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[SCSI] atari_scsi: Fix sleep_on race 

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@arndb.de>
[MSch: fixed completion conditions missed in Arnds' original RFC patch]
Signed-off-by: Michael Schmitz <schmitz@debian.org>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: James E.J. Bottomley <JBottomley@parallels.com>
Cc: linux-scsi@vger.kernel.org
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
hifive-unleashed-5.1
Arnd Bergmann 2014-03-01 20:51:03 +13:00 committed by Geert Uytterhoeven
parent ecc79d4964
commit eff9cf8d6e
1 changed files with 9 additions and 3 deletions
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12
drivers/scsi/atari_scsi.c
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@ -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_interrupt() || !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));
}
}