linux/arch/x86/include/asm/io_bitmap.h

/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _ASM_X86_IOBITMAP_H
#define _ASM_X86_IOBITMAP_H

#include <asm/processor.h>

struct io_bitmap {
	u64		sequence;
	/* The maximum number of bytes to copy so all zero bits are covered */
	unsigned int	max;
	unsigned long	bitmap[IO_BITMAP_LONGS];
};

#endif
x86/ioperm: Move iobitmap data into a struct No point in having all the data in thread_struct, especially as upcoming changes add more. Make the bitmap in the new struct accessible as array of longs and as array of characters via a union, so both the bitmap functions and the update logic can avoid type casts. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> 2019-11-11 22:03:21 +00:00			`/* SPDX-License-Identifier: GPL-2.0 */`
			`#ifndef _ASM_X86_IOBITMAP_H`
			`#define _ASM_X86_IOBITMAP_H`

			`#include <asm/processor.h>`

			`struct io_bitmap {`
x86/ioperm: Add bitmap sequence number Add a globally unique sequence number which is incremented when ioperm() is changing the I/O bitmap of a task. Store the new sequence number in the io_bitmap structure and compare it with the sequence number of the I/O bitmap which was last loaded on a CPU. Only update the bitmap if the sequence is different. That should further reduce the overhead of I/O bitmap scheduling when there are only a few I/O bitmap users on the system. The 64bit sequence counter is sufficient. A wraparound of the sequence counter assuming an ioperm() call every nanosecond would require about 584 years of uptime. Suggested-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> 2019-11-11 22:03:22 +00:00			`u64 sequence;`
x86/ioperm: Move iobitmap data into a struct No point in having all the data in thread_struct, especially as upcoming changes add more. Make the bitmap in the new struct accessible as array of longs and as array of characters via a union, so both the bitmap functions and the update logic can avoid type casts. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> 2019-11-11 22:03:21 +00:00			`/* The maximum number of bytes to copy so all zero bits are covered */`
			`unsigned int max;`
			`unsigned long bitmap[IO_BITMAP_LONGS];`
			`};`

			`#endif`