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fb1c8f93d8
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>
95 lines
2.6 KiB
C
95 lines
2.6 KiB
C
/*
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* Spin and read/write lock operations.
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*
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* Copyright (C) 2001-2004 Paul Mackerras <paulus@au.ibm.com>, IBM
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* Copyright (C) 2001 Anton Blanchard <anton@au.ibm.com>, IBM
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* Copyright (C) 2002 Dave Engebretsen <engebret@us.ibm.com>, IBM
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* Rework to support virtual processors
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*/
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#include <linux/config.h>
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#include <linux/kernel.h>
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#include <linux/spinlock.h>
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#include <linux/module.h>
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#include <linux/stringify.h>
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#include <asm/hvcall.h>
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#include <asm/iSeries/HvCall.h>
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/* waiting for a spinlock... */
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#if defined(CONFIG_PPC_SPLPAR) || defined(CONFIG_PPC_ISERIES)
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void __spin_yield(raw_spinlock_t *lock)
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{
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unsigned int lock_value, holder_cpu, yield_count;
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struct paca_struct *holder_paca;
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lock_value = lock->slock;
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if (lock_value == 0)
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return;
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holder_cpu = lock_value & 0xffff;
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BUG_ON(holder_cpu >= NR_CPUS);
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holder_paca = &paca[holder_cpu];
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yield_count = holder_paca->lppaca.yield_count;
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if ((yield_count & 1) == 0)
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return; /* virtual cpu is currently running */
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rmb();
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if (lock->slock != lock_value)
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return; /* something has changed */
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#ifdef CONFIG_PPC_ISERIES
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HvCall2(HvCallBaseYieldProcessor, HvCall_YieldToProc,
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((u64)holder_cpu << 32) | yield_count);
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#else
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plpar_hcall_norets(H_CONFER, get_hard_smp_processor_id(holder_cpu),
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yield_count);
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#endif
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}
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/*
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* Waiting for a read lock or a write lock on a rwlock...
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* This turns out to be the same for read and write locks, since
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* we only know the holder if it is write-locked.
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*/
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void __rw_yield(raw_rwlock_t *rw)
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{
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int lock_value;
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unsigned int holder_cpu, yield_count;
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struct paca_struct *holder_paca;
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lock_value = rw->lock;
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if (lock_value >= 0)
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return; /* no write lock at present */
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holder_cpu = lock_value & 0xffff;
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BUG_ON(holder_cpu >= NR_CPUS);
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holder_paca = &paca[holder_cpu];
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yield_count = holder_paca->lppaca.yield_count;
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if ((yield_count & 1) == 0)
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return; /* virtual cpu is currently running */
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rmb();
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if (rw->lock != lock_value)
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return; /* something has changed */
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#ifdef CONFIG_PPC_ISERIES
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HvCall2(HvCallBaseYieldProcessor, HvCall_YieldToProc,
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((u64)holder_cpu << 32) | yield_count);
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#else
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plpar_hcall_norets(H_CONFER, get_hard_smp_processor_id(holder_cpu),
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yield_count);
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#endif
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}
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#endif
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void __raw_spin_unlock_wait(raw_spinlock_t *lock)
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{
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while (lock->slock) {
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HMT_low();
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if (SHARED_PROCESSOR)
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__spin_yield(lock);
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}
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HMT_medium();
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}
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EXPORT_SYMBOL(__raw_spin_unlock_wait);
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