[PATCH] x86-64: get rid of ARCH_HAVE_XTIME_LOCK (5809f9d4) · Commits · 戴 / test

ARCH_HAVE_XTIME_LOCK is used by x86_64 arch . This arch needs to place a read only copy of xtime_lock into vsyscall page. This read only copy is named __xtime_lock, and xtime_lock is defined in arch/x86_64/kernel/vmlinux.lds.S as an alias. So the declaration of xtime_lock in kernel/timer.c was guarded by ARCH_HAVE_XTIME_LOCK define, defined to true on x86_64. We can get same result with _attribute__((weak)) in the declaration. linker should do the job. Signed-off-by:

Eric Dumazet <dada1@cosmosbay.com> Signed-off-by:

Andi Kleen <ak@suse.de> Cc: Andi Kleen <ak@suse.de> Signed-off-by:

Andrew Morton <akpm@osdl.org>

include/asm-x86_64/vsyscall.h

+0 −5

Original line number	Diff line number	Diff line
		@@ -56,11 +56,6 @@ extern struct vxtime_data vxtime;
		extern int vgetcpu_mode;
		extern struct timezone sys_tz;
		extern int sysctl_vsyscall;
		extern seqlock_t xtime_lock;

		extern int sysctl_vsyscall;

		#define ARCH_HAVE_XTIME_LOCK 1

		#endif /* __KERNEL__ */

include/linux/time.h

+1 −1

Original line number	Diff line number	Diff line
		@@ -90,7 +90,7 @@ static inline struct timespec timespec_sub(struct timespec lhs,

		extern struct timespec xtime;
		extern struct timespec wall_to_monotonic;
		extern seqlock_t xtime_lock;
		extern seqlock_t xtime_lock __attribute__((weak));

		void timekeeping_init(void);

kernel/timer.c

+1 −3

Original line number	Diff line number	Diff line
		@@ -1162,11 +1162,9 @@ static inline void calc_load(unsigned long ticks)
		* This read-write spinlock protects us from races in SMP while
		* playing with xtime and avenrun.
		*/
		#ifndef ARCH_HAVE_XTIME_LOCK
		__cacheline_aligned_in_smp DEFINE_SEQLOCK(xtime_lock);
		__attribute__((weak)) __cacheline_aligned_in_smp DEFINE_SEQLOCK(xtime_lock);

		EXPORT_SYMBOL(xtime_lock);
		#endif

		/*
		* This function runs timers and the timer-tq in bottom half context.

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