avoid memory allocations in xfs_fs_vcmn_err

Do we really want to drop the whole message if the fs name can't fit? Maybe drop the fsname altogether and print the error anyway? Being completely silent doesn't sound great...

xfs_fs_vcmn_err can be called under a spinlock, but does a sleeping memory allocation to create buffer for it's internal sprintf. Fortunately it's the only caller of icmn_err, so we can merge the two and have one single static buffer and spinlock protecting it. While we're at it make sure we proper __attribute__ format annotations so that the compiler can detect mismatched format strings.

Reported-by Alexander Beregalov <[email protected]>

Signed-off-by Christoph Hellwig <[email protected]>

Index: xfs/fs/xfs/support/debug.c
===================================================================

fs/xfs/support/debug.c +32 -5

@@ -18,6 +18,13 @@
 #include <xfs.h>
 #include "debug.h"
 
+/* xfs_mount.h drags a lot of crap in, sorry.. */
+#include "xfs_sb.h"
+#include "xfs_inum.h"
+#include "xfs_ag.h"
+#include "xfs_dmapi.h"
+#include "xfs_mount.h"
+
 static char		message[1024];	/* keep it off the stack */
 static DEFINE_SPINLOCK(xfs_err_lock);
 

@@ -55,22 +62,42 @@ cmn_err(register int level, char *fmt, .
 }
 
 void
-icmn_err(register int level, char *fmt, va_list ap)
+xfs_fs_vcmn_err(
+	int			level,
+	struct xfs_mount	*mp,
+	char			*fmt,
+	va_list			ap)
 {
-	ulong	flags;
-	int	len;
+	unsigned long		flags;
+	int			len = 0;
 
 	level &= XFS_ERR_MASK;
-	if(level > XFS_MAX_ERR_LEVEL)
+	if (level > XFS_MAX_ERR_LEVEL)
 		level = XFS_MAX_ERR_LEVEL;
+
 	spin_lock_irqsave(&xfs_err_lock,flags);
-	len = vsnprintf(message, sizeof(message), fmt, ap);
+
+	if (mp) {
+		len = sprintf(message, "Filesystem \"%s\": ", mp->m_fsname);
+
+		/*
+		 * Skip the printk if we can't print anything useful
+		 * due to an over-long device name.
+		 */
+		if (len >= sizeof(message))
+			goto out;
+	}
+
+	len = vsnprintf(message + len, sizeof(message) - len, fmt, ap);
 	if (len >= sizeof(message))
 		len = sizeof(message) - 1;
 	if (message[len-1] == '\n')
 		message[len-1] = 0;
+
 	printk("%s%s\n", err_level[level], message);
+ out:
 	spin_unlock_irqrestore(&xfs_err_lock,flags);
+
 	BUG_ON(level == CE_PANIC);
 }
 

Index: xfs/fs/xfs/support/debug.h
===================================================================

fs/xfs/support/debug.h +0 -2

@@ -27,8 +27,6 @@
 #define CE_ALERT        1               /* alert        */
 #define CE_PANIC        0               /* panic        */
 
-extern void icmn_err(int, char *, va_list)
-	__attribute__ ((format (printf, 2, 0)));
 extern void cmn_err(int, char *, ...)
 	__attribute__ ((format (printf, 2, 3)));
 extern void assfail(char *expr, char *f, int l);

Index: xfs/fs/xfs/xfs_error.c
===================================================================

fs/xfs/xfs_error.c +0 -15

@@ -153,21 +153,6 @@ xfs_errortag_clearall(xfs_mount_t *mp, i
 }
 #endif /* DEBUG */
 
-static void
-xfs_fs_vcmn_err(int level, xfs_mount_t *mp, char *fmt, va_list ap)
-{
-	if (mp != NULL) {
-		char	*newfmt;
-		int	len = 16 + mp->m_fsname_len + strlen(fmt);
-
-		newfmt = kmem_alloc(len, KM_SLEEP);
-		sprintf(newfmt, "Filesystem \"%s\": %s", mp->m_fsname, fmt);
-		icmn_err(level, newfmt, ap);
-		kmem_free(newfmt);
-	} else {
-		icmn_err(level, fmt, ap);
-	}
-}
 
 void
 xfs_fs_cmn_err(int level, xfs_mount_t *mp, char *fmt, ...)

Index: xfs/fs/xfs/xfs_error.h
===================================================================

fs/xfs/xfs_error.h +8 -4

@@ -159,11 +159,15 @@ extern int xfs_errortag_clearall(xfs_mou
 #define		XFS_PTAG_FSBLOCK_ZERO		0x00000080
 
 struct xfs_mount;
-/* PRINTFLIKE4 */
+
+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, ...);
-/* PRINTFLIKE3 */
-extern void xfs_fs_cmn_err(int level, struct xfs_mount *mp, char *fmt, ...);
+			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);
 

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