witness: sleepable rm locks are not sleepable in read mode
There are two classes of rm lock, one "sleepable" and one not. But even a "sleepable" rm lock is only sleepable in write mode, and is non-sleepable when taken in read mode. Warn about sleepable rm locks in read mode as non-sleepable locks. Do this by defining a new lock operation flag, LOP_NOSLEEP, to indicate that a lock is non-sleepable despite what the LO_SLEEPABLE flag would indicate, and defining a new witness lock instance flag, LI_SLEEPABLE, to track the product of LO_SLEEPABLE and LOP_NOSLEEP on the lock instance. Reviewed by: markj Sponsored by: Dell EMC Isilon Differential Revision: https://reviews.freebsd.org/D22527
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Notes:
svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=355126
@ -652,8 +652,8 @@ _rm_rlock_debug(struct rmlock *rm, struct rm_priotracker *tracker,
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KASSERT(!rm_wowned(rm),
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("rm_rlock: wlock already held for %s @ %s:%d",
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rm->lock_object.lo_name, file, line));
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WITNESS_CHECKORDER(&rm->lock_object, LOP_NEWORDER, file, line,
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NULL);
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WITNESS_CHECKORDER(&rm->lock_object,
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LOP_NEWORDER | LOP_NOSLEEP, file, line, NULL);
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}
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if (_rm_rlock(rm, tracker, trylock)) {
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@ -663,7 +663,7 @@ _rm_rlock_debug(struct rmlock *rm, struct rm_priotracker *tracker,
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else
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LOCK_LOG_LOCK("RMRLOCK", &rm->lock_object, 0, 0, file,
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line);
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WITNESS_LOCK(&rm->lock_object, 0, file, line);
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WITNESS_LOCK(&rm->lock_object, LOP_NOSLEEP, file, line);
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TD_LOCKS_INC(curthread);
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return (1);
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} else if (trylock)
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@ -131,6 +131,7 @@ __FBSDID("$FreeBSD$");
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#define LI_RECURSEMASK 0x0000ffff /* Recursion depth of lock instance. */
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#define LI_EXCLUSIVE 0x00010000 /* Exclusive lock instance. */
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#define LI_NORELEASE 0x00020000 /* Lock not allowed to be released. */
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#define LI_SLEEPABLE 0x00040000 /* Lock may be held while sleeping. */
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#ifndef WITNESS_COUNT
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#define WITNESS_COUNT 1536
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@ -1302,7 +1303,7 @@ witness_checkorder(struct lock_object *lock, int flags, const char *file,
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* If we are locking Giant and this is a sleepable
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* lock, then skip it.
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*/
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if ((lock1->li_lock->lo_flags & LO_SLEEPABLE) != 0 &&
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if ((lock1->li_flags & LI_SLEEPABLE) != 0 &&
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lock == &Giant.lock_object)
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continue;
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@ -1311,6 +1312,7 @@ witness_checkorder(struct lock_object *lock, int flags, const char *file,
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* is Giant, then skip it.
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*/
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if ((lock->lo_flags & LO_SLEEPABLE) != 0 &&
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(flags & LOP_NOSLEEP) == 0 &&
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lock1->li_lock == &Giant.lock_object)
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continue;
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@ -1320,15 +1322,16 @@ witness_checkorder(struct lock_object *lock, int flags, const char *file,
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* order violation to enfore a general lock order of
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* sleepable locks before non-sleepable locks.
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*/
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if (((lock->lo_flags & LO_SLEEPABLE) != 0 &&
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(lock1->li_lock->lo_flags & LO_SLEEPABLE) == 0))
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if ((lock->lo_flags & LO_SLEEPABLE) != 0 &&
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(flags & LOP_NOSLEEP) == 0 &&
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(lock1->li_flags & LI_SLEEPABLE) == 0)
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goto reversal;
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/*
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* If we are locking Giant and this is a non-sleepable
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* lock, then treat it as a reversal.
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*/
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if ((lock1->li_lock->lo_flags & LO_SLEEPABLE) == 0 &&
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if ((lock1->li_flags & LI_SLEEPABLE) == 0 &&
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lock == &Giant.lock_object)
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goto reversal;
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@ -1378,11 +1381,12 @@ witness_checkorder(struct lock_object *lock, int flags, const char *file,
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/*
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* Ok, yell about it.
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*/
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if (((lock->lo_flags & LO_SLEEPABLE) != 0 &&
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(lock1->li_lock->lo_flags & LO_SLEEPABLE) == 0))
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if ((lock->lo_flags & LO_SLEEPABLE) != 0 &&
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(flags & LOP_NOSLEEP) == 0 &&
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(lock1->li_flags & LI_SLEEPABLE) == 0)
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witness_output(
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"lock order reversal: (sleepable after non-sleepable)\n");
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else if ((lock1->li_lock->lo_flags & LO_SLEEPABLE) == 0
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else if ((lock1->li_flags & LI_SLEEPABLE) == 0
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&& lock == &Giant.lock_object)
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witness_output(
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"lock order reversal: (Giant after non-sleepable)\n");
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@ -1440,7 +1444,8 @@ witness_checkorder(struct lock_object *lock, int flags, const char *file,
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*/
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if (flags & LOP_NEWORDER &&
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!(plock->li_lock == &Giant.lock_object &&
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(lock->lo_flags & LO_SLEEPABLE) != 0)) {
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(lock->lo_flags & LO_SLEEPABLE) != 0 &&
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(flags & LOP_NOSLEEP) == 0)) {
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CTR3(KTR_WITNESS, "%s: adding %s as a child of %s", __func__,
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w->w_name, plock->li_lock->lo_witness->w_name);
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itismychild(plock->li_lock->lo_witness, w);
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@ -1500,10 +1505,11 @@ witness_lock(struct lock_object *lock, int flags, const char *file, int line)
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instance->li_lock = lock;
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instance->li_line = line;
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instance->li_file = file;
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instance->li_flags = 0;
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if ((flags & LOP_EXCLUSIVE) != 0)
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instance->li_flags = LI_EXCLUSIVE;
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else
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instance->li_flags = 0;
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instance->li_flags |= LI_EXCLUSIVE;
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if ((lock->lo_flags & LO_SLEEPABLE) != 0 && (flags & LOP_NOSLEEP) == 0)
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instance->li_flags |= LI_SLEEPABLE;
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CTR4(KTR_WITNESS, "%s: pid %d added %s as lle[%d]", __func__,
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td->td_proc->p_pid, lock->lo_name, lle->ll_count - 1);
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}
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@ -1763,7 +1769,7 @@ witness_warn(int flags, struct lock_object *lock, const char *fmt, ...)
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lock1->li_lock == &Giant.lock_object)
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continue;
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if (flags & WARN_SLEEPOK &&
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(lock1->li_lock->lo_flags & LO_SLEEPABLE) != 0)
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(lock1->li_flags & LI_SLEEPABLE) != 0)
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continue;
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if (n == 0) {
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va_start(ap, fmt);
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@ -107,6 +107,7 @@ struct lock_class {
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#define LOP_TRYLOCK 0x00000004 /* Don't check lock order. */
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#define LOP_EXCLUSIVE 0x00000008 /* Exclusive lock. */
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#define LOP_DUPOK 0x00000010 /* Don't check for duplicate acquires */
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#define LOP_NOSLEEP 0x00000020 /* Non-sleepable despite LO_SLEEPABLE */
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/* Flags passed to witness_assert. */
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#define LA_MASKASSERT 0x000000ff /* Mask for witness defined asserts. */
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