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authorDave Chinner <dchinner@redhat.com>2011-01-12 00:35:42 +0000
committerAlex Elder <aelder@sgi.com>2011-01-12 08:46:41 -0600
commit73efe4a4ddf8eb2b1cc7039e8a66a23a424961af (patch)
tree1c3eed2bed48cf62a476cf0b34e66211ae29d00f /fs/xfs/xfs_error.h
parent65a84a0f7567ea244e5246e642920260cfc2744a (diff)
downloadop-kernel-dev-73efe4a4ddf8eb2b1cc7039e8a66a23a424961af.zip
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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>
Diffstat (limited to 'fs/xfs/xfs_error.h')
-rw-r--r--fs/xfs/xfs_error.h18
1 files changed, 6 insertions, 12 deletions
diff --git a/fs/xfs/xfs_error.h b/fs/xfs/xfs_error.h
index f338847..10dce54 100644
--- a/fs/xfs/xfs_error.h
+++ b/fs/xfs/xfs_error.h
@@ -136,8 +136,8 @@ extern int xfs_error_test(int, int *, char *, int, char *, unsigned long);
xfs_error_test((tag), (mp)->m_fixedfsid, "expr", __LINE__, __FILE__, \
(rf))))
-extern int xfs_errortag_add(int error_tag, xfs_mount_t *mp);
-extern int xfs_errortag_clearall(xfs_mount_t *mp, int loud);
+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)
@@ -162,21 +162,15 @@ extern int xfs_errortag_clearall(xfs_mount_t *mp, int loud);
struct xfs_mount;
-extern void xfs_fs_vcmn_err(int level, struct xfs_mount *mp,
- char *fmt, va_list ap)
- __attribute__ ((format (printf, 3, 0)));
-extern void xfs_cmn_err(int panic_tag, int level, struct xfs_mount *mp,
- char *fmt, ...)
- __attribute__ ((format (printf, 4, 5)));
-extern void xfs_fs_cmn_err(int level, struct xfs_mount *mp, char *fmt, ...)
- __attribute__ ((format (printf, 3, 4)));
-
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...) \
- ((f & XFS_MFSI_QUIET)? (void)0 : cmn_err(CE_WARN, "XFS: " 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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