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
$ diff -u drivers/scsi/ultrastor.s{_,}
--- drivers/scsi/ultrastor.s_ 2008-01-16 16:40:01.000000000 +0100
+++ drivers/scsi/ultrastor.s 2008-01-16 16:40:19.000000000 +0100
@@ -1457,7 +1457,7 @@
je .L268 #,
#APP
xorl %ebp,%ebp # mscp_index
-0: bsfw config+20,%bp # config.mscp_free, mscp_index
+ 0: bsfw config+20,%bp # config.mscp_free, mscp_index
btr %ebp,config+20 # mscp_index, config.mscp_free
jnc 0b
#NO_APP
@@ -1726,9 +1726,9 @@
call panic #
.size ultrastor_queuecommand, .-ultrastor_queuecommand
.section .modinfo,"a",@progbits
- .type __mod_license1184, @object
- .size __mod_license1184, 12
-__mod_license1184:
+ .type __mod_license1191, @object
+ .size __mod_license1191, 12
+__mod_license1191:
.string "license=GPL"
.section .rodata.str1.1
.LC27:
Regards,
Frederik
Signed-off-by: Frederik Deweerdt <[email protected]>
diff --git a/drivers/scsi/ultrastor.c b/drivers/scsi/ultrastor.c
index 6d1f0ed..93c5a67 100644
--- a/drivers/scsi/ultrastor.c
+++ b/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;
}