Re: status of Linux on Alpha?
From: Marc Giger
Date: Tue Apr 27 2004 - 13:04:00 EST
Hi Eric,
On 27 Apr 2004 12:23:22 -0500
Eric Sandeen <sandeen@xxxxxxx> wrote:
> Marc, do you have a patch associated with the changeset you found to
> be the culprit?
>
> I don't know how to get from that changeset number to a diff.
Yep, you will find all changesets and the belonging patches on
http://linux.bkbits.net:8080/linux-2.5
Reverting the following patch and all is fine...
# This is a BitKeeper generated diff -Nru style patch.
#
# ChangeSet
# 2004/02/27 18:17:12+11:00 nathans@xxxxxxx
# [XFS] Implement mrlocks on top of rwsems, instead of using our own
mrlock code.#
# SGI Modid: xfs-linux:xfs-kern:167181a
#
# BitKeeper/deleted/.del-mrlock.c~4fd914a7832bd60d
# 2004/02/27 18:16:18+11:00 nathans@xxxxxxx +0 -0
# Delete: fs/xfs/linux/mrlock.c
#
# fs/xfs/Makefile
# 2004/02/27 18:16:53+11:00 nathans@xxxxxxx +0 -1
# [XFS] Implement mrlocks on top of rwsems, instead of using our own
mrlock code.#
# fs/xfs/linux/mrlock.h
# 2004/02/27 18:16:53+11:00 nathans@xxxxxxx +62 -45
# [XFS] Implement mrlocks on top of rwsems, instead of using our own
mrlock code.#
diff -Nru a/fs/xfs/Makefile b/fs/xfs/Makefile
--- a/fs/xfs/Makefile Mon Apr 12 08:43:27 2004
+++ b/fs/xfs/Makefile Mon Apr 12 08:43:27 2004
@@ -130,7 +130,6 @@
# Objects in linux/
xfs-y += $(addprefix linux/, \
- mrlock.o \
xfs_aops.o \
xfs_buf.o \
xfs_file.o \
diff -Nru a/fs/xfs/linux/mrlock.c b/fs/xfs/linux/mrlock.c
--- a/fs/xfs/linux/mrlock.c Mon Apr 12 08:43:27 2004
+++ /dev/null Wed Dec 31 16:00:00 1969
@@ -1,274 +0,0 @@
-/*
- * Copyright (c) 2000-2003 Silicon Graphics, Inc. All Rights Reserved.
- *
- * This program is free software; you can redistribute it and/or modify
it- * under the terms of version 2 of the GNU General Public License as
- * published by the Free Software Foundation.
- *
- * This program is distributed in the hope that it would be useful, but
- * WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
- *
- * Further, this software is distributed without any warranty that it
is- * free of the rightful claim of any third person regarding
infringement- * or the like. Any license provided herein, whether
implied or- * otherwise, applies only to this software file. Patent
licenses, if- * any, provided herein do not apply to combinations of
this program with- * other software, or any other product whatsoever.
- *
- * You should have received a copy of the GNU General Public License
along- * with this program; if not, write the Free Software Foundation,
Inc., 59- * Temple Place - Suite 330, Boston MA 02111-1307, USA.
- *
- * Contact information: Silicon Graphics, Inc., 1600 Amphitheatre Pkwy,
- * Mountain View, CA 94043, or:
- *
- * http://www.sgi.com
- *
- * For further information regarding this notice, see:
- *
- * http://oss.sgi.com/projects/GenInfo/SGIGPLNoticeExplan/
- */
-
-#include <linux/time.h>
-#include <linux/sched.h>
-#include <asm/system.h>
-#include <linux/interrupt.h>
-#include <asm/current.h>
-
-#include "mrlock.h"
-
-
-#if USE_RW_WAIT_QUEUE_SPINLOCK
-# define wq_write_lock write_lock
-#else
-# define wq_write_lock spin_lock
-#endif
-
-/*
- * We don't seem to need lock_type (only one supported), name, or
- * sequence. But, XFS will pass it so let's leave them here for now.
- */
-/* ARGSUSED */
-void
-mrlock_init(mrlock_t *mrp, int lock_type, char *name, long sequence)
-{
- mrp->mr_count = 0;
- mrp->mr_reads_waiting = 0;
- mrp->mr_writes_waiting = 0;
- init_waitqueue_head(&mrp->mr_readerq);
- init_waitqueue_head(&mrp->mr_writerq);
- mrp->mr_lock = SPIN_LOCK_UNLOCKED;
-}
-
-/*
- * Macros to lock/unlock the mrlock_t.
- */
-
-#define MRLOCK(m) spin_lock(&(m)->mr_lock);
-#define MRUNLOCK(m) spin_unlock(&(m)->mr_lock);
-
-
-/*
- * lock_wait should never be called in an interrupt thread.
- *
- * mrlocks can sleep (i.e. call schedule) and so they can't ever
- * be called from an interrupt thread.
- *
- * threads that wake-up should also never be invoked from interrupt
threads.- *
- * But, waitqueue_lock is locked from interrupt threads - and we are
- * called with interrupts disabled, so it is all OK.
- */
-
-/* ARGSUSED */
-void
-lock_wait(wait_queue_head_t *q, spinlock_t *lock, int rw)
-{
- DECLARE_WAITQUEUE( wait, current );
-
- __set_current_state(TASK_UNINTERRUPTIBLE);
-
- spin_lock(&q->lock);
- if (rw) {
- __add_wait_queue_tail(q, &wait);
- } else {
- __add_wait_queue(q, &wait);
- }
-
- spin_unlock(&q->lock);
- spin_unlock(lock);
-
- schedule();
-
- spin_lock(&q->lock);
- __remove_wait_queue(q, &wait);
- spin_unlock(&q->lock);
-
- spin_lock(lock);
-
- /* return with lock held */
-}
-
-/* ARGSUSED */
-void
-mrfree(mrlock_t *mrp)
-{
-}
-
-/* ARGSUSED */
-void
-mrlock(mrlock_t *mrp, int type, int flags)
-{
- if (type == MR_ACCESS)
- mraccess(mrp);
- else
- mrupdate(mrp);
-}
-
-/* ARGSUSED */
-void
-mraccessf(mrlock_t *mrp, int flags)
-{
- MRLOCK(mrp);
- if(mrp->mr_writes_waiting > 0) {
- mrp->mr_reads_waiting++;
- lock_wait(&mrp->mr_readerq, &mrp->mr_lock, 0);
- mrp->mr_reads_waiting--;
- }
- while (mrp->mr_count < 0) {
- mrp->mr_reads_waiting++;
- lock_wait(&mrp->mr_readerq, &mrp->mr_lock, 0);
- mrp->mr_reads_waiting--;
- }
- mrp->mr_count++;
- MRUNLOCK(mrp);
-}
-
-/* ARGSUSED */
-void
-mrupdatef(mrlock_t *mrp, int flags)
-{
- MRLOCK(mrp);
- while(mrp->mr_count) {
- mrp->mr_writes_waiting++;
- lock_wait(&mrp->mr_writerq, &mrp->mr_lock, 1);
- mrp->mr_writes_waiting--;
- }
-
- mrp->mr_count = -1; /* writer on it */
- MRUNLOCK(mrp);
-}
-
-int
-mrtryaccess(mrlock_t *mrp)
-{
- MRLOCK(mrp);
- /*
- * If anyone is waiting for update access or the lock is held for
update- * fail the request.
- */
- if(mrp->mr_writes_waiting > 0 || mrp->mr_count < 0) {
- MRUNLOCK(mrp);
- return 0;
- }
- mrp->mr_count++;
- MRUNLOCK(mrp);
- return 1;
-}
-
-int
-mrtrypromote(mrlock_t *mrp)
-{
- MRLOCK(mrp);
-
- if(mrp->mr_count == 1) { /* We are the only thread with the lock */
- mrp->mr_count = -1; /* writer on it */
- MRUNLOCK(mrp);
- return 1;
- }
-
- MRUNLOCK(mrp);
- return 0;
-}
-
-int
-mrtryupdate(mrlock_t *mrp)
-{
- MRLOCK(mrp);
-
- if(mrp->mr_count) {
- MRUNLOCK(mrp);
- return 0;
- }
-
- mrp->mr_count = -1; /* writer on it */
- MRUNLOCK(mrp);
- return 1;
-}
-
-static __inline__ void mrwake(mrlock_t *mrp)
-{
- /*
- * First, if the count is now 0, we need to wake-up anyone waiting.
- */
- if (!mrp->mr_count) {
- if (mrp->mr_writes_waiting) { /* Wake-up first writer waiting
*/- wake_up(&mrp->mr_writerq);
- } else if (mrp->mr_reads_waiting) { /* Wakeup any readers
waiting */- wake_up(&mrp->mr_readerq);
- }
- }
-}
-
-void
-mraccunlock(mrlock_t *mrp)
-{
- MRLOCK(mrp);
- mrp->mr_count--;
- mrwake(mrp);
- MRUNLOCK(mrp);
-}
-
-void
-mrunlock(mrlock_t *mrp)
-{
- MRLOCK(mrp);
- if (mrp->mr_count < 0) {
- mrp->mr_count = 0;
- } else {
- mrp->mr_count--;
- }
- mrwake(mrp);
- MRUNLOCK(mrp);
-}
-
-int
-ismrlocked(mrlock_t *mrp, int type) /* No need to lock since info can change
*/-{
- if (type == MR_ACCESS)
- return (mrp->mr_count > 0); /* Read lock */
- else if (type == MR_UPDATE)
- return (mrp->mr_count < 0); /* Write lock */
- else if (type == (MR_UPDATE | MR_ACCESS))
- return (mrp->mr_count); /* Any type of lock held */
- else /* Any waiters */
- return (mrp->mr_reads_waiting | mrp->mr_writes_waiting);
-}
-
-/*
- * Demote from update to access. We better be the only thread with the
- * lock in update mode so it should be easy to set to 1.
- * Wake-up any readers waiting.
- */
-
-void
-mrdemote(mrlock_t *mrp)
-{
- MRLOCK(mrp);
- mrp->mr_count = 1;
- if (mrp->mr_reads_waiting) { /* Wakeup all readers waiting */
- wake_up(&mrp->mr_readerq);
- }
- MRUNLOCK(mrp);
-}
diff -Nru a/fs/xfs/linux/mrlock.h b/fs/xfs/linux/mrlock.h
--- a/fs/xfs/linux/mrlock.h Mon Apr 12 08:43:27 2004
+++ b/fs/xfs/linux/mrlock.h Mon Apr 12 08:43:27 2004
@@ -1,5 +1,5 @@
/*
- * Copyright (c) 2000-2003 Silicon Graphics, Inc. All Rights Reserved.
+ * Copyright (c) 2000-2004 Silicon Graphics, Inc. All Rights Reserved.
*
* This program is free software; you can redistribute it and/or modify
it * under the terms of version 2 of the GNU General Public License as
@@ -32,56 +32,73 @@
#ifndef __XFS_SUPPORT_MRLOCK_H__
#define __XFS_SUPPORT_MRLOCK_H__
-#include <linux/time.h>
-#include <linux/wait.h>
-#include <asm/atomic.h>
-#include <asm/semaphore.h>
+#include <linux/rwsem.h>
-/*
- * Implement mrlocks on Linux that work for XFS.
- *
- * These are sleep locks and not spinlocks. If one wants read/write
spinlocks,- * use read_lock, write_lock, ... see spinlock.h.
- */
+enum { MR_NONE, MR_ACCESS, MR_UPDATE };
-typedef struct mrlock_s {
- int mr_count;
- unsigned short mr_reads_waiting;
- unsigned short mr_writes_waiting;
- wait_queue_head_t mr_readerq;
- wait_queue_head_t mr_writerq;
- spinlock_t mr_lock;
+typedef struct {
+ struct rw_semaphore mr_lock;
+ int mr_writer;
} mrlock_t;
-#define MR_ACCESS 1
-#define MR_UPDATE 2
-
-#define MRLOCK_BARRIER 0x1
-#define MRLOCK_ALLOW_EQUAL_PRI 0x8
+#define mrinit(mrp, name) \
+ ( (mrp)->mr_writer = 0, init_rwsem(&(mrp)->mr_lock) )
+#define mrlock_init(mrp, t,n,s) mrinit(mrp, n)
+#define mrfree(mrp) do { } while (0)
+#define mraccess(mrp) mraccessf(mrp, 0)
+#define mrupdate(mrp) mrupdatef(mrp, 0)
+
+static inline void mraccessf(mrlock_t *mrp, int flags)
+{
+ down_read(&mrp->mr_lock);
+}
+
+static inline void mrupdatef(mrlock_t *mrp, int flags)
+{
+ down_write(&mrp->mr_lock);
+ mrp->mr_writer = 1;
+}
+
+static inline int mrtryaccess(mrlock_t *mrp)
+{
+ return down_read_trylock(&mrp->mr_lock);
+}
+
+static inline int mrtryupdate(mrlock_t *mrp)
+{
+ if (!down_write_trylock(&mrp->mr_lock))
+ return 0;
+ mrp->mr_writer = 1;
+ return 1;
+}
+
+static inline void mrunlock(mrlock_t *mrp)
+{
+ if (mrp->mr_writer) {
+ mrp->mr_writer = 0;
+ up_write(&mrp->mr_lock);
+ } else {
+ up_read(&mrp->mr_lock);
+ }
+}
+
+static inline void mrdemote(mrlock_t *mrp)
+{
+ mrp->mr_writer = 0;
+ downgrade_write(&mrp->mr_lock);
+}
/*
- * mraccessf/mrupdatef take flags to be passed in while sleeping;
- * only PLTWAIT is currently supported.
+ * Debug-only routine, without some platform-specific asm code, we can
+ * now only answer requests regarding whether we hold the lock for
write+ * (reader state is outside our visibility, we only track writer
state).+ * Note: means !ismrlocked would give false positivies, so don't
do that. */
-
-extern void mraccessf(mrlock_t *, int);
-extern void mrupdatef(mrlock_t *, int);
-extern void mrlock(mrlock_t *, int, int);
-extern void mrunlock(mrlock_t *);
-extern void mraccunlock(mrlock_t *);
-extern int mrtryupdate(mrlock_t *);
-extern int mrtryaccess(mrlock_t *);
-extern int mrtrypromote(mrlock_t *);
-extern void mrdemote(mrlock_t *);
-
-extern int ismrlocked(mrlock_t *, int);
-extern void mrlock_init(mrlock_t *, int type, char *name, long
sequence);-extern void mrfree(mrlock_t *);
-
-#define mrinit(mrp, name) mrlock_init(mrp, MRLOCK_BARRIER, name, -1)
-#define mraccess(mrp) mraccessf(mrp, 0) /* grab for READ/ACCESS */
-#define mrupdate(mrp) mrupdatef(mrp, 0) /* grab for WRITE/UPDATE */
-#define mrislocked_access(mrp) ((mrp)->mr_count > 0)
-#define mrislocked_update(mrp) ((mrp)->mr_count < 0)
+static inline int ismrlocked(mrlock_t *mrp, int type)
+{
+ if (type == MR_UPDATE)
+ return mrp->mr_writer;
+ return 1;
+}
#endif /* __XFS_SUPPORT_MRLOCK_H__ */
-
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