linux-stable/arch/sparc/include/asm/vvar.h
Peter Zijlstra 0cd39f4600 locking/seqlock, headers: Untangle the spaghetti monster
By using lockdep_assert_*() from seqlock.h, the spaghetti monster
attacked.

Attack back by reducing seqlock.h dependencies from two key high level headers:

 - <linux/seqlock.h>:               -Remove <linux/ww_mutex.h>
 - <linux/time.h>:                  -Remove <linux/seqlock.h>
 - <linux/sched.h>:                 +Add    <linux/seqlock.h>

The price was to add it to sched.h ...

Core header fallout, we add direct header dependencies instead of gaining them
parasitically from higher level headers:

 - <linux/dynamic_queue_limits.h>:  +Add <asm/bug.h>
 - <linux/hrtimer.h>:               +Add <linux/seqlock.h>
 - <linux/ktime.h>:                 +Add <asm/bug.h>
 - <linux/lockdep.h>:               +Add <linux/smp.h>
 - <linux/sched.h>:                 +Add <linux/seqlock.h>
 - <linux/videodev2.h>:             +Add <linux/kernel.h>

Arch headers fallout:

 - PARISC: <asm/timex.h>:           +Add <asm/special_insns.h>
 - SH:     <asm/io.h>:              +Add <asm/page.h>
 - SPARC:  <asm/timer_64.h>:        +Add <uapi/asm/asi.h>
 - SPARC:  <asm/vvar.h>:            +Add <asm/processor.h>, <asm/barrier.h>
                                    -Remove <linux/seqlock.h>
 - X86:    <asm/fixmap.h>:          +Add <asm/pgtable_types.h>
                                    -Remove <asm/acpi.h>

There's also a bunch of parasitic header dependency fallout in .c files, not listed
separately.

[ mingo: Extended the changelog, split up & fixed the original patch. ]

Co-developed-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20200804133438.GK2674@hirez.programming.kicks-ass.net
2020-08-06 16:13:13 +02:00

75 lines
1.5 KiB
C

/*
* Copyright (c) 2017 Oracle and/or its affiliates. All rights reserved.
*/
#ifndef _ASM_SPARC_VVAR_DATA_H
#define _ASM_SPARC_VVAR_DATA_H
#include <asm/clocksource.h>
#include <asm/processor.h>
#include <asm/barrier.h>
#include <linux/time.h>
#include <linux/types.h>
struct vvar_data {
unsigned int seq;
int vclock_mode;
struct { /* extract of a clocksource struct */
u64 cycle_last;
u64 mask;
int mult;
int shift;
} clock;
/* open coded 'struct timespec' */
u64 wall_time_sec;
u64 wall_time_snsec;
u64 monotonic_time_snsec;
u64 monotonic_time_sec;
u64 monotonic_time_coarse_sec;
u64 monotonic_time_coarse_nsec;
u64 wall_time_coarse_sec;
u64 wall_time_coarse_nsec;
int tz_minuteswest;
int tz_dsttime;
};
extern struct vvar_data *vvar_data;
extern int vdso_fix_stick;
static inline unsigned int vvar_read_begin(const struct vvar_data *s)
{
unsigned int ret;
repeat:
ret = READ_ONCE(s->seq);
if (unlikely(ret & 1)) {
cpu_relax();
goto repeat;
}
smp_rmb(); /* Finish all reads before we return seq */
return ret;
}
static inline int vvar_read_retry(const struct vvar_data *s,
unsigned int start)
{
smp_rmb(); /* Finish all reads before checking the value of seq */
return unlikely(s->seq != start);
}
static inline void vvar_write_begin(struct vvar_data *s)
{
++s->seq;
smp_wmb(); /* Makes sure that increment of seq is reflected */
}
static inline void vvar_write_end(struct vvar_data *s)
{
smp_wmb(); /* Makes the value of seq current before we increment */
++s->seq;
}
#endif /* _ASM_SPARC_VVAR_DATA_H */