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linux-next/fs/xfs/xfs_error.h
Dave Chinner 73efe4a4dd xfs: prevent NMI timeouts in cmn_err 
We currently have a global error message buffer in cmn_err that is
protected by a spin lock that disables interrupts.  Recently there
have been reports of NMI timeouts occurring when the console is
being flooded by SCSI error reports due to cmn_err() getting stuck
trying to print to the console while holding this lock (i.e. with
interrupts disabled). The NMI watchdog is seeing this CPU as
non-responding and so is triggering a panic.  While the trigger for
the reported case is SCSI errors, pretty much anything that spams
the kernel log could cause this to occur.

Realistically the only reason that we have the intemediate message
buffer is to prepend the correct kernel log level prefix to the log
message. The only reason we have the lock is to protect the global
message buffer and the only reason the message buffer is global is
to keep it off the stack. Hence if we can avoid needing a global
message buffer we avoid needing the lock, and we can do this with a
small amount of cleanup and some preprocessor tricks:

	1. clean up xfs_cmn_err() panic mask functionality to avoid
	   needing debug code in xfs_cmn_err()
	2. remove the couple of "!" message prefixes that still exist that
	   the existing cmn_err() code steps over.
	3. redefine CE_* levels directly to KERN_*
	4. redefine cmn_err() and friends to use printk() directly
	   via variable argument length macros.

By doing this, we can completely remove the cmn_err() code and the
lock that is causing the problems, and rely solely on printk()
serialisation to ensure that we don't get garbled messages.

A series of followup patches is really needed to clean up all the
cmn_err() calls and related messages properly, but that results in a
series that is not easily back portable to enterprise kernels. Hence
this initial fix is only to address the direct problem in the lowest
impact way possible.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Alex Elder <aelder@sgi.com>
2011-01-12 08:46:41 -06:00

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/*
* Copyright (c) 2000-2002,2005 Silicon Graphics, Inc.
* All Rights Reserved.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms 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. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
#ifndef __XFS_ERROR_H__
#define __XFS_ERROR_H__
#ifdef DEBUG
#define XFS_ERROR_NTRAP 10
extern int xfs_etrap[XFS_ERROR_NTRAP];
extern int xfs_error_trap(int);
#define XFS_ERROR(e) xfs_error_trap(e)
#else
#define XFS_ERROR(e) (e)
#endif
struct xfs_mount;
extern void xfs_error_report(const char *tag, int level, struct xfs_mount *mp,
const char *filename, int linenum, inst_t *ra);
extern void xfs_corruption_error(const char *tag, int level,
struct xfs_mount *mp, void *p, const char *filename,
int linenum, inst_t *ra);
#define XFS_ERROR_REPORT(e, lvl, mp) \
xfs_error_report(e, lvl, mp, __FILE__, __LINE__, __return_address)
#define XFS_CORRUPTION_ERROR(e, lvl, mp, mem) \
xfs_corruption_error(e, lvl, mp, mem, \
__FILE__, __LINE__, __return_address)
#define XFS_ERRLEVEL_OFF 0
#define XFS_ERRLEVEL_LOW 1
#define XFS_ERRLEVEL_HIGH 5
/*
* Macros to set EFSCORRUPTED & return/branch.
*/
#define XFS_WANT_CORRUPTED_GOTO(x,l) \
{ \
int fs_is_ok = (x); \
ASSERT(fs_is_ok); \
if (unlikely(!fs_is_ok)) { \
XFS_ERROR_REPORT("XFS_WANT_CORRUPTED_GOTO", \
XFS_ERRLEVEL_LOW, NULL); \
error = XFS_ERROR(EFSCORRUPTED); \
goto l; \
} \
}
#define XFS_WANT_CORRUPTED_RETURN(x) \
{ \
int fs_is_ok = (x); \
ASSERT(fs_is_ok); \
if (unlikely(!fs_is_ok)) { \
XFS_ERROR_REPORT("XFS_WANT_CORRUPTED_RETURN", \
XFS_ERRLEVEL_LOW, NULL); \
return XFS_ERROR(EFSCORRUPTED); \
} \
}
/*
* error injection tags - the labels can be anything you want
* but each tag should have its own unique number
*/
#define XFS_ERRTAG_NOERROR 0
#define XFS_ERRTAG_IFLUSH_1 1
#define XFS_ERRTAG_IFLUSH_2 2
#define XFS_ERRTAG_IFLUSH_3 3
#define XFS_ERRTAG_IFLUSH_4 4
#define XFS_ERRTAG_IFLUSH_5 5
#define XFS_ERRTAG_IFLUSH_6 6
#define XFS_ERRTAG_DA_READ_BUF 7
#define XFS_ERRTAG_BTREE_CHECK_LBLOCK 8
#define XFS_ERRTAG_BTREE_CHECK_SBLOCK 9
#define XFS_ERRTAG_ALLOC_READ_AGF 10
#define XFS_ERRTAG_IALLOC_READ_AGI 11
#define XFS_ERRTAG_ITOBP_INOTOBP 12
#define XFS_ERRTAG_IUNLINK 13
#define XFS_ERRTAG_IUNLINK_REMOVE 14
#define XFS_ERRTAG_DIR_INO_VALIDATE 15
#define XFS_ERRTAG_BULKSTAT_READ_CHUNK 16
#define XFS_ERRTAG_IODONE_IOERR 17
#define XFS_ERRTAG_STRATREAD_IOERR 18
#define XFS_ERRTAG_STRATCMPL_IOERR 19
#define XFS_ERRTAG_DIOWRITE_IOERR 20
#define XFS_ERRTAG_BMAPIFORMAT 21
#define XFS_ERRTAG_MAX 22
/*
* Random factors for above tags, 1 means always, 2 means 1/2 time, etc.
*/
#define XFS_RANDOM_DEFAULT 100
#define XFS_RANDOM_IFLUSH_1 XFS_RANDOM_DEFAULT
#define XFS_RANDOM_IFLUSH_2 XFS_RANDOM_DEFAULT
#define XFS_RANDOM_IFLUSH_3 XFS_RANDOM_DEFAULT
#define XFS_RANDOM_IFLUSH_4 XFS_RANDOM_DEFAULT
#define XFS_RANDOM_IFLUSH_5 XFS_RANDOM_DEFAULT
#define XFS_RANDOM_IFLUSH_6 XFS_RANDOM_DEFAULT
#define XFS_RANDOM_DA_READ_BUF XFS_RANDOM_DEFAULT
#define XFS_RANDOM_BTREE_CHECK_LBLOCK (XFS_RANDOM_DEFAULT/4)
#define XFS_RANDOM_BTREE_CHECK_SBLOCK XFS_RANDOM_DEFAULT
#define XFS_RANDOM_ALLOC_READ_AGF XFS_RANDOM_DEFAULT
#define XFS_RANDOM_IALLOC_READ_AGI XFS_RANDOM_DEFAULT
#define XFS_RANDOM_ITOBP_INOTOBP XFS_RANDOM_DEFAULT
#define XFS_RANDOM_IUNLINK XFS_RANDOM_DEFAULT
#define XFS_RANDOM_IUNLINK_REMOVE XFS_RANDOM_DEFAULT
#define XFS_RANDOM_DIR_INO_VALIDATE XFS_RANDOM_DEFAULT
#define XFS_RANDOM_BULKSTAT_READ_CHUNK XFS_RANDOM_DEFAULT
#define XFS_RANDOM_IODONE_IOERR (XFS_RANDOM_DEFAULT/10)
#define XFS_RANDOM_STRATREAD_IOERR (XFS_RANDOM_DEFAULT/10)
#define XFS_RANDOM_STRATCMPL_IOERR (XFS_RANDOM_DEFAULT/10)
#define XFS_RANDOM_DIOWRITE_IOERR (XFS_RANDOM_DEFAULT/10)
#define XFS_RANDOM_BMAPIFORMAT XFS_RANDOM_DEFAULT
#ifdef DEBUG
extern int xfs_error_test_active;
extern int xfs_error_test(int, int *, char *, int, char *, unsigned long);
#define XFS_NUM_INJECT_ERROR 10
#define XFS_TEST_ERROR(expr, mp, tag, rf) \
((expr) || (xfs_error_test_active && \
xfs_error_test((tag), (mp)->m_fixedfsid, "expr", __LINE__, __FILE__, \
(rf))))
extern int xfs_errortag_add(int error_tag, struct xfs_mount *mp);
extern int xfs_errortag_clearall(struct xfs_mount *mp, int loud);
#else
#define XFS_TEST_ERROR(expr, mp, tag, rf) (expr)
#define xfs_errortag_add(tag, mp) (ENOSYS)
#define xfs_errortag_clearall(mp, loud) (ENOSYS)
#endif /* DEBUG */
/*
* XFS panic tags -- allow a call to xfs_cmn_err() be turned into
* a panic by setting xfs_panic_mask in a
* sysctl. update xfs_max[XFS_PARAM] if
* more are added.
*/
#define XFS_NO_PTAG 0
#define XFS_PTAG_IFLUSH 0x00000001
#define XFS_PTAG_LOGRES 0x00000002
#define XFS_PTAG_AILDELETE 0x00000004
#define XFS_PTAG_ERROR_REPORT 0x00000008
#define XFS_PTAG_SHUTDOWN_CORRUPT 0x00000010
#define XFS_PTAG_SHUTDOWN_IOERROR 0x00000020
#define XFS_PTAG_SHUTDOWN_LOGERROR 0x00000040
#define XFS_PTAG_FSBLOCK_ZERO 0x00000080
struct xfs_mount;
extern void xfs_hex_dump(void *p, int length);
#define xfs_fs_repair_cmn_err(level, mp, fmt, args...) \
xfs_fs_cmn_err(level, mp, fmt " Unmount and run xfs_repair.", ## args)
#define xfs_fs_mount_cmn_err(f, fmt, args...) \
do { \
if (!(f & XFS_MFSI_QUIET)) \
cmn_err(CE_WARN, "XFS: " fmt, ## args); \
} while (0)
#endif /* __XFS_ERROR_H__ */
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