Re: [PATCH 2.6.11-rc2 04/09] ide: convert REQ_DRIVE_TASK to REQ_DRIVE_TASKFILE

[Tejun Heo]

Bartlomiej Zolnierkiewicz wrote:
> I put some more thought into this change... details below...
>
> On Sat,  5 Feb 2005 11:15:56 +0900 (KST), Tejun Heo <tj@xxxxxxxxxxx> wrote:
>
>
> > @@ -705,24 +705,17 @@ static int idedisk_issue_flush(request_q
> > {
> >        ide_drive_t *drive = q->queuedata;
> >        struct request *rq;
> > +       ide_task_t args;
> >        int ret;
>
>
> ide_task_t task please

 Okay.

> > @@ -730,8 +723,9 @@ static int idedisk_issue_flush(request_q
> >         * if we failed and caller wants error offset, get it
> >         */
> >        if (ret && error_sector)
> > -               *error_sector = ide_get_error_location(drive, rq->cmd);
> > +               *error_sector = ide_get_error_location(drive, &args);
> >
> > +       rq->special = NULL;     /* just in case */
>
>
> In what case?

 As the request is allocated and freed by the generic block layer, I 
was kinda worrying about cases where the request outlives 
blk_put_request() and somehow somebody accesses ->special.  Probably 
unnecessary but dangling pointers pointing stack area really scares me.

> > @@ -55,22 +55,19 @@
> > #include <asm/io.h>
> > #include <asm/bitops.h>
> >
> > -static void ide_fill_flush_cmd(ide_drive_t *drive, struct request *rq)
> > +void ide_init_flush_task(ide_drive_t *drive, ide_task_t *args)
>
>
> ide_task_t *task
>
>
> > @@ -80,7 +77,9 @@ static void ide_fill_flush_cmd(ide_drive
> > static struct request *ide_queue_flush_cmd(ide_drive_t *drive,
> >                                           struct request *rq, int post)
> > {
> > -       struct request *flush_rq = &HWGROUP(drive)->wrq;
> > +       ide_hwgroup_t *hwgroup = drive->hwif->hwgroup;
> > +       struct request *flush_rq = &hwgroup->flush_rq;
> > +       ide_task_t *args = &hwgroup->flush_args;
>
>
> ide_task_t *task
>
>
> > @@ -221,41 +223,37 @@ static void ide_complete_pm_request (ide
> > /*
> >  * FIXME: probably move this somewhere else, name is bad too :)
> >  */
> > -u64 ide_get_error_location(ide_drive_t *drive, char *args)
> > +u64 ide_get_error_location(ide_drive_t *drive, ide_task_t *args)
>
>
> ide_task_t *task
>
>
> > {
> >        u32 high, low;
> >        u8 hcyl, lcyl, sect;
> > -       u64 sector;
> >
> > -       high = 0;
> > -       hcyl = args[5];
> > -       lcyl = args[4];
> > -       sect = args[3];
> > -
> > -       if (ide_id_has_flush_cache_ext(drive->id)) {
> > -               low = (hcyl << 16) | (lcyl << 8) | sect;
> > -               HWIF(drive)->OUTB(drive->ctl|0x80, IDE_CONTROL_REG);
> > -               high = ide_read_24(drive);
> > -       } else {
> > -               u8 cur = HWIF(drive)->INB(IDE_SELECT_REG);
> > -               if (cur & 0x40)
> > -                       low = (hcyl << 16) | (lcyl << 8) | sect;
> > -               else {
> > -                       low = hcyl * drive->head * drive->sect;
> > -                       low += lcyl * drive->sect;
> > -                       low += sect - 1;
> > -               }
> > -       }
> > +       if (ide_id_has_flush_cache_ext(drive->id) &&
> > +           (drive->capacity64 >= (1UL << 28)))
>
>
> Please just use if (drive->addressing), it is simpler and still correct.
> Since we are now using ide_task_t 'high' will be 0 when
> ide_id_has_flush_cache() == 0 and drive->addressing == 1
> (such combination is unlikely but...).  Also thanks to this change
> ide_get_error_location() becomes a really *generic* helper and
> can be later used by other code.

 Sure.

> > @@ -1201,9 +1224,14 @@ extern ide_startstop_t ide_do_reset (ide
> > extern void ide_init_drive_cmd (struct request *rq);
> >
> > /*
> > + * This function initializes @task to WIN_FLUSH_CACHE[_EXT] command.
> > + */
> > +void ide_init_flush_task(ide_drive_t *drive, ide_task_t *args);
>
>
> comment is wrong and not needed,
>
> void ide_init_flush_task(ide_drive_t *, ide_task_t *);
>
> should be enough

 Okay.

> There is one problem left with this change - FLUSH_CACHE_{EXT}
> command handling becomes slower for drive's supporting LBA48
> (also next patches make ide_{task,cmd}_ioctl() slower).  Why is so?
> See do_rw_taskfile(), HOB registers are written/read unconditionally
> if (drive->addressing == 1).  This can be fixed by i.e. adding
> 'unsigned long flags' to ide_task_t and IDE_TASK_LBA48 flag.
> BTW this fix is needed also to implement LBA48 optimization for
> read/write requests (not writing HOB registers when not needed).
>
> IMHO there are some things worth mentioning in the patch description,
> do_rw_taskfile() vs execute_drive_cmd()+ide_cmd() details:
> some registers are written now in different order and timeout is bumped
> (these changes shouldn't make any harm but I'm paranoid :).

 Yeah, sure.

 Thanks.

--
tejun

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