Commit 60830868 authored Jul 22, 2014 by Aaro Koskinen Committed by Ralf Baechle Aug 19, 2014

MIPS: OCTEON: make get_system_type() thread-safe



get_system_type() is not thread-safe on OCTEON. It uses static data,
also more dangerous issue is that it's calling cvmx_fuse_read_byte()
every time without any synchronization. Currently it's possible to get
processes stuck looping forever in kernel simply by launching multiple
readers of /proc/cpuinfo:

	(while true; do cat /proc/cpuinfo > /dev/null; done) &
	(while true; do cat /proc/cpuinfo > /dev/null; done) &
	...

Fix by initializing the system type string only once during the early
boot.

Signed-off-by: Aaro Koskinen <aaro.koskinen@nsn.com>
Cc: stable@vger.kernel.org
Reviewed-by: Markos Chandras <markos.chandras@imgtec.com>
Patchwork: http://patchwork.linux-mips.org/patch/7437/


Signed-off-by: James Hogan <james.hogan@imgtec.com>

parent 6521d9a4

arch/mips/cavium-octeon/setup.c

+13 −5

Original line number	Diff line number	Diff line
		@@ -457,6 +457,18 @@ static void octeon_halt(void)
		octeon_kill_core(NULL);
		}

		static char __read_mostly octeon_system_type[80];

		static int __init init_octeon_system_type(void)
		{
		snprintf(octeon_system_type, sizeof(octeon_system_type), "%s (%s)",
		cvmx_board_type_to_string(octeon_bootinfo->board_type),
		octeon_model_get_string(read_c0_prid()));

		return 0;
		}
		early_initcall(init_octeon_system_type);

		/**
		* Return a string representing the system type
		*
		@@ -464,11 +476,7 @@ static void octeon_halt(void)
		*/
		const char *octeon_board_type_string(void)
		{
		static char name[80];
		sprintf(name, "%s (%s)",
		cvmx_board_type_to_string(octeon_bootinfo->board_type),
		octeon_model_get_string(read_c0_prid()));
		return name;
		return octeon_system_type;
		}

		const char *get_system_type(void)