---------- Forwarded message ----------
From: Jiri Kosina <jkosina@xxxxxxx>
Date: Fri, 9 Oct 2009 11:53:21 +0200 (CEST)
Subject: [PATCH] [RFC] ataflop: remove buggy IRQ disable from do_fd_request()
To: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>, Tejun Heo
<tj@xxxxxxxxxx>, Jens Axboe <jens.axboe@xxxxxxxxxx>
Cc: linux-kernel@xxxxxxxxxxxxxxx
There is a nice gem in drivers/block/ataflop.c::do_fd_request()
void do_fd_request(struct request_queue * q)
{
unsigned long flags;
DPRINT(("do_fd_request for pid %d\n",current->pid));
while( fdc_busy ) sleep_on( &fdc_wait );
fdc_busy = 1;
stdma_lock(floppy_irq, NULL);
atari_disable_irq( IRQ_MFP_FDC );
local_save_flags(flags); /* The request function is called with ints
local_irq_disable(); * disabled... so must save the IPL
for later */
redo_fd_request();
local_irq_restore(flags);
atari_enable_irq( IRQ_MFP_FDC );
}
If you look at the code long enough, you will notioce that the
local_irq_disable() call is actually commented out. This has been
introduced back in 2002 in [1], but as you can see, the same bug has been
there even before, with the sti() call being commented out in the very
same way :)
I am not familiar with the code myself at all, but I guess that the whole
stuff can just be removed. Why do we need save_flags/restore_flags at all,
without actually disabling the local IRQs afterwards? The
redo_fd_request() doesn't seem to do anything that would mess with flags
inconsistently.
But I'd rather anyone who has touched the surrounding code in past years
Ack it. I can then take it through trivial tree or submit to akpm.
[1] http://lkml.org/lkml/2002/12/27/58
Signed-off-by: Jiri Kosina <jkosina@xxxxxxx>
---
drivers/block/ataflop.c | 3 ---
1 files changed, 0 insertions(+), 3 deletions(-)
diff --git a/drivers/block/ataflop.c b/drivers/block/ataflop.c
index 847a9e5..a5af1d6 100644
--- a/drivers/block/ataflop.c
+++ b/drivers/block/ataflop.c
@@ -1478,10 +1478,7 @@ void do_fd_request(struct request_queue * q)
stdma_lock(floppy_irq, NULL);
atari_disable_irq( IRQ_MFP_FDC );
- local_save_flags(flags); /* The request function is called with ints
- local_irq_disable(); * disabled... so must save the IPL for later */
redo_fd_request();
- local_irq_restore(flags);
atari_enable_irq( IRQ_MFP_FDC );
}
--
1.5.6
--
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
--
To unsubscribe from this list: send the line "unsubscribe linux-m68k" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
