Messages in this thread | | | Date | Sun, 30 Oct 2005 22:48:20 -0500 | From | Jeff Garzik <> | Subject | Re: [PATCH] ide-scsi highmem cleanup |
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Linux Kernel Mailing List wrote: > tree c6016a8741a2527acac0ceb6e6ce431a798d6708 > parent f1fc78a8c7f3a784b9fd1e07cc1438a0ea569555 > author Andrew Morton <akpm@osdl.org> Mon, 31 Oct 2005 07:00:13 -0800 > committer Linus Torvalds <torvalds@g5.osdl.org> Mon, 31 Oct 2005 09:37:17 -0800 > > [PATCH] ide-scsi highmem cleanup > > It's not necessary to test PageHighmem in here - kmap_atomic() does the right > thing. > > Cc: Bartlomiej Zolnierkiewicz <B.Zolnierkiewicz@elka.pw.edu.pl> > Signed-off-by: Andrew Morton <akpm@osdl.org> > Signed-off-by: Linus Torvalds <torvalds@osdl.org> > > drivers/scsi/ide-scsi.c | 38 ++++++++++++-------------------------- > 1 files changed, 12 insertions(+), 26 deletions(-) > > diff --git a/drivers/scsi/ide-scsi.c b/drivers/scsi/ide-scsi.c > --- a/drivers/scsi/ide-scsi.c > +++ b/drivers/scsi/ide-scsi.c > @@ -180,19 +180,12 @@ static void idescsi_input_buffers (ide_d > return; > } > count = min(pc->sg->length - pc->b_count, bcount); > - if (PageHighMem(pc->sg->page)) { > - unsigned long flags; > - > - local_irq_save(flags); > - buf = kmap_atomic(pc->sg->page, KM_IRQ0) + pc->sg->offset; > - drive->hwif->atapi_input_bytes(drive, buf + pc->b_count, count); > - kunmap_atomic(buf - pc->sg->offset, KM_IRQ0); > - local_irq_restore(flags); > - } else { > - buf = page_address(pc->sg->page) + pc->sg->offset; > - drive->hwif->atapi_input_bytes(drive, buf + pc->b_count, count); > - } > - bcount -= count; pc->b_count += count; > + buf = kmap_atomic(pc->sg->page, KM_IRQ0); > + drive->hwif->atapi_input_bytes(drive, > + buf + pc->b_count + pc->sg->offset, count); > + kunmap_atomic(buf, KM_IRQ0); > + bcount -= count; > + pc->b_count += count; > if (pc->b_count == pc->sg->length) { > pc->sg++; > pc->b_count = 0; > @@ -212,19 +205,12 @@ static void idescsi_output_buffers (ide_ > return; > } > count = min(pc->sg->length - pc->b_count, bcount); > - if (PageHighMem(pc->sg->page)) { > - unsigned long flags; > - > - local_irq_save(flags); > - buf = kmap_atomic(pc->sg->page, KM_IRQ0) + pc->sg->offset; > - drive->hwif->atapi_output_bytes(drive, buf + pc->b_count, count); > - kunmap_atomic(buf - pc->sg->offset, KM_IRQ0); > - local_irq_restore(flags); > - } else { > - buf = page_address(pc->sg->page) + pc->sg->offset; > - drive->hwif->atapi_output_bytes(drive, buf + pc->b_count, count); > - } > - bcount -= count; pc->b_count += count; > + buf = kmap_atomic(pc->sg->page, KM_IRQ0); > + drive->hwif->atapi_output_bytes(drive, > + buf + pc->b_count + pc->sg->offset, count); > + kunmap_atomic(buf, KM_IRQ0); > + bcount -= count; > + pc->b_count += count;
Unless I'm missing something, this patch looks very wrong.
kmap_atomic(..., KM_IRQx) needs to be inside local_irq_save().
As such, the PageHighMem() does have clear benefits.
Jeff
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