Messages in this thread | | | Date | Tue, 22 Mar 2022 10:48:32 -0700 (PDT) | Subject | Re: [PATCH] csky: Move to generic ticket-spinlock | From | Palmer Dabbelt <> |
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On Fri, 18 Mar 2022 21:01:49 PDT (-0700), guoren@kernel.org wrote: > Hi Palmer, > > On Sat, Mar 19, 2022 at 6:48 AM Palmer Dabbelt <palmer@rivosinc.com> wrote: >> >> On Fri, 18 Mar 2022 01:34:21 PDT (-0700), guoren@kernel.org wrote: >> > From: Guo Ren <guoren@linux.alibaba.com> >> > >> > There is no benefit from custom implementation for ticket-spinlock, >> > so move to generic ticket-spinlock for easy maintenance. >> > >> > Signed-off-by: Guo Ren <guoren@linux.alibaba.com> >> > Cc: Palmer Dabbelt <palmer@rivosinc.com> >> >> Thanks, one less port to look at ;) >> >> Looks like there were a few comments on the v1, and I wasn't going to >> target this at the upcoming merge window anyway because I wanted to give > Agree, we needn't so hurry. > >> the various RISC-V vendors time to test stuff. LMK if you want me to >> add this to the others, but I was planning on posting a stable tag >> either way so no big deal on my end. > Yes, I hope csky's could be in the series. And I updated V2 with > Arnd's suggestion, please have a look: > https://lore.kernel.org/linux-arch/20220319035457.2214979-1-guoren@kernel.org/T/#t
Thanks, I'll include the csky stuff next time I re-spin this.
Looks like there's been some other comments from folks that didn't make your v2, most notably the SOB lines which makes this a bit funny. I'm also not sure I like merging the two RISC-V patches together, as they'd be nice to be able to test on their own.
I'll go poke around with this some once I'm a bit father into the merge window. I think we can both keep Arnd's generic header idea and let folks mix/match spin/rw lock flavors, which might also help with some of the other ports.
> >> >> > --- >> > arch/csky/include/asm/Kbuild | 2 + >> > arch/csky/include/asm/spinlock.h | 82 +------------------------- >> > arch/csky/include/asm/spinlock_types.h | 20 +------ >> > 3 files changed, 4 insertions(+), 100 deletions(-) >> > >> > diff --git a/arch/csky/include/asm/Kbuild b/arch/csky/include/asm/Kbuild >> > index 904a18a818be..d94434288c31 100644 >> > --- a/arch/csky/include/asm/Kbuild >> > +++ b/arch/csky/include/asm/Kbuild >> > @@ -3,6 +3,8 @@ generic-y += asm-offsets.h >> > generic-y += extable.h >> > generic-y += gpio.h >> > generic-y += kvm_para.h >> > +generic-y += ticket-lock.h >> > +generic-y += ticket-lock-types.h >> > generic-y += qrwlock.h >> > generic-y += user.h >> > generic-y += vmlinux.lds.h >> > diff --git a/arch/csky/include/asm/spinlock.h b/arch/csky/include/asm/spinlock.h >> > index 69f5aa249c5f..8bc179ba0d8d 100644 >> > --- a/arch/csky/include/asm/spinlock.h >> > +++ b/arch/csky/include/asm/spinlock.h >> > @@ -3,87 +3,7 @@ >> > #ifndef __ASM_CSKY_SPINLOCK_H >> > #define __ASM_CSKY_SPINLOCK_H >> > >> > -#include <linux/spinlock_types.h> >> > -#include <asm/barrier.h> >> > - >> > -/* >> > - * Ticket-based spin-locking. >> > - */ >> > -static inline void arch_spin_lock(arch_spinlock_t *lock) >> > -{ >> > - arch_spinlock_t lockval; >> > - u32 ticket_next = 1 << TICKET_NEXT; >> > - u32 *p = &lock->lock; >> > - u32 tmp; >> > - >> > - asm volatile ( >> > - "1: ldex.w %0, (%2) \n" >> > - " mov %1, %0 \n" >> > - " add %0, %3 \n" >> > - " stex.w %0, (%2) \n" >> > - " bez %0, 1b \n" >> > - : "=&r" (tmp), "=&r" (lockval) >> > - : "r"(p), "r"(ticket_next) >> > - : "cc"); >> > - >> > - while (lockval.tickets.next != lockval.tickets.owner) >> > - lockval.tickets.owner = READ_ONCE(lock->tickets.owner); >> > - >> > - smp_mb(); >> > -} >> > - >> > -static inline int arch_spin_trylock(arch_spinlock_t *lock) >> > -{ >> > - u32 tmp, contended, res; >> > - u32 ticket_next = 1 << TICKET_NEXT; >> > - u32 *p = &lock->lock; >> > - >> > - do { >> > - asm volatile ( >> > - " ldex.w %0, (%3) \n" >> > - " movi %2, 1 \n" >> > - " rotli %1, %0, 16 \n" >> > - " cmpne %1, %0 \n" >> > - " bt 1f \n" >> > - " movi %2, 0 \n" >> > - " add %0, %0, %4 \n" >> > - " stex.w %0, (%3) \n" >> > - "1: \n" >> > - : "=&r" (res), "=&r" (tmp), "=&r" (contended) >> > - : "r"(p), "r"(ticket_next) >> > - : "cc"); >> > - } while (!res); >> > - >> > - if (!contended) >> > - smp_mb(); >> > - >> > - return !contended; >> > -} >> > - >> > -static inline void arch_spin_unlock(arch_spinlock_t *lock) >> > -{ >> > - smp_mb(); >> > - WRITE_ONCE(lock->tickets.owner, lock->tickets.owner + 1); >> > -} >> > - >> > -static inline int arch_spin_value_unlocked(arch_spinlock_t lock) >> > -{ >> > - return lock.tickets.owner == lock.tickets.next; >> > -} >> > - >> > -static inline int arch_spin_is_locked(arch_spinlock_t *lock) >> > -{ >> > - return !arch_spin_value_unlocked(READ_ONCE(*lock)); >> > -} >> > - >> > -static inline int arch_spin_is_contended(arch_spinlock_t *lock) >> > -{ >> > - struct __raw_tickets tickets = READ_ONCE(lock->tickets); >> > - >> > - return (tickets.next - tickets.owner) > 1; >> > -} >> > -#define arch_spin_is_contended arch_spin_is_contended >> > - >> > +#include <asm/ticket-lock.h> >> > #include <asm/qrwlock.h> >> > >> > #endif /* __ASM_CSKY_SPINLOCK_H */ >> > diff --git a/arch/csky/include/asm/spinlock_types.h b/arch/csky/include/asm/spinlock_types.h >> > index db87a12c3827..0bb7f6022a3b 100644 >> > --- a/arch/csky/include/asm/spinlock_types.h >> > +++ b/arch/csky/include/asm/spinlock_types.h >> > @@ -3,25 +3,7 @@ >> > #ifndef __ASM_CSKY_SPINLOCK_TYPES_H >> > #define __ASM_CSKY_SPINLOCK_TYPES_H >> > >> > -#ifndef __LINUX_SPINLOCK_TYPES_RAW_H >> > -# error "please don't include this file directly" >> > -#endif >> > - >> > -#define TICKET_NEXT 16 >> > - >> > -typedef struct { >> > - union { >> > - u32 lock; >> > - struct __raw_tickets { >> > - /* little endian */ >> > - u16 owner; >> > - u16 next; >> > - } tickets; >> > - }; >> > -} arch_spinlock_t; >> > - >> > -#define __ARCH_SPIN_LOCK_UNLOCKED { { 0 } } >> > - >> > +#include <asm/ticket-lock-types.h> >> > #include <asm-generic/qrwlock_types.h> >> > >> > #endif /* __ASM_CSKY_SPINLOCK_TYPES_H */
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