Date: Sat, 6 Mar 2021 02:07:04 GMT From: Konstantin Belousov <kib@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-branches@FreeBSD.org Subject: git: c10e0a4656bf - stable/13 - Use atomic_interrupt_fence() instead of bare __compiler_membar() Message-ID: <202103060207.126274uN021364@gitrepo.freebsd.org>
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The branch stable/13 has been updated by kib: URL: https://cgit.FreeBSD.org/src/commit/?id=c10e0a4656bfe650bb3bf46fcf026a8a51a34a69 commit c10e0a4656bfe650bb3bf46fcf026a8a51a34a69 Author: Konstantin Belousov <kib@FreeBSD.org> AuthorDate: 2021-02-26 23:54:17 +0000 Commit: Konstantin Belousov <kib@FreeBSD.org> CommitDate: 2021-03-06 02:06:55 +0000 Use atomic_interrupt_fence() instead of bare __compiler_membar() (cherry picked from commit b5449c92b489445635c7962875ce73b2c9211bba) --- sys/kern/kern_rmlock.c | 32 +++++++++++++++----------------- sys/sys/kpilite.h | 5 ++--- sys/sys/mount.h | 4 ++-- sys/sys/sched.h | 4 ++-- sys/sys/systm.h | 6 +++--- 5 files changed, 24 insertions(+), 27 deletions(-) diff --git a/sys/kern/kern_rmlock.c b/sys/kern/kern_rmlock.c index 9135709d88cf..f661e209b633 100644 --- a/sys/kern/kern_rmlock.c +++ b/sys/kern/kern_rmlock.c @@ -366,7 +366,7 @@ _rm_rlock_hard(struct rmlock *rm, struct rm_priotracker *tracker, int trylock) * Check to see if the IPI granted us the lock after all. The load of * rmp_flags must happen after the tracker is removed from the list. */ - __compiler_membar(); + atomic_interrupt_fence(); if (tracker->rmp_flags) { /* Just add back tracker - we hold the lock. */ rm_tracker_add(pc, tracker); @@ -448,7 +448,7 @@ _rm_rlock(struct rmlock *rm, struct rm_priotracker *tracker, int trylock) td->td_critnest++; /* critical_enter(); */ - __compiler_membar(); + atomic_interrupt_fence(); pc = cpuid_to_pcpu[td->td_oncpu]; /* pcpu_find(td->td_oncpu); */ @@ -456,7 +456,7 @@ _rm_rlock(struct rmlock *rm, struct rm_priotracker *tracker, int trylock) sched_pin(); - __compiler_membar(); + atomic_interrupt_fence(); td->td_critnest--; @@ -873,17 +873,15 @@ db_show_rm(const struct lock_object *lock) * Concurrent writers take turns taking the lock while going off cpu. If this is * of concern for your usecase, this is not the right primitive. * - * Neither rms_rlock nor rms_runlock use fences. Instead compiler barriers are - * inserted to prevert reordering of generated code. Execution ordering is - * provided with the use of an IPI handler. + * Neither rms_rlock nor rms_runlock use thread fences. Instead interrupt + * fences are inserted to ensure ordering with the code executed in the IPI + * handler. * * No attempt is made to track which CPUs read locked at least once, * consequently write locking sends IPIs to all of them. This will become a * problem at some point. The easiest way to lessen it is to provide a bitmap. */ -#define rms_int_membar() __compiler_membar() - #define RMS_NOOWNER ((void *)0x1) #define RMS_TRANSIENT ((void *)0x2) #define RMS_FLAGMASK 0xf @@ -1030,14 +1028,14 @@ rms_rlock(struct rmslock *rms) critical_enter(); pcpu = rms_int_pcpu(rms); rms_int_influx_enter(rms, pcpu); - rms_int_membar(); + atomic_interrupt_fence(); if (__predict_false(rms->writers > 0)) { rms_rlock_fallback(rms); return; } - rms_int_membar(); + atomic_interrupt_fence(); rms_int_readers_inc(rms, pcpu); - rms_int_membar(); + atomic_interrupt_fence(); rms_int_influx_exit(rms, pcpu); critical_exit(); } @@ -1052,15 +1050,15 @@ rms_try_rlock(struct rmslock *rms) critical_enter(); pcpu = rms_int_pcpu(rms); rms_int_influx_enter(rms, pcpu); - rms_int_membar(); + atomic_interrupt_fence(); if (__predict_false(rms->writers > 0)) { rms_int_influx_exit(rms, pcpu); critical_exit(); return (0); } - rms_int_membar(); + atomic_interrupt_fence(); rms_int_readers_inc(rms, pcpu); - rms_int_membar(); + atomic_interrupt_fence(); rms_int_influx_exit(rms, pcpu); critical_exit(); return (1); @@ -1092,14 +1090,14 @@ rms_runlock(struct rmslock *rms) critical_enter(); pcpu = rms_int_pcpu(rms); rms_int_influx_enter(rms, pcpu); - rms_int_membar(); + atomic_interrupt_fence(); if (__predict_false(rms->writers > 0)) { rms_runlock_fallback(rms); return; } - rms_int_membar(); + atomic_interrupt_fence(); rms_int_readers_dec(rms, pcpu); - rms_int_membar(); + atomic_interrupt_fence(); rms_int_influx_exit(rms, pcpu); critical_exit(); } diff --git a/sys/sys/kpilite.h b/sys/sys/kpilite.h index 8742ef5cfbe8..2a7e9743f799 100644 --- a/sys/sys/kpilite.h +++ b/sys/sys/kpilite.h @@ -38,7 +38,7 @@ sched_pin_lite(struct thread_lite *td) KASSERT((struct thread *)td == curthread, ("sched_pin called on non curthread")); td->td_pinned++; - __compiler_membar(); + atomic_interrupt_fence(); } static __inline void @@ -47,9 +47,8 @@ sched_unpin_lite(struct thread_lite *td) KASSERT((struct thread *)td == curthread, ("sched_unpin called on non curthread")); KASSERT(td->td_pinned > 0, ("sched_unpin called on non pinned thread")); - __compiler_membar(); + atomic_interrupt_fence(); td->td_pinned--; - __compiler_membar(); } #endif #endif diff --git a/sys/sys/mount.h b/sys/sys/mount.h index f965dd72d7ba..98d50161bed5 100644 --- a/sys/sys/mount.h +++ b/sys/sys/mount.h @@ -1086,7 +1086,7 @@ void resume_all_fs(void); _mpcpu = vfs_mount_pcpu(mp); \ MPASS(mpcpu->mntp_thread_in_ops == 0); \ _mpcpu->mntp_thread_in_ops = 1; \ - __compiler_membar(); \ + atomic_interrupt_fence(); \ if (__predict_false(mp->mnt_vfs_ops > 0)) { \ vfs_op_thread_exit_crit(mp, _mpcpu); \ _retval_crit = false; \ @@ -1106,7 +1106,7 @@ void resume_all_fs(void); #define vfs_op_thread_exit_crit(mp, _mpcpu) do { \ MPASS(_mpcpu == vfs_mount_pcpu(mp)); \ MPASS(_mpcpu->mntp_thread_in_ops == 1); \ - __compiler_membar(); \ + atomic_interrupt_fence(); \ _mpcpu->mntp_thread_in_ops = 0; \ } while (0) diff --git a/sys/sys/sched.h b/sys/sys/sched.h index d734ec61266e..64651ffa9c90 100644 --- a/sys/sys/sched.h +++ b/sys/sys/sched.h @@ -173,13 +173,13 @@ static __inline void sched_pin(void) { curthread->td_pinned++; - __compiler_membar(); + atomic_interrupt_fence(); } static __inline void sched_unpin(void) { - __compiler_membar(); + atomic_interrupt_fence(); curthread->td_pinned--; } diff --git a/sys/sys/systm.h b/sys/sys/systm.h index 5de12e5bc1e5..72a10c401af9 100644 --- a/sys/sys/systm.h +++ b/sys/sys/systm.h @@ -284,7 +284,7 @@ critical_enter(void) td = (struct thread_lite *)curthread; td->td_critnest++; - __compiler_membar(); + atomic_interrupt_fence(); } static __inline void @@ -295,9 +295,9 @@ critical_exit(void) td = (struct thread_lite *)curthread; KASSERT(td->td_critnest != 0, ("critical_exit: td_critnest == 0")); - __compiler_membar(); + atomic_interrupt_fence(); td->td_critnest--; - __compiler_membar(); + atomic_interrupt_fence(); if (__predict_false(td->td_owepreempt)) critical_exit_preempt();
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