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![Ingo Molnar](/assets/img/avatar_default.png)
This patch (written by me and also containing many suggestions of Arjan van de Ven) does a major cleanup of the spinlock code. It does the following things: - consolidates and enhances the spinlock/rwlock debugging code - simplifies the asm/spinlock.h files - encapsulates the raw spinlock type and moves generic spinlock features (such as ->break_lock) into the generic code. - cleans up the spinlock code hierarchy to get rid of the spaghetti. Most notably there's now only a single variant of the debugging code, located in lib/spinlock_debug.c. (previously we had one SMP debugging variant per architecture, plus a separate generic one for UP builds) Also, i've enhanced the rwlock debugging facility, it will now track write-owners. There is new spinlock-owner/CPU-tracking on SMP builds too. All locks have lockup detection now, which will work for both soft and hard spin/rwlock lockups. The arch-level include files now only contain the minimally necessary subset of the spinlock code - all the rest that can be generalized now lives in the generic headers: include/asm-i386/spinlock_types.h | 16 include/asm-x86_64/spinlock_types.h | 16 I have also split up the various spinlock variants into separate files, making it easier to see which does what. The new layout is: SMP | UP ----------------------------|----------------------------------- asm/spinlock_types_smp.h | linux/spinlock_types_up.h linux/spinlock_types.h | linux/spinlock_types.h asm/spinlock_smp.h | linux/spinlock_up.h linux/spinlock_api_smp.h | linux/spinlock_api_up.h linux/spinlock.h | linux/spinlock.h /* * here's the role of the various spinlock/rwlock related include files: * * on SMP builds: * * asm/spinlock_types.h: contains the raw_spinlock_t/raw_rwlock_t and the * initializers * * linux/spinlock_types.h: * defines the generic type and initializers * * asm/spinlock.h: contains the __raw_spin_*()/etc. lowlevel * implementations, mostly inline assembly code * * (also included on UP-debug builds:) * * linux/spinlock_api_smp.h: * contains the prototypes for the _spin_*() APIs. * * linux/spinlock.h: builds the final spin_*() APIs. * * on UP builds: * * linux/spinlock_type_up.h: * contains the generic, simplified UP spinlock type. * (which is an empty structure on non-debug builds) * * linux/spinlock_types.h: * defines the generic type and initializers * * linux/spinlock_up.h: * contains the __raw_spin_*()/etc. version of UP * builds. (which are NOPs on non-debug, non-preempt * builds) * * (included on UP-non-debug builds:) * * linux/spinlock_api_up.h: * builds the _spin_*() APIs. * * linux/spinlock.h: builds the final spin_*() APIs. */ All SMP and UP architectures are converted by this patch. arm, i386, ia64, ppc, ppc64, s390/s390x, x64 was build-tested via crosscompilers. m32r, mips, sh, sparc, have not been tested yet, but should be mostly fine. From: Grant Grundler <grundler@parisc-linux.org> Booted and lightly tested on a500-44 (64-bit, SMP kernel, dual CPU). Builds 32-bit SMP kernel (not booted or tested). I did not try to build non-SMP kernels. That should be trivial to fix up later if necessary. I converted bit ops atomic_hash lock to raw_spinlock_t. Doing so avoids some ugly nesting of linux/*.h and asm/*.h files. Those particular locks are well tested and contained entirely inside arch specific code. I do NOT expect any new issues to arise with them. If someone does ever need to use debug/metrics with them, then they will need to unravel this hairball between spinlocks, atomic ops, and bit ops that exist only because parisc has exactly one atomic instruction: LDCW (load and clear word). From: "Luck, Tony" <tony.luck@intel.com> ia64 fix Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Arjan van de Ven <arjanv@infradead.org> Signed-off-by: Grant Grundler <grundler@parisc-linux.org> Cc: Matthew Wilcox <willy@debian.org> Signed-off-by: Hirokazu Takata <takata@linux-m32r.org> Signed-off-by: Mikael Pettersson <mikpe@csd.uu.se> Signed-off-by: Benoit Boissinot <benoit.boissinot@ens-lyon.org> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
257 lines
5.8 KiB
C
257 lines
5.8 KiB
C
/*
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* Copyright 2005, Red Hat, Inc., Ingo Molnar
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* Released under the General Public License (GPL).
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*
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* This file contains the spinlock/rwlock implementations for
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* DEBUG_SPINLOCK.
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*/
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#include <linux/config.h>
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#include <linux/spinlock.h>
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#include <linux/interrupt.h>
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#include <linux/delay.h>
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static void spin_bug(spinlock_t *lock, const char *msg)
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{
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static long print_once = 1;
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struct task_struct *owner = NULL;
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if (xchg(&print_once, 0)) {
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if (lock->owner && lock->owner != SPINLOCK_OWNER_INIT)
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owner = lock->owner;
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printk("BUG: spinlock %s on CPU#%d, %s/%d\n",
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msg, smp_processor_id(), current->comm, current->pid);
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printk(" lock: %p, .magic: %08x, .owner: %s/%d, .owner_cpu: %d\n",
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lock, lock->magic,
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owner ? owner->comm : "<none>",
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owner ? owner->pid : -1,
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lock->owner_cpu);
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dump_stack();
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#ifdef CONFIG_SMP
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/*
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* We cannot continue on SMP:
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*/
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// panic("bad locking");
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#endif
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}
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}
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#define SPIN_BUG_ON(cond, lock, msg) if (unlikely(cond)) spin_bug(lock, msg)
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static inline void debug_spin_lock_before(spinlock_t *lock)
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{
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SPIN_BUG_ON(lock->magic != SPINLOCK_MAGIC, lock, "bad magic");
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SPIN_BUG_ON(lock->owner == current, lock, "recursion");
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SPIN_BUG_ON(lock->owner_cpu == raw_smp_processor_id(),
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lock, "cpu recursion");
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}
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static inline void debug_spin_lock_after(spinlock_t *lock)
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{
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lock->owner_cpu = raw_smp_processor_id();
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lock->owner = current;
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}
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static inline void debug_spin_unlock(spinlock_t *lock)
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{
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SPIN_BUG_ON(lock->magic != SPINLOCK_MAGIC, lock, "bad magic");
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SPIN_BUG_ON(!spin_is_locked(lock), lock, "already unlocked");
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SPIN_BUG_ON(lock->owner != current, lock, "wrong owner");
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SPIN_BUG_ON(lock->owner_cpu != raw_smp_processor_id(),
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lock, "wrong CPU");
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lock->owner = SPINLOCK_OWNER_INIT;
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lock->owner_cpu = -1;
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}
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static void __spin_lock_debug(spinlock_t *lock)
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{
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int print_once = 1;
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u64 i;
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for (;;) {
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for (i = 0; i < loops_per_jiffy * HZ; i++) {
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cpu_relax();
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if (__raw_spin_trylock(&lock->raw_lock))
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return;
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}
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/* lockup suspected: */
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if (print_once) {
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print_once = 0;
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printk("BUG: spinlock lockup on CPU#%d, %s/%d, %p\n",
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smp_processor_id(), current->comm, current->pid,
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lock);
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dump_stack();
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}
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}
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}
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void _raw_spin_lock(spinlock_t *lock)
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{
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debug_spin_lock_before(lock);
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if (unlikely(!__raw_spin_trylock(&lock->raw_lock)))
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__spin_lock_debug(lock);
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debug_spin_lock_after(lock);
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}
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int _raw_spin_trylock(spinlock_t *lock)
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{
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int ret = __raw_spin_trylock(&lock->raw_lock);
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if (ret)
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debug_spin_lock_after(lock);
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#ifndef CONFIG_SMP
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/*
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* Must not happen on UP:
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*/
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SPIN_BUG_ON(!ret, lock, "trylock failure on UP");
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#endif
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return ret;
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}
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void _raw_spin_unlock(spinlock_t *lock)
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{
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debug_spin_unlock(lock);
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__raw_spin_unlock(&lock->raw_lock);
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}
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static void rwlock_bug(rwlock_t *lock, const char *msg)
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{
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static long print_once = 1;
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if (xchg(&print_once, 0)) {
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printk("BUG: rwlock %s on CPU#%d, %s/%d, %p\n", msg,
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smp_processor_id(), current->comm, current->pid, lock);
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dump_stack();
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#ifdef CONFIG_SMP
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/*
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* We cannot continue on SMP:
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*/
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panic("bad locking");
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#endif
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}
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}
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#define RWLOCK_BUG_ON(cond, lock, msg) if (unlikely(cond)) rwlock_bug(lock, msg)
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static void __read_lock_debug(rwlock_t *lock)
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{
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int print_once = 1;
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u64 i;
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for (;;) {
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for (i = 0; i < loops_per_jiffy * HZ; i++) {
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cpu_relax();
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if (__raw_read_trylock(&lock->raw_lock))
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return;
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}
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/* lockup suspected: */
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if (print_once) {
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print_once = 0;
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printk("BUG: read-lock lockup on CPU#%d, %s/%d, %p\n",
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smp_processor_id(), current->comm, current->pid,
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lock);
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dump_stack();
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}
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}
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}
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void _raw_read_lock(rwlock_t *lock)
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{
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RWLOCK_BUG_ON(lock->magic != RWLOCK_MAGIC, lock, "bad magic");
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if (unlikely(!__raw_read_trylock(&lock->raw_lock)))
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__read_lock_debug(lock);
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}
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int _raw_read_trylock(rwlock_t *lock)
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{
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int ret = __raw_read_trylock(&lock->raw_lock);
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#ifndef CONFIG_SMP
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/*
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* Must not happen on UP:
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*/
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RWLOCK_BUG_ON(!ret, lock, "trylock failure on UP");
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#endif
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return ret;
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}
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void _raw_read_unlock(rwlock_t *lock)
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{
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RWLOCK_BUG_ON(lock->magic != RWLOCK_MAGIC, lock, "bad magic");
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__raw_read_unlock(&lock->raw_lock);
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}
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static inline void debug_write_lock_before(rwlock_t *lock)
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{
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RWLOCK_BUG_ON(lock->magic != RWLOCK_MAGIC, lock, "bad magic");
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RWLOCK_BUG_ON(lock->owner == current, lock, "recursion");
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RWLOCK_BUG_ON(lock->owner_cpu == raw_smp_processor_id(),
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lock, "cpu recursion");
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}
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static inline void debug_write_lock_after(rwlock_t *lock)
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{
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lock->owner_cpu = raw_smp_processor_id();
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lock->owner = current;
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}
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static inline void debug_write_unlock(rwlock_t *lock)
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{
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RWLOCK_BUG_ON(lock->magic != RWLOCK_MAGIC, lock, "bad magic");
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RWLOCK_BUG_ON(lock->owner != current, lock, "wrong owner");
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RWLOCK_BUG_ON(lock->owner_cpu != raw_smp_processor_id(),
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lock, "wrong CPU");
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lock->owner = SPINLOCK_OWNER_INIT;
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lock->owner_cpu = -1;
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}
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static void __write_lock_debug(rwlock_t *lock)
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{
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int print_once = 1;
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u64 i;
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for (;;) {
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for (i = 0; i < loops_per_jiffy * HZ; i++) {
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cpu_relax();
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if (__raw_write_trylock(&lock->raw_lock))
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return;
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}
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/* lockup suspected: */
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if (print_once) {
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print_once = 0;
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printk("BUG: write-lock lockup on CPU#%d, %s/%d, %p\n",
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smp_processor_id(), current->comm, current->pid,
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lock);
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dump_stack();
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}
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}
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}
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void _raw_write_lock(rwlock_t *lock)
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{
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debug_write_lock_before(lock);
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if (unlikely(!__raw_write_trylock(&lock->raw_lock)))
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__write_lock_debug(lock);
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debug_write_lock_after(lock);
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}
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int _raw_write_trylock(rwlock_t *lock)
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{
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int ret = __raw_write_trylock(&lock->raw_lock);
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if (ret)
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debug_write_lock_after(lock);
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#ifndef CONFIG_SMP
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/*
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* Must not happen on UP:
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*/
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RWLOCK_BUG_ON(!ret, lock, "trylock failure on UP");
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#endif
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return ret;
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}
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void _raw_write_unlock(rwlock_t *lock)
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{
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debug_write_unlock(lock);
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__raw_write_unlock(&lock->raw_lock);
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}
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