On Sat, Feb 24, 2018 at 01:32:50PM +0800, Boqun Feng wrote: [...] > > I also reorder bit number for each kind of dependency, so that we have a > simple __calc_dep_bit(), see the following: > > /* > * DEP_*_BIT in lock_list::dep > * > * For dependency @prev -> @next: > * > * RR: both @prev and @next are recursive read locks, i.e. ->read == > 2. > * RN: @prev is recursive and @next is non-recursive. > * NR: @prev is a not recursive and @next is recursive. > * NN: both @prev and @next are non-recursive. > * > * Note that we define the value of DEP_*_BITs so that: > * bit0 is prev->read != 2 > * bit1 is next->read != 2 > */ > #define DEP_RR_BIT 0 > #define DEP_RN_BIT 1 > #define DEP_NR_BIT 2
Oops, to make the following __cal_dep_bit() works, we should have:
#define DEP_NR_BIT 1
#define DEP_RN_BIT 2
instead.
Regards,
Boqun
> #define DEP_NN_BIT 3
>
> #define DEP_RR_MASK (1U << (DEP_RR_BIT))
> #define DEP_RN_MASK (1U << (DEP_RN_BIT))
> #define DEP_NR_MASK (1U << (DEP_NR_BIT))
> #define DEP_NN_MASK (1U << (DEP_NN_BIT))
>
> static inline unsigned int
> __calc_dep_bit(struct held_lock *prev, struct held_lock *next)
> {
> return (prev->read != 2) + ((next->read != 2) << 1)
> }
>
> static inline u8 calc_dep(struct held_lock *prev, struct held_lock
> *next)
> {
> return 1U << __calc_dep_bit(prev, next);
> }
>
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