[PATCH] scsi: sd: Make protection lookup tables static

[PATCH] scsi: sd: Make protection lookup tables static

[John Garry]

Currently the protection lookup tables in sd_prot_flag_mask() and
sd_prot_op() are declared non-static. As such, they will be rebuilt for
each respective function call.

Optimise by making them static.

This saves ~100B object code for sd.c:

Before:
   text	   data	    bss	    dec	    hex	filename
  25403	   1024	     16	  26443	   674b	drivers/scsi/sd.o

After:
  text	   data	    bss	    dec	    hex	filename
  25299	   1024	     16	  26339	   66e3	drivers/scsi/sd.o

Signed-off-by: John Garry <john.garry@huawei.com>

diff --git a/drivers/scsi/sd.h b/drivers/scsi/sd.h
index 1d63f3a..89e6d42 100644
--- a/drivers/scsi/sd.h
+++ b/drivers/scsi/sd.h
@@ -195,15 +195,15 @@ static inline sector_t sectors_to_logical(struct scsi_device *sdev, sector_t sec
 static inline unsigned int sd_prot_op(bool write, bool dix, bool dif)
 {
 	/* Lookup table: bit 2 (write), bit 1 (dix), bit 0 (dif) */
-	const unsigned int ops[] = {	/* wrt dix dif */
-		SCSI_PROT_NORMAL,	/*  0	0   0  */
-		SCSI_PROT_READ_STRIP,	/*  0	0   1  */
-		SCSI_PROT_READ_INSERT,	/*  0	1   0  */
-		SCSI_PROT_READ_PASS,	/*  0	1   1  */
-		SCSI_PROT_NORMAL,	/*  1	0   0  */
-		SCSI_PROT_WRITE_INSERT, /*  1	0   1  */
-		SCSI_PROT_WRITE_STRIP,	/*  1	1   0  */
-		SCSI_PROT_WRITE_PASS,	/*  1	1   1  */
+	static const unsigned int ops[] = {	/* wrt dix dif */
+		SCSI_PROT_NORMAL,		/*  0	0   0  */
+		SCSI_PROT_READ_STRIP,		/*  0	0   1  */
+		SCSI_PROT_READ_INSERT,		/*  0	1   0  */
+		SCSI_PROT_READ_PASS,		/*  0	1   1  */
+		SCSI_PROT_NORMAL,		/*  1	0   0  */
+		SCSI_PROT_WRITE_INSERT,		/*  1	0   1  */
+		SCSI_PROT_WRITE_STRIP,		/*  1	1   0  */
+		SCSI_PROT_WRITE_PASS,		/*  1	1   1  */
 	};
 
 	return ops[write << 2 | dix << 1 | dif];
@@ -215,7 +215,7 @@ static inline unsigned int sd_prot_op(bool write, bool dix, bool dif)
  */
 static inline unsigned int sd_prot_flag_mask(unsigned int prot_op)
 {
-	const unsigned int flag_mask[] = {
+	static const unsigned int flag_mask[] = {
 		[SCSI_PROT_NORMAL]		= 0,
 
 		[SCSI_PROT_READ_STRIP]		= SCSI_PROT_TRANSFER_PI |
-- 
1.9.1

Re: [PATCH] scsi: sd: Make protection lookup tables static

[Bart Van Assche]

On Mon, 2019-01-07 at 22:41 +0800, John Garry wrote:
> Currently the protection lookup tables in sd_prot_flag_mask() and
> sd_prot_op() are declared non-static. As such, they will be rebuilt for
> each respective function call.
> 
> Optimise by making them static.
> 
> This saves ~100B object code for sd.c:
> 
> Before:
>    text	   data	    bss	    dec	    hex	filename
>   25403	   1024	     16	  26443	   674b	drivers/scsi/sd.o
> 
> After:
>   text	   data	    bss	    dec	    hex	filename
>   25299	   1024	     16	  26339	   66e3	drivers/scsi/sd.o

Since the sd_prot_op() function only has a single caller, please move it from sd.h
into sd.c.

Thanks,

Bart.

Re: [PATCH] scsi: sd: Make protection lookup tables static

[John Garry]

On 07/01/2019 16:57, Bart Van Assche wrote:
> On Mon, 2019-01-07 at 22:41 +0800, John Garry wrote:
>> Currently the protection lookup tables in sd_prot_flag_mask() and
>> sd_prot_op() are declared non-static. As such, they will be rebuilt for
>> each respective function call.
>>
>> Optimise by making them static.
>>
>> This saves ~100B object code for sd.c:
>>
>> Before:
>>    text	   data	    bss	    dec	    hex	filename
>>   25403	   1024	     16	  26443	   674b	drivers/scsi/sd.o
>>
>> After:
>>   text	   data	    bss	    dec	    hex	filename
>>   25299	   1024	     16	  26339	   66e3	drivers/scsi/sd.o
>
> Since the sd_prot_op() function only has a single caller, please move it from sd.h
> into sd.c.

Can do, as long as no one has objection.

Function sd_prot_flag_mask() also has a single caller AFAICS, so this 
could also be relocated.

Cheers,
John

>
> Thanks,
>
> Bart.
>
>

Re: [PATCH] scsi: sd: Make protection lookup tables static

[Bart Van Assche]

On Mon, 2019-01-07 at 17:27 +0000, John Garry wrote:
> On 07/01/2019 16:57, Bart Van Assche wrote:
> > On Mon, 2019-01-07 at 22:41 +0800, John Garry wrote:
> > > Currently the protection lookup tables in sd_prot_flag_mask() and
> > > sd_prot_op() are declared non-static. As such, they will be rebuilt for
> > > each respective function call.
> > > 
> > > Optimise by making them static.
> > > 
> > > This saves ~100B object code for sd.c:
> > > 
> > > Before:
> > >    text	   data	    bss	    dec	    hex	filename
> > >   25403	   1024	     16	  26443	   674b	drivers/scsi/sd.o
> > > 
> > > After:
> > >   text	   data	    bss	    dec	    hex	filename
> > >   25299	   1024	     16	  26339	   66e3	drivers/scsi/sd.o
> > 
> > Since the sd_prot_op() function only has a single caller, please move it from sd.h
> > into sd.c.
> 
> Can do, as long as no one has objection.
> 
> Function sd_prot_flag_mask() also has a single caller AFAICS, so this 
> could also be relocated.

Please move that function too from sd.h into sd.c.

Thanks,

Bart.