[MTD] [NOR] fix cfi_cmdset_0001 FL_SYNCING race (take 2)

The patch fixes CFI issue with multipartitional devices leading to the 
set of errors or even deadlock. The problem is CFI FL_SYNCING state race 
with flash operations (e.g. erase suspend). It is reproduced by running 
intensive writes on one JFFS2 partition and simultaneously performing 
mount/unmount cycle on another partition of the same chip.

Signed-off-by: Alexander Belyakov <abelyako@googlemail.com>
Acked-by: Nicolas Pitre <nico@cam.org>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

1 files changed, 15 insertions, 2 deletions

diff --git a/drivers/mtd/chips/cfi_cmdset_0001.c b/drivers/mtd/chips/cfi_cmdset_0001.c
index 5157e3cb4b9e..c93a8be5d5f1 100644
--- a/drivers/mtd/chips/cfi_cmdset_0001.c
+++ b/drivers/mtd/chips/cfi_cmdset_0001.c
@@ -725,6 +725,10 @@ static int chip_ready (struct map_info *map, struct flchip *chip, unsigned long
         struct cfi_pri_intelext *cfip = cfi->cmdset_priv;
         unsigned long timeo = jiffies + HZ;
 
+        /* Prevent setting state FL_SYNCING for chip in suspended state. */
+        if (mode == FL_SYNCING && chip->oldstate != FL_READY)
+                goto sleep;
+
         switch (chip->state) {
 
         case FL_STATUS:
@@ -830,8 +834,9 @@ static int get_chip(struct map_info *map, struct flchip *chip, unsigned long adr
         DECLARE_WAITQUEUE(wait, current);
 
  retry:
-        if (chip->priv && (mode == FL_WRITING || mode == FL_ERASING
-                           || mode == FL_OTP_WRITE || mode == FL_SHUTDOWN)) {
+        if (chip->priv &&
+            (mode == FL_WRITING || mode == FL_ERASING || mode == FL_OTP_WRITE
+            || mode == FL_SHUTDOWN) && chip->state != FL_SYNCING) {
                 /*
                  * OK. We have possibility for contention on the write/erase
                  * operations which are global to the real chip and not per
@@ -881,6 +886,14 @@ static int get_chip(struct map_info *map, struct flchip *chip, unsigned long adr
                                 return ret;
                         }
                         spin_lock(&shared->lock);
+
+                        /* We should not own chip if it is already
+                         * in FL_SYNCING state. Put contender and retry. */
+                        if (chip->state == FL_SYNCING) {
+                                put_chip(map, contender, contender->start);
+                                spin_unlock(contender->mutex);
+                                goto retry;
+                        }
                         spin_unlock(contender->mutex);
                 }