Geert,
thanks for passing that on - I had in fact disabled that feature of the
driver for a good part of the 3.x series of kernels while attempting to
figure out what else is wrong with the locking scheme.
I'll take a fresh stab at this.
Cheers,
Michael
Am 03.01.2014 um 01:26 schrieb Geert Uytterhoeven:
---------- Forwarded message ----------
From: Arnd Bergmann <arnd@xxxxxxxx>
Date: Thu, Jan 2, 2014 at 1:07 PM
Subject: [PATCH, RFC 02/30] scsi: atari_scsi: fix sleep_on race
To: linux-kernel@xxxxxxxxxxxxxxx
Cc: Arnd Bergmann <arnd@xxxxxxxx>, Geert Uytterhoeven
<geert@xxxxxxxxxxxxxx>, "James E.J. Bottomley"
<JBottomley@xxxxxxxxxxxxx>, linux-scsi@xxxxxxxxxxxxxxx
sleep_on is known broken and going away. The atari_scsi driver is one
of
two remaining users in the falcon_get_lock() function, which is a
rather
crazy piece of code. This does not attempt to fix the driver's locking
scheme in general, but at least prevents falcon_get_lock from going to
sleep when no other thread holds the same lock or tries to get it,
and we no longer schedule with irqs disabled.
Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
Cc: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>
Cc: James E.J. Bottomley <JBottomley@xxxxxxxxxxxxx>
Cc: linux-scsi@xxxxxxxxxxxxxxx
---
drivers/scsi/atari_scsi.c | 12 +++++++++---
1 file changed, 9 insertions(+), 3 deletions(-)
diff --git a/drivers/scsi/atari_scsi.c b/drivers/scsi/atari_scsi.c
index a3e6c8a..b55a58a 100644
--- a/drivers/scsi/atari_scsi.c
+++ b/drivers/scsi/atari_scsi.c
@@ -90,6 +90,7 @@
#include <linux/init.h>
#include <linux/nvram.h>
#include <linux/bitops.h>
+#include <linux/wait.h>
#include <asm/setup.h>
#include <asm/atarihw.h>
@@ -549,8 +550,10 @@ static void falcon_get_lock(void)
local_irq_save(flags);
- while (!in_irq() && falcon_got_lock && stdma_others_waiting())
- sleep_on(&falcon_fairness_wait);
+ wait_event_cmd(falcon_fairness_wait,
+ !in_irq() && falcon_got_lock &&
stdma_others_waiting(),
+ local_irq_restore(flags),
+ local_irq_save(flags));
while (!falcon_got_lock) {
if (in_irq())
@@ -562,7 +565,10 @@ static void falcon_get_lock(void)
falcon_trying_lock = 0;
wake_up(&falcon_try_wait);
} else {
- sleep_on(&falcon_try_wait);
+ wait_event_cmd(falcon_try_wait,
+ !falcon_got_lock &&
!falcon_trying_lock,
+ local_irq_restore(flags),
+ local_irq_save(flags));
}
}
--
1.8.3.2
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