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Commit 2dd887e3 authored by Stefano Stabellini's avatar Stefano Stabellini Committed by David Vrabel
Browse files

xen/time: use READ_ONCE 



Use READ_ONCE through the code, rather than explicit barriers.

Suggested-by: default avatarMark Rutland <mark.rutland@arm.com>
Signed-off-by: default avatarStefano Stabellini <stefano.stabellini@eu.citrix.com>
Signed-off-by: default avatarDavid Vrabel <david.vrabel@citrix.com>
parent 187b26a9

drivers/xen/time.c

+7 −10
Original line number Diff line number Diff line
@@ -25,7 +25,7 @@ static u64 get64(const u64 *p) 


	if (BITS_PER_LONG < 64) {

		u32 *p32 = (u32 *)p;

		u32 h, l;

		u32 h, l, h2;



		/*

		 * Read high then low, and then make sure high is
@@ -34,15 +34,14 @@ static u64 get64(const u64 *p) 
		 * XXX some clean way to make this endian-proof?

		 */

		do {

			h = p32[1];

			barrier();

			l = p32[0];

			barrier();

		} while (p32[1] != h);

			h = READ_ONCE(p32[1]);

			l = READ_ONCE(p32[0]);

			h2 = READ_ONCE(p32[1]);

		} while(h2 != h);



		ret = (((u64)h) << 32) | l;

	} else

		ret = *p;

		ret = READ_ONCE(*p);



	return ret;

}
@@ -66,9 +65,7 @@ void xen_get_runstate_snapshot(struct vcpu_runstate_info *res) 
	 */

	do {

		state_time = get64(&state->state_entry_time);

		barrier();

		*res = *state;

		barrier();

		*res = READ_ONCE(*state);

	} while (get64(&state->state_entry_time) != state_time);

}