Source-Changes-D archive
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Old Index]
Re: CVS commit: src/sys [freeze on boot]
On Mon, 20 Jan 2020 at 13:06, Ryo ONODERA <ryo%tetera.org@localhost> wrote:
>
> Hi,
>
> Andrew Doran <ad%netbsd.org@localhost> writes:
>
> > Hi,
> >
> > This also happened the last time I touched rw_downgrade(), and I backed out
> > the change then, but both times I don't see the bug. I have some questions:
> >
> > - Are you running DIAGNOSTIC and/or LOCKDEBUG? I would be very interested
> > to see what happens with a LOCKDEBUG kernel here.
>
> I will enable LOCKDEBUG and DIAGNOSTIC soon.
>
> > - Do you have an ATI Radeon graphics chip?
> > - Are you using ZFS?
>
> My GPU is in Intel CPU (KabyLake Refresh).
> And I do not use ZFS at all. All partitions are FFSv2 with WAPBL.
If it may be of any help, the laptop I have which freezes upon
discovering the root device (dk1 in my case)
- has a Radeon graphics, which is disabled in boot.cfg (hardware fault
- if I do not disable it, the system gets reset immediately).
- I am using ZFS (two pools, one holding zvols for qemu-nvmm guess and
some iSCSI targets, the other a few zfs folders, especially the
CCACHE_DIR target gets used a lot)
- Also the root is on a GPT disk, EFI boot.
>
> > Thanks,
> > Andrew
> >
> >
> > On Mon, Jan 20, 2020 at 12:41:37PM +0900, Ryo ONODERA wrote:
> >> Hi,
> >>
> >> After this commit, the kernel stalls just before root file system
> >> will be found on my NetBSD/amd64 laptop.
> >>
> >> Reverting
> >> src/sys/kern/kern_rwlock.c to r1.60
> >> and
> >> src/sys/sys/rwlock.h to r1.12
> >> in latest -current tree and I can get the kernel that works like
> >> before.
> >>
> >> And on another laptop, the problematic kernel stalls before root file
> >> system detection like my laptop.
> >>
> >> It may be universal problem.
> >>
> >> Could you take a look at this problem?
> >>
> >> Thank you.
> >>
> >> "Andrew Doran" <ad%netbsd.org@localhost> writes:
> >>
> >> > Module Name: src
> >> > Committed By: ad
> >> > Date: Sun Jan 19 18:34:24 UTC 2020
> >> >
> >> > Modified Files:
> >> > src/sys/kern: kern_rwlock.c
> >> > src/sys/sys: rwlock.h
> >> >
> >> > Log Message:
> >> > Tidy rwlocks a bit, no functional change intended. Mainly:
> >> >
> >> > - rw_downgrade(): do it in a for () loop like all the others.
> >> > - Explicitly carry around RW_NODEBUG - don't be lazy.
> >> > - Remove pointless macros.
> >> > - Don't make assertions conditional on LOCKDEBUG, there's no reason.
> >> > - Make space for a new flag bit (not added yet).
> >> >
> >> >
> >> > To generate a diff of this commit:
> >> > cvs rdiff -u -r1.60 -r1.61 src/sys/kern/kern_rwlock.c
> >> > cvs rdiff -u -r1.12 -r1.13 src/sys/sys/rwlock.h
> >> >
> >> > Please note that diffs are not public domain; they are subject to the
> >> > copyright notices on the relevant files.
> >> >
> >> > Modified files:
> >> >
> >> > Index: src/sys/kern/kern_rwlock.c
> >> > diff -u src/sys/kern/kern_rwlock.c:1.60 src/sys/kern/kern_rwlock.c:1.61
> >> > --- src/sys/kern/kern_rwlock.c:1.60 Sun Jan 12 18:37:10 2020
> >> > +++ src/sys/kern/kern_rwlock.c Sun Jan 19 18:34:24 2020
> >> > @@ -1,4 +1,4 @@
> >> > -/* $NetBSD: kern_rwlock.c,v 1.60 2020/01/12 18:37:10 ad Exp $ */
> >> > +/* $NetBSD: kern_rwlock.c,v 1.61 2020/01/19 18:34:24 ad Exp $ */
> >> >
> >> > /*-
> >> > * Copyright (c) 2002, 2006, 2007, 2008, 2009, 2019, 2020
> >> > @@ -39,7 +39,9 @@
> >> > */
> >> >
> >> > #include <sys/cdefs.h>
> >> > -__KERNEL_RCSID(0, "$NetBSD: kern_rwlock.c,v 1.60 2020/01/12 18:37:10 ad Exp $");
> >> > +__KERNEL_RCSID(0, "$NetBSD: kern_rwlock.c,v 1.61 2020/01/19 18:34:24 ad Exp $");
> >> > +
> >> > +#include "opt_lockdebug.h"
> >> >
> >> > #define __RWLOCK_PRIVATE
> >> >
> >> > @@ -63,58 +65,32 @@ __KERNEL_RCSID(0, "$NetBSD: kern_rwlock.
> >> > * LOCKDEBUG
> >> > */
> >> >
> >> > -#if defined(LOCKDEBUG)
> >> > -
> >> > -#define RW_WANTLOCK(rw, op) \
> >> > - LOCKDEBUG_WANTLOCK(RW_DEBUG_P(rw), (rw), \
> >> > - (uintptr_t)__builtin_return_address(0), op == RW_READER);
> >> > -#define RW_LOCKED(rw, op) \
> >> > - LOCKDEBUG_LOCKED(RW_DEBUG_P(rw), (rw), NULL, \
> >> > - (uintptr_t)__builtin_return_address(0), op == RW_READER);
> >> > -#define RW_UNLOCKED(rw, op) \
> >> > - LOCKDEBUG_UNLOCKED(RW_DEBUG_P(rw), (rw), \
> >> > - (uintptr_t)__builtin_return_address(0), op == RW_READER);
> >> > -#define RW_DASSERT(rw, cond) \
> >> > -do { \
> >> > - if (__predict_false(!(cond))) \
> >> > - rw_abort(__func__, __LINE__, rw, "assertion failed: " #cond);\
> >> > -} while (/* CONSTCOND */ 0);
> >> > -
> >> > -#else /* LOCKDEBUG */
> >> > -
> >> > -#define RW_WANTLOCK(rw, op) /* nothing */
> >> > -#define RW_LOCKED(rw, op) /* nothing */
> >> > -#define RW_UNLOCKED(rw, op) /* nothing */
> >> > -#define RW_DASSERT(rw, cond) /* nothing */
> >> > +#define RW_DEBUG_P(rw) (((rw)->rw_owner & RW_NODEBUG) == 0)
> >> >
> >> > -#endif /* LOCKDEBUG */
> >> > +#define RW_WANTLOCK(rw, op) \
> >> > + LOCKDEBUG_WANTLOCK(RW_DEBUG_P(rw), (rw), \
> >> > + (uintptr_t)__builtin_return_address(0), op == RW_READER);
> >> > +#define RW_LOCKED(rw, op) \
> >> > + LOCKDEBUG_LOCKED(RW_DEBUG_P(rw), (rw), NULL, \
> >> > + (uintptr_t)__builtin_return_address(0), op == RW_READER);
> >> > +#define RW_UNLOCKED(rw, op) \
> >> > + LOCKDEBUG_UNLOCKED(RW_DEBUG_P(rw), (rw), \
> >> > + (uintptr_t)__builtin_return_address(0), op == RW_READER);
> >> >
> >> > /*
> >> > * DIAGNOSTIC
> >> > */
> >> >
> >> > #if defined(DIAGNOSTIC)
> >> > -
> >> > -#define RW_ASSERT(rw, cond) \
> >> > -do { \
> >> > - if (__predict_false(!(cond))) \
> >> > +#define RW_ASSERT(rw, cond) \
> >> > +do { \
> >> > + if (__predict_false(!(cond))) \
> >> > rw_abort(__func__, __LINE__, rw, "assertion failed: " #cond);\
> >> > } while (/* CONSTCOND */ 0)
> >> > -
> >> > #else
> >> > -
> >> > #define RW_ASSERT(rw, cond) /* nothing */
> >> > -
> >> > #endif /* DIAGNOSTIC */
> >> >
> >> > -#define RW_SETDEBUG(rw, on) ((rw)->rw_owner |= (on) ? 0 : RW_NODEBUG)
> >> > -#define RW_DEBUG_P(rw) (((rw)->rw_owner & RW_NODEBUG) == 0)
> >> > -#if defined(LOCKDEBUG)
> >> > -#define RW_INHERITDEBUG(n, o) (n) |= (o) & RW_NODEBUG
> >> > -#else /* defined(LOCKDEBUG) */
> >> > -#define RW_INHERITDEBUG(n, o) /* nothing */
> >> > -#endif /* defined(LOCKDEBUG) */
> >> > -
> >> > /*
> >> > * Memory barriers.
> >> > */
> >> > @@ -128,29 +104,6 @@ do { \
> >> > #define RW_MEMBAR_PRODUCER() membar_producer()
> >> > #endif
> >> >
> >> > -static void rw_abort(const char *, size_t, krwlock_t *, const char *);
> >> > -static void rw_dump(const volatile void *, lockop_printer_t);
> >> > -static lwp_t *rw_owner(wchan_t);
> >> > -
> >> > -static inline uintptr_t
> >> > -rw_cas(krwlock_t *rw, uintptr_t o, uintptr_t n)
> >> > -{
> >> > -
> >> > - RW_INHERITDEBUG(n, o);
> >> > - return (uintptr_t)atomic_cas_ptr((volatile void *)&rw->rw_owner,
> >> > - (void *)o, (void *)n);
> >> > -}
> >> > -
> >> > -static inline void
> >> > -rw_swap(krwlock_t *rw, uintptr_t o, uintptr_t n)
> >> > -{
> >> > -
> >> > - RW_INHERITDEBUG(n, o);
> >> > - n = (uintptr_t)atomic_swap_ptr((volatile void *)&rw->rw_owner,
> >> > - (void *)n);
> >> > - RW_DASSERT(rw, n == o);
> >> > -}
> >> > -
> >> > /*
> >> > * For platforms that do not provide stubs, or for the LOCKDEBUG case.
> >> > */
> >> > @@ -164,6 +117,10 @@ __strong_alias(rw_exit,rw_vector_exit);
> >> > __strong_alias(rw_tryenter,rw_vector_tryenter);
> >> > #endif
> >> >
> >> > +static void rw_abort(const char *, size_t, krwlock_t *, const char *);
> >> > +static void rw_dump(const volatile void *, lockop_printer_t);
> >> > +static lwp_t *rw_owner(wchan_t);
> >> > +
> >> > lockops_t rwlock_lockops = {
> >> > .lo_name = "Reader / writer lock",
> >> > .lo_type = LOCKOPS_SLEEP,
> >> > @@ -179,6 +136,37 @@ syncobj_t rw_syncobj = {
> >> > };
> >> >
> >> > /*
> >> > + * rw_cas:
> >> > + *
> >> > + * Do an atomic compare-and-swap on the lock word.
> >> > + */
> >> > +static inline uintptr_t
> >> > +rw_cas(krwlock_t *rw, uintptr_t o, uintptr_t n)
> >> > +{
> >> > +
> >> > + return (uintptr_t)atomic_cas_ptr((volatile void *)&rw->rw_owner,
> >> > + (void *)o, (void *)n);
> >> > +}
> >> > +
> >> > +/*
> >> > + * rw_swap:
> >> > + *
> >> > + * Do an atomic swap of the lock word. This is used only when it's
> >> > + * known that the lock word is set up such that it can't be changed
> >> > + * behind us (assert this), so there's no point considering the result.
> >> > + */
> >> > +static inline void
> >> > +rw_swap(krwlock_t *rw, uintptr_t o, uintptr_t n)
> >> > +{
> >> > +
> >> > + n = (uintptr_t)atomic_swap_ptr((volatile void *)&rw->rw_owner,
> >> > + (void *)n);
> >> > +
> >> > + RW_ASSERT(rw, n == o);
> >> > + RW_ASSERT(rw, (o & RW_HAS_WAITERS) != 0);
> >> > +}
> >> > +
> >> > +/*
> >> > * rw_dump:
> >> > *
> >> > * Dump the contents of a rwlock structure.
> >> > @@ -214,16 +202,14 @@ rw_abort(const char *func, size_t line,
> >> > *
> >> > * Initialize a rwlock for use.
> >> > */
> >> > -void _rw_init(krwlock_t *, uintptr_t);
> >> > void
> >> > _rw_init(krwlock_t *rw, uintptr_t return_address)
> >> > {
> >> > - bool dodebug;
> >> >
> >> > - memset(rw, 0, sizeof(*rw));
> >> > -
> >> > - dodebug = LOCKDEBUG_ALLOC(rw, &rwlock_lockops, return_address);
> >> > - RW_SETDEBUG(rw, dodebug);
> >> > + if (LOCKDEBUG_ALLOC(rw, &rwlock_lockops, return_address))
> >> > + rw->rw_owner = 0;
> >> > + else
> >> > + rw->rw_owner = RW_NODEBUG;
> >> > }
> >> >
> >> > void
> >> > @@ -243,7 +229,7 @@ rw_destroy(krwlock_t *rw)
> >> > {
> >> >
> >> > RW_ASSERT(rw, (rw->rw_owner & ~RW_NODEBUG) == 0);
> >> > - LOCKDEBUG_FREE(RW_DEBUG_P(rw), rw);
> >> > + LOCKDEBUG_FREE((rw->rw_owner & RW_NODEBUG) == 0, rw);
> >> > }
> >> >
> >> > /*
> >> > @@ -327,7 +313,7 @@ rw_vector_enter(krwlock_t *rw, const krw
> >> > need_wait = RW_WRITE_LOCKED | RW_WRITE_WANTED;
> >> > queue = TS_READER_Q;
> >> > } else {
> >> > - RW_DASSERT(rw, op == RW_WRITER);
> >> > + RW_ASSERT(rw, op == RW_WRITER);
> >> > incr = curthread | RW_WRITE_LOCKED;
> >> > set_wait = RW_HAS_WAITERS | RW_WRITE_WANTED;
> >> > need_wait = RW_WRITE_LOCKED | RW_THREAD;
> >> > @@ -430,7 +416,7 @@ rw_vector_enter(krwlock_t *rw, const krw
> >> > (uintptr_t)__builtin_return_address(0)));
> >> > LOCKSTAT_EXIT(lsflag);
> >> >
> >> > - RW_DASSERT(rw, (op != RW_READER && RW_OWNER(rw) == curthread) ||
> >> > + RW_ASSERT(rw, (op != RW_READER && RW_OWNER(rw) == curthread) ||
> >> > (op == RW_READER && RW_COUNT(rw) != 0));
> >> > RW_LOCKED(rw, op);
> >> > }
> >> > @@ -448,7 +434,8 @@ rw_vector_exit(krwlock_t *rw)
> >> > int rcnt, wcnt;
> >> > lwp_t *l;
> >> >
> >> > - curthread = (uintptr_t)curlwp;
> >> > + l = curlwp;
> >> > + curthread = (uintptr_t)l;
> >> > RW_ASSERT(rw, curthread != 0);
> >> >
> >> > /*
> >> > @@ -491,8 +478,8 @@ rw_vector_exit(krwlock_t *rw)
> >> > */
> >> > ts = turnstile_lookup(rw);
> >> > owner = rw->rw_owner;
> >> > - RW_DASSERT(rw, ts != NULL);
> >> > - RW_DASSERT(rw, (owner & RW_HAS_WAITERS) != 0);
> >> > + RW_ASSERT(rw, ts != NULL);
> >> > + RW_ASSERT(rw, (owner & RW_HAS_WAITERS) != 0);
> >> >
> >> > wcnt = TS_WAITERS(ts, TS_WRITER_Q);
> >> > rcnt = TS_WAITERS(ts, TS_READER_Q);
> >> > @@ -509,31 +496,35 @@ rw_vector_exit(krwlock_t *rw)
> >> > * do the work of acquiring the lock in rw_vector_enter().
> >> > */
> >> > if (rcnt == 0 || decr == RW_READ_INCR) {
> >> > - RW_DASSERT(rw, wcnt != 0);
> >> > - RW_DASSERT(rw, (owner & RW_WRITE_WANTED) != 0);
> >> > + RW_ASSERT(rw, wcnt != 0);
> >> > + RW_ASSERT(rw, (owner & RW_WRITE_WANTED) != 0);
> >> >
> >> > if (rcnt != 0) {
> >> > /* Give the lock to the longest waiting writer. */
> >> > l = TS_FIRST(ts, TS_WRITER_Q);
> >> > - newown = (uintptr_t)l | RW_WRITE_LOCKED | RW_HAS_WAITERS;
> >> > + newown = (uintptr_t)l | (owner & RW_NODEBUG);
> >> > + newown |= RW_WRITE_LOCKED | RW_HAS_WAITERS;
> >> > if (wcnt > 1)
> >> > newown |= RW_WRITE_WANTED;
> >> > rw_swap(rw, owner, newown);
> >> > turnstile_wakeup(ts, TS_WRITER_Q, 1, l);
> >> > } else {
> >> > /* Wake all writers and let them fight it out. */
> >> > - rw_swap(rw, owner, RW_WRITE_WANTED);
> >> > + newown = owner & RW_NODEBUG;
> >> > + newown |= RW_WRITE_WANTED;
> >> > + rw_swap(rw, owner, newown);
> >> > turnstile_wakeup(ts, TS_WRITER_Q, wcnt, NULL);
> >> > }
> >> > } else {
> >> > - RW_DASSERT(rw, rcnt != 0);
> >> > + RW_ASSERT(rw, rcnt != 0);
> >> >
> >> > /*
> >> > * Give the lock to all blocked readers. If there
> >> > * is a writer waiting, new readers that arrive
> >> > * after the release will be blocked out.
> >> > */
> >> > - newown = rcnt << RW_READ_COUNT_SHIFT;
> >> > + newown = owner & RW_NODEBUG;
> >> > + newown += rcnt << RW_READ_COUNT_SHIFT;
> >> > if (wcnt != 0)
> >> > newown |= RW_HAS_WAITERS | RW_WRITE_WANTED;
> >> >
> >> > @@ -552,8 +543,10 @@ int
> >> > rw_vector_tryenter(krwlock_t *rw, const krw_t op)
> >> > {
> >> > uintptr_t curthread, owner, incr, need_wait, next;
> >> > + lwp_t *l;
> >> >
> >> > - curthread = (uintptr_t)curlwp;
> >> > + l = curlwp;
> >> > + curthread = (uintptr_t)l;
> >> >
> >> > RW_ASSERT(rw, curthread != 0);
> >> >
> >> > @@ -561,7 +554,7 @@ rw_vector_tryenter(krwlock_t *rw, const
> >> > incr = RW_READ_INCR;
> >> > need_wait = RW_WRITE_LOCKED | RW_WRITE_WANTED;
> >> > } else {
> >> > - RW_DASSERT(rw, op == RW_WRITER);
> >> > + RW_ASSERT(rw, op == RW_WRITER);
> >> > incr = curthread | RW_WRITE_LOCKED;
> >> > need_wait = RW_WRITE_LOCKED | RW_THREAD;
> >> > }
> >> > @@ -572,24 +565,23 @@ rw_vector_tryenter(krwlock_t *rw, const
> >> > next = rw_cas(rw, owner, owner + incr);
> >> > if (__predict_true(next == owner)) {
> >> > /* Got it! */
> >> > - RW_MEMBAR_ENTER();
> >> > break;
> >> > }
> >> > }
> >> >
> >> > RW_WANTLOCK(rw, op);
> >> > RW_LOCKED(rw, op);
> >> > - RW_DASSERT(rw, (op != RW_READER && RW_OWNER(rw) == curthread) ||
> >> > + RW_ASSERT(rw, (op != RW_READER && RW_OWNER(rw) == curthread) ||
> >> > (op == RW_READER && RW_COUNT(rw) != 0));
> >> >
> >> > + RW_MEMBAR_ENTER();
> >> > return 1;
> >> > }
> >> >
> >> > /*
> >> > * rw_downgrade:
> >> > *
> >> > - * Downgrade a write lock to a read lock. Optimise memory accesses for
> >> > - * the uncontended case.
> >> > + * Downgrade a write lock to a read lock.
> >> > */
> >> > void
> >> > rw_downgrade(krwlock_t *rw)
> >> > @@ -597,55 +589,64 @@ rw_downgrade(krwlock_t *rw)
> >> > uintptr_t owner, curthread, newown, next;
> >> > turnstile_t *ts;
> >> > int rcnt, wcnt;
> >> > + lwp_t *l;
> >> >
> >> > - curthread = (uintptr_t)curlwp;
> >> > + l = curlwp;
> >> > + curthread = (uintptr_t)l;
> >> > RW_ASSERT(rw, curthread != 0);
> >> > - RW_DASSERT(rw, (rw->rw_owner & RW_WRITE_LOCKED) != 0);
> >> > + RW_ASSERT(rw, (rw->rw_owner & RW_WRITE_LOCKED) != 0);
> >> > RW_ASSERT(rw, RW_OWNER(rw) == curthread);
> >> > RW_UNLOCKED(rw, RW_WRITER);
> >> > #if !defined(DIAGNOSTIC)
> >> > __USE(curthread);
> >> > #endif
> >> >
> >> > - /*
> >> > - * If there are no waiters, so we can do this the easy way.
> >> > - * Try swapping us down to one read hold. If it fails, the
> >> > - * lock condition has changed and we most likely now have
> >> > - * waiters.
> >> > - */
> >> > RW_MEMBAR_PRODUCER();
> >> > - owner = curthread | RW_WRITE_LOCKED;
> >> > - next = rw_cas(rw, owner, RW_READ_INCR);
> >> > - if (__predict_true(next == owner)) {
> >> > - RW_LOCKED(rw, RW_READER);
> >> > - RW_DASSERT(rw, (rw->rw_owner & RW_WRITE_LOCKED) == 0);
> >> > - RW_DASSERT(rw, RW_COUNT(rw) != 0);
> >> > - return;
> >> > - }
> >> >
> >> > - /*
> >> > - * Grab the turnstile chain lock. This gets the interlock
> >> > - * on the sleep queue. Once we have that, we can adjust the
> >> > - * waiter bits.
> >> > - */
> >> > - for (;;) {
> >> > - owner = next;
> >> > + for (owner = rw->rw_owner;; owner = next) {
> >> > + /*
> >> > + * If there are no waiters we can do this the easy way. Try
> >> > + * swapping us down to one read hold. If it fails, the lock
> >> > + * condition has changed and we most likely now have
> >> > + * waiters.
> >> > + */
> >> > + if ((owner & RW_HAS_WAITERS) == 0) {
> >> > + newown = (owner & RW_NODEBUG);
> >> > + next = rw_cas(rw, owner, newown + RW_READ_INCR);
> >> > + if (__predict_true(next == owner)) {
> >> > + RW_LOCKED(rw, RW_READER);
> >> > + RW_ASSERT(rw,
> >> > + (rw->rw_owner & RW_WRITE_LOCKED) == 0);
> >> > + RW_ASSERT(rw, RW_COUNT(rw) != 0);
> >> > + return;
> >> > + }
> >> > + continue;
> >> > + }
> >> > +
> >> > + /*
> >> > + * Grab the turnstile chain lock. This gets the interlock
> >> > + * on the sleep queue. Once we have that, we can adjust the
> >> > + * waiter bits.
> >> > + */
> >> > ts = turnstile_lookup(rw);
> >> > - RW_DASSERT(rw, ts != NULL);
> >> > + RW_ASSERT(rw, ts != NULL);
> >> >
> >> > rcnt = TS_WAITERS(ts, TS_READER_Q);
> >> > wcnt = TS_WAITERS(ts, TS_WRITER_Q);
> >> >
> >> > - /*
> >> > - * If there are no readers, just preserve the waiters
> >> > - * bits, swap us down to one read hold and return.
> >> > - */
> >> > if (rcnt == 0) {
> >> > - RW_DASSERT(rw, wcnt != 0);
> >> > - RW_DASSERT(rw, (rw->rw_owner & RW_WRITE_WANTED) != 0);
> >> > - RW_DASSERT(rw, (rw->rw_owner & RW_HAS_WAITERS) != 0);
> >> > -
> >> > - newown = RW_READ_INCR | RW_HAS_WAITERS | RW_WRITE_WANTED;
> >> > + /*
> >> > + * If there are no readers, just preserve the
> >> > + * waiters bits, swap us down to one read hold and
> >> > + * return.
> >> > + */
> >> > + RW_ASSERT(rw, wcnt != 0);
> >> > + RW_ASSERT(rw, (rw->rw_owner & RW_WRITE_WANTED) != 0);
> >> > + RW_ASSERT(rw, (rw->rw_owner & RW_HAS_WAITERS) != 0);
> >> > +
> >> > + newown = owner & RW_NODEBUG;
> >> > + newown = RW_READ_INCR | RW_HAS_WAITERS |
> >> > + RW_WRITE_WANTED;
> >> > next = rw_cas(rw, owner, newown);
> >> > turnstile_exit(rw);
> >> > if (__predict_true(next == owner))
> >> > @@ -653,11 +654,12 @@ rw_downgrade(krwlock_t *rw)
> >> > } else {
> >> > /*
> >> > * Give the lock to all blocked readers. We may
> >> > - * retain one read hold if downgrading. If there
> >> > - * is a writer waiting, new readers will be blocked
> >> > + * retain one read hold if downgrading. If there is
> >> > + * a writer waiting, new readers will be blocked
> >> > * out.
> >> > */
> >> > - newown = (rcnt << RW_READ_COUNT_SHIFT) + RW_READ_INCR;
> >> > + newown = owner & RW_NODEBUG;
> >> > + newown += (rcnt << RW_READ_COUNT_SHIFT) + RW_READ_INCR;
> >> > if (wcnt != 0)
> >> > newown |= RW_HAS_WAITERS | RW_WRITE_WANTED;
> >> >
> >> > @@ -673,22 +675,24 @@ rw_downgrade(krwlock_t *rw)
> >> >
> >> > RW_WANTLOCK(rw, RW_READER);
> >> > RW_LOCKED(rw, RW_READER);
> >> > - RW_DASSERT(rw, (rw->rw_owner & RW_WRITE_LOCKED) == 0);
> >> > - RW_DASSERT(rw, RW_COUNT(rw) != 0);
> >> > + RW_ASSERT(rw, (rw->rw_owner & RW_WRITE_LOCKED) == 0);
> >> > + RW_ASSERT(rw, RW_COUNT(rw) != 0);
> >> > }
> >> >
> >> > /*
> >> > * rw_tryupgrade:
> >> > *
> >> > * Try to upgrade a read lock to a write lock. We must be the only
> >> > - * reader. Optimise memory accesses for the uncontended case.
> >> > + * reader.
> >> > */
> >> > int
> >> > rw_tryupgrade(krwlock_t *rw)
> >> > {
> >> > uintptr_t owner, curthread, newown, next;
> >> > + struct lwp *l;
> >> >
> >> > - curthread = (uintptr_t)curlwp;
> >> > + l = curlwp;
> >> > + curthread = (uintptr_t)l;
> >> > RW_ASSERT(rw, curthread != 0);
> >> > RW_ASSERT(rw, rw_read_held(rw));
> >> >
> >> > @@ -709,8 +713,8 @@ rw_tryupgrade(krwlock_t *rw)
> >> > RW_UNLOCKED(rw, RW_READER);
> >> > RW_WANTLOCK(rw, RW_WRITER);
> >> > RW_LOCKED(rw, RW_WRITER);
> >> > - RW_DASSERT(rw, rw->rw_owner & RW_WRITE_LOCKED);
> >> > - RW_DASSERT(rw, RW_OWNER(rw) == curthread);
> >> > + RW_ASSERT(rw, rw->rw_owner & RW_WRITE_LOCKED);
> >> > + RW_ASSERT(rw, RW_OWNER(rw) == curthread);
> >> >
> >> > return 1;
> >> > }
> >> >
> >> > Index: src/sys/sys/rwlock.h
> >> > diff -u src/sys/sys/rwlock.h:1.12 src/sys/sys/rwlock.h:1.13
> >> > --- src/sys/sys/rwlock.h:1.12 Wed Jan 1 21:34:39 2020
> >> > +++ src/sys/sys/rwlock.h Sun Jan 19 18:34:24 2020
> >> > @@ -1,7 +1,7 @@
> >> > -/* $NetBSD: rwlock.h,v 1.12 2020/01/01 21:34:39 ad Exp $ */
> >> > +/* $NetBSD: rwlock.h,v 1.13 2020/01/19 18:34:24 ad Exp $ */
> >> >
> >> > /*-
> >> > - * Copyright (c) 2002, 2006, 2007, 2008, 2019 The NetBSD Foundation, Inc.
> >> > + * Copyright (c) 2002, 2006, 2007, 2008, 2019, 2020 The NetBSD Foundation, Inc.
> >> > * All rights reserved.
> >> > *
> >> > * This code is derived from software contributed to The NetBSD Foundation
> >> > @@ -45,10 +45,6 @@
> >> > * rw_tryenter()
> >> > */
> >> >
> >> > -#if defined(_KERNEL_OPT)
> >> > -#include "opt_lockdebug.h"
> >> > -#endif
> >> > -
> >> > #if !defined(_KERNEL)
> >> > #include <sys/types.h>
> >> > #include <sys/inttypes.h>
> >> > @@ -75,13 +71,9 @@ typedef struct krwlock krwlock_t;
> >> > #define RW_HAS_WAITERS 0x01UL /* lock has waiters */
> >> > #define RW_WRITE_WANTED 0x02UL /* >= 1 waiter is a writer */
> >> > #define RW_WRITE_LOCKED 0x04UL /* lock is currently write locked */
> >> > -#if defined(LOCKDEBUG)
> >> > -#define RW_NODEBUG 0x08UL /* LOCKDEBUG disabled */
> >> > -#else
> >> > -#define RW_NODEBUG 0x00UL /* do nothing */
> >> > -#endif /* LOCKDEBUG */
> >> > +#define RW_NODEBUG 0x10UL /* LOCKDEBUG disabled */
> >> >
> >> > -#define RW_READ_COUNT_SHIFT 4
> >> > +#define RW_READ_COUNT_SHIFT 5
> >> > #define RW_READ_INCR (1UL << RW_READ_COUNT_SHIFT)
> >> > #define RW_THREAD ((uintptr_t)-RW_READ_INCR)
> >> > #define RW_OWNER(rw) ((rw)->rw_owner & RW_THREAD)
> >> > @@ -91,6 +83,7 @@ typedef struct krwlock krwlock_t;
> >> > void rw_vector_enter(krwlock_t *, const krw_t);
> >> > void rw_vector_exit(krwlock_t *);
> >> > int rw_vector_tryenter(krwlock_t *, const krw_t);
> >> > +void _rw_init(krwlock_t *, uintptr_t);
> >> > #endif /* __RWLOCK_PRIVATE */
> >> >
> >> > struct krwlock {
> >> >
> >>
> >> --
> >> Ryo ONODERA // ryo%tetera.org@localhost
> >> PGP fingerprint = 82A2 DC91 76E0 A10A 8ABB FD1B F404 27FA C7D1 15F3
>
> --
> Ryo ONODERA // ryo%tetera.org@localhost
> PGP fingerprint = 82A2 DC91 76E0 A10A 8ABB FD1B F404 27FA C7D1 15F3
--
----
Home |
Main Index |
Thread Index |
Old Index