Re: [PATCH] target: simplify target_parse_naa_6h_vendor_specific()

["Nicholas A. Bellinger" <nab@xxxxxxxxxxxxxxx>]

On Wed, 2011-09-28 at 14:04 -0700, Nicholas A. Bellinger wrote:
> On Tue, 2011-09-27 at 13:48 +0300, Andy Shevchenko wrote:
> > On Mon, Sep 19, 2011 at 11:11 AM, Andy Shevchenko
> > <andriy.shevchenko@xxxxxxxxxxxxxxx> wrote:
> > > Signed-off-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
> > > Cc: Nicholas Bellinger <nab@xxxxxxxxxxxxxxx>
> > > ---
> > >  drivers/target/target_core_cdb.c |   30 +++++++++++++-----------------
> > >  1 files changed, 13 insertions(+), 17 deletions(-)
> > >
> > > diff --git a/drivers/target/target_core_cdb.c b/drivers/target/target_core_cdb.c
> > > index f04d4ef..b796115 100644
> > > --- a/drivers/target/target_core_cdb.c
> > > +++ b/drivers/target/target_core_cdb.c
> > > @@ -24,7 +24,6 @@
> > >  */
> > >
> > >  #include <linux/kernel.h>
> > > -#include <linux/ctype.h>
> > >  #include <asm/unaligned.h>
> > >  #include <scsi/scsi.h>
> > >
> > > @@ -156,11 +155,12 @@ target_emulate_evpd_80(struct se_cmd *cmd, unsigned char *buf)
> > >  }
> > >
> > >  static void
> > > -target_parse_naa_6h_vendor_specific(struct se_device *dev, unsigned char *buf_off)
> > > +target_parse_naa_6h_vendor_specific(struct se_device *dev, unsigned char *buf)
> > >  {
> > >        unsigned char *p = &dev->se_sub_dev->t10_wwn.unit_serial[0];
> > > -       unsigned char *buf = buf_off;
> > > -       int cnt = 0, next = 1;
> > > +       int cnt;
> > > +       bool next = true;
> > > +
> > >        /*
> > >         * Generate up to 36 bits of VENDOR SPECIFIC IDENTIFIER starting on
> > >         * byte 3 bit 3-0 for NAA IEEE Registered Extended DESIGNATOR field
> > > @@ -169,20 +169,16 @@ target_parse_naa_6h_vendor_specific(struct se_device *dev, unsigned char *buf_of
> > >         * NUMBER set via vpd_unit_serial in target_core_configfs.c to ensure
> > >         * per device uniqeness.
> > >         */
> > > -       while (*p != '\0') {
> > > -               if (cnt >= 13)
> > > -                       break;
> > > -               if (!isxdigit(*p)) {
> > > -                       p++;
> > > +       for (cnt = 0; *p && cnt < 13; next = !next) {
> > > +               int val = hex_to_bin(*p++);
> > > +
> > > +               if (val < 0)
> > >                        continue;
> > > -               }
> > > -               if (next != 0) {
> > > -                       buf[cnt++] |= hex_to_bin(*p++);
> > > -                       next = 0;
> > > -               } else {
> > > -                       buf[cnt] = hex_to_bin(*p++) << 4;
> > > -                       next = 1;
> > > -               }
> > > +
> > > +               if (next)
> > > +                       buf[cnt++] |= val;
> > > +               else
> > > +                       buf[cnt] = val << 4;
> > >        }
> > >  }
> > >
> > 
> > Nicholas, any comment on this?
> > 
> 
> Hi Andy,
> 
> This simplification is fine with me, and will plan to queue this for
> v3.2.
> 

Hi Andy,

So I finally got around to testing this patch, but unfortunately it does
not produce the same results as the original code.  The problem is due
to the 'next = !next' assignment in the above for loop, which causes the
value to be reset even when hex_to_bin() detects an non hex character..

Here is an updated patch that I will be commiting into lio-core-2.6.git.

Thanks,

--nab


diff --git a/drivers/target/target_core_cdb.c b/drivers/target/target_core_cdb.c
index f04d4ef..0d02391 100644
--- a/drivers/target/target_core_cdb.c
+++ b/drivers/target/target_core_cdb.c
@@ -24,7 +24,6 @@
  */
 
 #include <linux/kernel.h>
-#include <linux/ctype.h>
 #include <asm/unaligned.h>
 #include <scsi/scsi.h>
 
@@ -156,11 +155,12 @@ target_emulate_evpd_80(struct se_cmd *cmd, unsigned char *buf)
 }
 
 static void
-target_parse_naa_6h_vendor_specific(struct se_device *dev, unsigned char *buf_off)
+target_parse_naa_6h_vendor_specific(struct se_device *dev, unsigned char *buf)
 {
        unsigned char *p = &dev->se_sub_dev->t10_wwn.unit_serial[0];
-       unsigned char *buf = buf_off;
-       int cnt = 0, next = 1;
+       int cnt;
+       bool next = true;
+
        /*
         * Generate up to 36 bits of VENDOR SPECIFIC IDENTIFIER starting on
         * byte 3 bit 3-0 for NAA IEEE Registered Extended DESIGNATOR field
@@ -169,19 +169,18 @@ target_parse_naa_6h_vendor_specific(struct se_device *dev, unsigned char *buf_of
         * NUMBER set via vpd_unit_serial in target_core_configfs.c to ensure
         * per device uniqeness.
         */
-       while (*p != '\0') {
-               if (cnt >= 13)
-                       break;
-               if (!isxdigit(*p)) {
-                       p++;
+       for (cnt = 0; *p && cnt < 13; p++) {
+               int val = hex_to_bin(*p);
+
+               if (val < 0)
                        continue;
-               }
-               if (next != 0) {
-                       buf[cnt++] |= hex_to_bin(*p++);
-                       next = 0;
+
+               if (next) {
+                       next = false;
+                       buf[cnt++] |= val;
                } else {
-                       buf[cnt] = hex_to_bin(*p++) << 4;
-                       next = 1;
+                       next = true;
+                       buf[cnt] = val << 4;
                }
        }
 }


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