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authorIngo Molnar <mingo@elte.hu>2005-09-10 11:25:56 +0400
committerLinus Torvalds <torvalds@g5.osdl.org>2005-09-10 21:06:21 +0400
commitfb1c8f93d869b34cacb8b8932e2b83d96a19d720 (patch)
treea006d078aa02e421a7dc4793c335308204859d36 /include/linux/spinlock_up.h
parent4327edf6b8a7ac7dce144313947995538842d8fd (diff)
downloadlinux-fb1c8f93d869b34cacb8b8932e2b83d96a19d720.tar.xz
[PATCH] spinlock consolidation
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>
Diffstat (limited to 'include/linux/spinlock_up.h')
-rw-r--r--include/linux/spinlock_up.h74
1 files changed, 74 insertions, 0 deletions
diff --git a/include/linux/spinlock_up.h b/include/linux/spinlock_up.h
new file mode 100644
index 000000000000..31accf2f0b13
--- /dev/null
+++ b/include/linux/spinlock_up.h
@@ -0,0 +1,74 @@
+#ifndef __LINUX_SPINLOCK_UP_H
+#define __LINUX_SPINLOCK_UP_H
+
+#ifndef __LINUX_SPINLOCK_H
+# error "please don't include this file directly"
+#endif
+
+/*
+ * include/linux/spinlock_up.h - UP-debug version of spinlocks.
+ *
+ * portions Copyright 2005, Red Hat, Inc., Ingo Molnar
+ * Released under the General Public License (GPL).
+ *
+ * In the debug case, 1 means unlocked, 0 means locked. (the values
+ * are inverted, to catch initialization bugs)
+ *
+ * No atomicity anywhere, we are on UP.
+ */
+
+#ifdef CONFIG_DEBUG_SPINLOCK
+
+#define __raw_spin_is_locked(x) ((x)->slock == 0)
+
+static inline void __raw_spin_lock(raw_spinlock_t *lock)
+{
+ lock->slock = 0;
+}
+
+static inline void
+__raw_spin_lock_flags(raw_spinlock_t *lock, unsigned long flags)
+{
+ local_irq_save(flags);
+ lock->slock = 0;
+}
+
+static inline int __raw_spin_trylock(raw_spinlock_t *lock)
+{
+ char oldval = lock->slock;
+
+ lock->slock = 0;
+
+ return oldval > 0;
+}
+
+static inline void __raw_spin_unlock(raw_spinlock_t *lock)
+{
+ lock->slock = 1;
+}
+
+/*
+ * Read-write spinlocks. No debug version.
+ */
+#define __raw_read_lock(lock) do { (void)(lock); } while (0)
+#define __raw_write_lock(lock) do { (void)(lock); } while (0)
+#define __raw_read_trylock(lock) ({ (void)(lock); 1; })
+#define __raw_write_trylock(lock) ({ (void)(lock); 1; })
+#define __raw_read_unlock(lock) do { (void)(lock); } while (0)
+#define __raw_write_unlock(lock) do { (void)(lock); } while (0)
+
+#else /* DEBUG_SPINLOCK */
+#define __raw_spin_is_locked(lock) ((void)(lock), 0)
+/* for sched.c and kernel_lock.c: */
+# define __raw_spin_lock(lock) do { (void)(lock); } while (0)
+# define __raw_spin_unlock(lock) do { (void)(lock); } while (0)
+# define __raw_spin_trylock(lock) ({ (void)(lock); 1; })
+#endif /* DEBUG_SPINLOCK */
+
+#define __raw_read_can_lock(lock) (((void)(lock), 1))
+#define __raw_write_can_lock(lock) (((void)(lock), 1))
+
+#define __raw_spin_unlock_wait(lock) \
+ do { cpu_relax(); } while (__raw_spin_is_locked(lock))
+
+#endif /* __LINUX_SPINLOCK_UP_H */