diff options
Diffstat (limited to 'kernel/trace/ring_buffer.c')
| -rw-r--r-- | kernel/trace/ring_buffer.c | 28 |
1 files changed, 18 insertions, 10 deletions
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index 3a0c7ed0e93f..d59b6a328b7f 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -476,6 +476,7 @@ struct rb_time_struct { local_t cnt; local_t top; local_t bottom; + local_t msb; }; #else #include <asm/local64.h> @@ -577,7 +578,6 @@ struct ring_buffer_iter { * For the ring buffer, 64 bit required operations for the time is * the following: * - * - Only need 59 bits (uses 60 to make it even). * - Reads may fail if it interrupted a modification of the time stamp. * It will succeed if it did not interrupt another write even if * the read itself is interrupted by a write. @@ -602,6 +602,7 @@ struct ring_buffer_iter { */ #define RB_TIME_SHIFT 30 #define RB_TIME_VAL_MASK ((1 << RB_TIME_SHIFT) - 1) +#define RB_TIME_MSB_SHIFT 60 static inline int rb_time_cnt(unsigned long val) { @@ -621,7 +622,7 @@ static inline u64 rb_time_val(unsigned long top, unsigned long bottom) static inline bool __rb_time_read(rb_time_t *t, u64 *ret, unsigned long *cnt) { - unsigned long top, bottom; + unsigned long top, bottom, msb; unsigned long c; /* @@ -633,6 +634,7 @@ static inline bool __rb_time_read(rb_time_t *t, u64 *ret, unsigned long *cnt) c = local_read(&t->cnt); top = local_read(&t->top); bottom = local_read(&t->bottom); + msb = local_read(&t->msb); } while (c != local_read(&t->cnt)); *cnt = rb_time_cnt(top); @@ -641,7 +643,8 @@ static inline bool __rb_time_read(rb_time_t *t, u64 *ret, unsigned long *cnt) if (*cnt != rb_time_cnt(bottom)) return false; - *ret = rb_time_val(top, bottom); + /* The shift to msb will lose its cnt bits */ + *ret = rb_time_val(top, bottom) | ((u64)msb << RB_TIME_MSB_SHIFT); return true; } @@ -657,10 +660,12 @@ static inline unsigned long rb_time_val_cnt(unsigned long val, unsigned long cnt return (val & RB_TIME_VAL_MASK) | ((cnt & 3) << RB_TIME_SHIFT); } -static inline void rb_time_split(u64 val, unsigned long *top, unsigned long *bottom) +static inline void rb_time_split(u64 val, unsigned long *top, unsigned long *bottom, + unsigned long *msb) { *top = (unsigned long)((val >> RB_TIME_SHIFT) & RB_TIME_VAL_MASK); *bottom = (unsigned long)(val & RB_TIME_VAL_MASK); + *msb = (unsigned long)(val >> RB_TIME_MSB_SHIFT); } static inline void rb_time_val_set(local_t *t, unsigned long val, unsigned long cnt) @@ -671,15 +676,16 @@ static inline void rb_time_val_set(local_t *t, unsigned long val, unsigned long static void rb_time_set(rb_time_t *t, u64 val) { - unsigned long cnt, top, bottom; + unsigned long cnt, top, bottom, msb; - rb_time_split(val, &top, &bottom); + rb_time_split(val, &top, &bottom, &msb); /* Writes always succeed with a valid number even if it gets interrupted. */ do { cnt = local_inc_return(&t->cnt); rb_time_val_set(&t->top, top, cnt); rb_time_val_set(&t->bottom, bottom, cnt); + rb_time_val_set(&t->msb, val >> RB_TIME_MSB_SHIFT, cnt); } while (cnt != local_read(&t->cnt)); } @@ -694,8 +700,8 @@ rb_time_read_cmpxchg(local_t *l, unsigned long expect, unsigned long set) static int rb_time_cmpxchg(rb_time_t *t, u64 expect, u64 set) { - unsigned long cnt, top, bottom; - unsigned long cnt2, top2, bottom2; + unsigned long cnt, top, bottom, msb; + unsigned long cnt2, top2, bottom2, msb2; u64 val; /* The cmpxchg always fails if it interrupted an update */ @@ -711,16 +717,18 @@ static int rb_time_cmpxchg(rb_time_t *t, u64 expect, u64 set) cnt2 = cnt + 1; - rb_time_split(val, &top, &bottom); + rb_time_split(val, &top, &bottom, &msb); top = rb_time_val_cnt(top, cnt); bottom = rb_time_val_cnt(bottom, cnt); - rb_time_split(set, &top2, &bottom2); + rb_time_split(set, &top2, &bottom2, &msb2); top2 = rb_time_val_cnt(top2, cnt2); bottom2 = rb_time_val_cnt(bottom2, cnt2); if (!rb_time_read_cmpxchg(&t->cnt, cnt, cnt2)) return false; + if (!rb_time_read_cmpxchg(&t->msb, msb, msb2)) + return false; if (!rb_time_read_cmpxchg(&t->top, top, top2)) return false; if (!rb_time_read_cmpxchg(&t->bottom, bottom, bottom2)) |