From 3a5fa7ed9020eaf8ab843a16d26db7393b2ec072 Mon Sep 17 00:00:00 2001 From: Frans Kaashoek Date: Fri, 26 Aug 2011 10:08:29 -0400 Subject: Introduce and use sleeplocks instead of BUSY flags Remove I_BUSY, B_BUSY, and intrans defs and usages One spinlock per buf to avoid ugly loop in bget fix race in filewrite (don't update f->off after releasing lock) --- spinlock.c | 42 ++++++++++++++++++++++++++++++++++++++---- 1 file changed, 38 insertions(+), 4 deletions(-) (limited to 'spinlock.c') diff --git a/spinlock.c b/spinlock.c index a16621c..c1f6a96 100644 --- a/spinlock.c +++ b/spinlock.c @@ -17,10 +17,9 @@ initlock(struct spinlock *lk, char *name) lk->cpu = 0; } -// Acquire the lock. -// Loops (spins) until the lock is acquired. -// Holding a lock for a long time may cause -// other CPUs to waste time spinning to acquire it. +// Acquire a spin lock. Loops (spins) until the lock is acquired. +// Holding a lock for a long time may cause other CPUs to waste time spinning to acquire it. +// Spinlocks shouldn't be held across sleep(); for those cases, use sleeplocks. void acquire(struct spinlock *lk) { @@ -115,3 +114,38 @@ popcli(void) sti(); } +void +initsleeplock(struct sleeplock *l) +{ + l->locked = 0; +} + +// Grab the sleeplock that is protected by spinl. Sleeplocks allow a process to lock +// a data structure for long times, including across sleeps. Other processes that try +// to acquire a sleeplock will be put to sleep when another process hold the sleeplock. +// To update status of the sleeplock atomically, the caller must hold spinl +void +acquire_sleeplock(struct sleeplock *sleepl, struct spinlock *spinl) +{ + while (sleepl->locked) { + sleep(sleepl, spinl); + } + sleepl->locked = 1; +} + +// Release the sleeplock that is protected by a spin lock +// Caller must hold the spinlock that protects the sleeplock +void +release_sleeplock(struct sleeplock *sleepl) +{ + sleepl->locked = 0; + wakeup(sleepl); +} + +// Is the sleeplock acquired? +// Caller must hold the spinlock that protects the sleeplock +int +acquired_sleeplock(struct sleeplock *sleepl) +{ + return sleepl->locked; +} -- cgit v1.2.3