swim3: fix interruptible_sleep_on race

interruptible_sleep_on is racy and going away. This replaces the one
caller in the swim3 driver with the equivalent race-free
wait_event_interruptible call. Since we're here already, this
also fixes the case where we get interrupted from atomic context,
which used to just spin in the loop.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Jens Axboe <axboe@fb.com>

1 files changed, 11 insertions, 7 deletions

diff --git a/drivers/block/swim3.c b/drivers/block/swim3.c
index 20e061c3e023..c74f7b56e7c4 100644
--- a/drivers/block/swim3.c
+++ b/drivers/block/swim3.c
@@ -30,6 +30,7 @@
 #include <linux/mutex.h>
 #include <linux/module.h>
 #include <linux/spinlock.h>
+#include <linux/wait.h>
 #include <asm/io.h>
 #include <asm/dbdma.h>
 #include <asm/prom.h>
@@ -840,14 +841,17 @@ static int grab_drive(struct floppy_state *fs, enum swim_state state,
         spin_lock_irqsave(&swim3_lock, flags);
         if (fs->state != idle && fs->state != available) {
                 ++fs->wanted;
-                while (fs->state != available) {
+                /* this will enable irqs in order to sleep */
+                if (!interruptible)
+                        wait_event_lock_irq(fs->wait,
+                                        fs->state == available,
+                                        swim3_lock);
+                else if (wait_event_interruptible_lock_irq(fs->wait,
+                                        fs->state == available,
+                                        swim3_lock)) {
+                        --fs->wanted;
                         spin_unlock_irqrestore(&swim3_lock, flags);
-                        if (interruptible && signal_pending(current)) {
-                                --fs->wanted;
-                                return -EINTR;
-                        }
-                        interruptible_sleep_on(&fs->wait);
-                        spin_lock_irqsave(&swim3_lock, flags);
+                        return -EINTR;
                 }
                 --fs->wanted;
         }