mtd: fix race in cfi_cmdset_0001 driver

As inval_cache_and_wait_for_operation() drop and reclaim the lock
to invalidate the cache, some other thread may suspend the operation
before reaching the for(;;) loop. Therefore the loop must start with
checking the chip->state before reading status from the chip.

Signed-off-by: Joakim Tjernlund <Joakim.Tjernlund@transmode.se>
Acked-by: Michael Cashwell <mboards@prograde.net>
Acked-by: Stefan Bigler <stefan.bigler@keymile.com>
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
Cc: stable@kernel.org

diff --git a/drivers/mtd/chips/cfi_cmdset_0001.c b/drivers/mtd/chips/cfi_cmdset_0001.c
index a8c3e1c9b02a78a64a79f5701abac9d1ba29a3e4..4aaa88f8ab5f0323f015dd34c46c4d0f98703ada 100644 (file)
--- a/drivers/mtd/chips/cfi_cmdset_0001.c
+++ b/drivers/mtd/chips/cfi_cmdset_0001.c
@@ -1230,10 +1230,32 @@ static int inval_cache_and_wait_for_operation(
        sleep_time = chip_op_time / 2;
 
        for (;;) {
+               if (chip->state != chip_state) {
+                       /* Someone's suspended the operation: sleep */
+                       DECLARE_WAITQUEUE(wait, current);
+                       set_current_state(TASK_UNINTERRUPTIBLE);
+                       add_wait_queue(&chip->wq, &wait);
+                       mutex_unlock(&chip->mutex);
+                       schedule();
+                       remove_wait_queue(&chip->wq, &wait);
+                       mutex_lock(&chip->mutex);
+                       continue;
+               }
+
                status = map_read(map, cmd_adr);
                if (map_word_andequal(map, status, status_OK, status_OK))
                        break;
 
+               if (chip->erase_suspended && chip_state == FL_ERASING)  {
+                       /* Erase suspend occured while sleep: reset timeout */
+                       timeo = reset_timeo;
+                       chip->erase_suspended = 0;
+               }
+               if (chip->write_suspended && chip_state == FL_WRITING)  {
+                       /* Write suspend occured while sleep: reset timeout */
+                       timeo = reset_timeo;
+                       chip->write_suspended = 0;
+               }
                if (!timeo) {
                        map_write(map, CMD(0x70), cmd_adr);
                        chip->state = FL_STATUS;
@@ -1257,27 +1279,6 @@ static int inval_cache_and_wait_for_operation(
                        timeo--;
                }
                mutex_lock(&chip->mutex);
-
-               while (chip->state != chip_state) {
-                       /* Someone's suspended the operation: sleep */
-                       DECLARE_WAITQUEUE(wait, current);
-                       set_current_state(TASK_UNINTERRUPTIBLE);
-                       add_wait_queue(&chip->wq, &wait);
-                       mutex_unlock(&chip->mutex);
-                       schedule();
-                       remove_wait_queue(&chip->wq, &wait);
-                       mutex_lock(&chip->mutex);
-               }
-               if (chip->erase_suspended && chip_state == FL_ERASING)  {
-                       /* Erase suspend occured while sleep: reset timeout */
-                       timeo = reset_timeo;
-                       chip->erase_suspended = 0;
-               }
-               if (chip->write_suspended && chip_state == FL_WRITING)  {
-                       /* Write suspend occured while sleep: reset timeout */
-                       timeo = reset_timeo;
-                       chip->write_suspended = 0;
-               }
        }
 
        /* Done and happy. */