[SCSI] ultrastor: clean up inline asm warnings

To: [email protected]
Cc: [email protected]
Subject: [trivial patch] scsi/ultrastor: clean up inline asm warnings

Hi,

Compiling latest mainline with gcc 4.2.1 spews the following warnings:

drivers/scsi/ultrastor.c: In function 'find_and_clear_bit_16':
drivers/scsi/ultrastor.c:303: warning: matching constraint does not allow a register
drivers/scsi/ultrastor.c:302: warning: matching constraint does not allow a register
drivers/scsi/ultrastor.c: At top level:
drivers/scsi/ultrastor.c:1202: warning: matching constraint does not allow a register
drivers/scsi/ultrastor.c:1202: warning: matching constraint does not allow a register
drivers/scsi/ultrastor.c: In function 'ultrastor_queuecommand':
drivers/scsi/ultrastor.c:698: warning: matching constraint does not allow a register
drivers/scsi/ultrastor.c:698: warning: matching constraint does not allow a register
drivers/scsi/ultrastor.c:698: warning: matching constraint does not allow a register
drivers/scsi/ultrastor.c:698: warning: matching constraint does not allow a register
drivers/scsi/ultrastor.c:698: warning: matching constraint does not allow a register
drivers/scsi/ultrastor.c:698: warning: matching constraint does not allow a register
drivers/scsi/ultrastor.c:698: warning: matching constraint does not allow a register
drivers/scsi/ultrastor.c:302: warning: matching constraint does not allow a register
drivers/scsi/ultrastor.c:302: warning: matching constraint does not allow a register

The following patch fixes it by using the '+' operator on the (*field)
operand, marking it as read-write to gcc. I diffed the two resulting .s,
and gcc produced the same code. This was tested with gcc 4.2.1 and gcc 3.4.3

Signed-off-by: Frederik Deweerdt <[email protected]>
Cc: Adrian Bunk <[email protected]>
Signed-off-by: James Bottomley <[email protected]>

Author: Frederik Deweerdt

drivers/scsi/ultrastor.c

@@ -298,9 +298,16 @@ static inline int find_and_clear_bit_16(unsigned long *field)
 {
   int rv;
 
-  if (*field == 0) panic("No free mscp");
-  asm("xorl %0,%0\n0:\tbsfw %1,%w0\n\tbtr %0,%1\n\tjnc 0b"
-      : "=&r" (rv), "=m" (*field) : "1" (*field));
+  if (*field == 0)
+    panic("No free mscp");
+
+  asm volatile (
+	"xorl %0,%0\n\t"
+	"0: bsfw %1,%w0\n\t"
+	"btr %0,%1\n\t"
+	"jnc 0b"
+	: "=&r" (rv), "=m" (*field) :);
+
   return rv;
 }