ring-buffer: fix alignment problem
authorSteven Rostedt <srostedt@redhat.com>
Mon, 19 Jan 2009 19:32:51 +0000 (14:32 -0500)
committerIngo Molnar <mingo@elte.hu>
Tue, 20 Jan 2009 12:09:06 +0000 (13:09 +0100)
commit082605de5f82eb692cc90f7fda071cc01bb5ac34
treef3e2536d840dff5f15e25ee609ab37a645f8fd9a
parent1de9e8e70f5acc441550ca75433563d91b269bbe
ring-buffer: fix alignment problem

Impact: fix to allow some archs to use the ring buffer

Commits in the ring buffer are checked by pointer arithmetic.
If the calculation is incorrect, then the commits will never take
place and the buffer will simply fill up and report an error.

Each page in the ring buffer has a small header:

struct buffer_data_page {
u64 time_stamp;
local_t commit;
unsigned char data[];
};

Unfortuntely, some of the calculations used sizeof(struct buffer_data_page)
to know the size of the header. But this is incorrect on some archs,
where sizeof(struct buffer_data_page) does not equal
offsetof(struct buffer_data_page, data), and on those archs, the commits
are never processed.

This patch replaces the sizeof with offsetof.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
kernel/trace/ring_buffer.c